diff --git a/case/plume/plume_cylinder_sweep/config.ini b/case/plume/plume_cylinder_sweep/config.ini
new file mode 100644
index 0000000..49b20bc
--- /dev/null
+++ b/case/plume/plume_cylinder_sweep/config.ini
@@ -0,0 +1,76 @@
+# Cylinder-target SWEEP smoke case: the plate-sweep setup re-aimed at a
+# CYLINDER target (data/stl/cylinder_transformed.stl -- radius 2 m, axis along
+# X in [-7, 0], centroid (-3.5, 0, 0)). The VV (single argon thruster, D = 1 m,
+# S0 = 2.0, Simplified kinetics + Maxwellian wall) is swept over 19 approach
+# angles x 5 orbit radii (95 firings; jfh_cylinder_sweep.A) about the cylinder
+# centroid, writing per-firing strikes to results/strikes/firing-<i>.vtu. This
+# case exists to confirm the strike pipeline RUNS on a curved/closed target;
+# the strike results are not physically meaningful. Geometry: the target is
+# the shared high-res mesh data/stl/cylinder.stl (14036 faces; resolved from
+# the shared data/ dir, not copied into the case per the repo's de-dup
+# convention); the sweep JFH is generated by
+# jfh/generate_cylinder_sweep_jfh.py (its centroid/radii are unchanged --
+# cylinder.stl and cylinder_transformed.stl share the same geometry).
+
+# Visiting Vehicle for RPOD analysis
+[vv]
+stl_lm = cylinder.stl
+stl_thruster = mold_funnel_transformed.stl
+
+# Target Vehicle for RPOD analysis
+[tv]
+stl = cylinder.stl
+
+# surface wall temperature (Kelvin): Tw/T0 = 1.5 (paper Figs. 17-21)
+surface_temp = 300
+
+# proportion of diffuse particle reflections [0, 1]
+sigma = 1
+
+# check plume constraints? 0 or 1
+check_constraints = 0
+
+# max heat flux integral (J/m^2)
+heat_flux_load = inf
+heat_flux_window_size = 1
+
+# max heat flux rate (W/m^2)
+heat_flux = inf
+
+# max pressure load
+normal_pressure_load = inf
+normal_pressure_window_size = inf
+
+# max normal pressure (N/m^2)
+normal_pressure = inf
+
+# max shear pressure (N/m^2)
+shear_pressure = inf
+
+# Plume kinetics and interactions models
+[pm]
+# Gas kinetics model
+kinetics = Simplified
+
+# Gas-surface interaction model
+surface_interaction = Maxwellian
+
+# Jet Firing History
+[jfh]
+jfh = jfh_cylinder_sweep.A
+
+# Thruster configuration data.
+[tcd]
+# Thruster Configuration File - single head-on thruster, no cant.
+tcf = tcf_1_argon.txt
+
+# Thruster Definition File - argon at the paper conditions.
+tdf = tdf.csv
+
+# Parameters for scaling plume geometry.
+[plume]
+radius = 25
+# ~89 deg: the default 0.436 (25 deg) would clip the plate -- its lower
+# corners sit ~70 deg off-axis at the paper distance. 1.55 rad keeps the
+# gating wedge clear of the whole plate at every sweep pose.
+wedge_theta = 1.55
diff --git a/case/plume/plume_cylinder_sweep/jfh/generate_cylinder_sweep_jfh.py b/case/plume/plume_cylinder_sweep/jfh/generate_cylinder_sweep_jfh.py
new file mode 100644
index 0000000..28bef6f
--- /dev/null
+++ b/case/plume/plume_cylinder_sweep/jfh/generate_cylinder_sweep_jfh.py
@@ -0,0 +1,75 @@
+"""Generate the sweep JFH for the cylinder-target smoke case.
+
+Same angle x distance sweep idea as the plate cases, but aimed at a CYLINDER
+target (data/stl/cylinder_transformed.stl: radius 2 m, axis along X spanning
+x in [-7, 0], centroid C = (-3.5, 0, 0), bounding-sphere radius ~4.03 m).
+
+The plate is replaced by the cylinder; the visiting vehicle (single thruster
+at the VV origin, no cant) is still swept. For each firing the VV is placed on
+the arc of radius L about the cylinder centroid C, with the thruster axis aimed
+at C and the JFH DCM set so the pipeline's plume normal (first column of the
+DCM, with the identity TCF) points along that axis:
+
+    d_hat(alpha) = cos(alpha) * n_hat + sin(alpha) * t_hat
+    VV position  = C + L * d_hat(alpha),  thruster axis = -d_hat(alpha)
+
+with n_hat = (0, 0, 1) and t_hat = (1, 0, 0), so the sweep orbits the cylinder
+in the global X-Z plane (alpha = 0 fires straight down -Z onto the curved
+surface; alpha = +/-90 fires along -/+X at the end caps).
+
+The orbit radii all exceed the cylinder's bounding sphere so the VV never sits
+inside the target (this case is a pipeline smoke test -- the strike results are
+not physically meaningful). Sweep: alpha from -90 to +90 deg in 10 deg steps
+(19 angles) x L in {6, 8, 10, 12, 14} m, enumerated distance-major:
+firing index = i_L * 19 + i_alpha + 1. 95 firings total, 1.0 s each.
+
+JFH files are always generated by script, never hand-edited. Run from this
+directory:  python generate_cylinder_sweep_jfh.py
+"""
+
+from pathlib import Path
+
+import numpy as np
+
+from generate_jfh_inclined_plate import write_jfh
+
+OUT_NAME = 'jfh_cylinder_sweep.A'
+
+CYLINDER_CENTER = np.array([-3.5, 0.0, 0.0])
+ALPHA0_DEG = 0.0                       # global-frame orbit-plane tilt
+ALPHAS_DEG = np.arange(-90.0, 90.0 + 1e-9, 10.0)
+RADII = [6.0, 8.0, 10.0, 12.0, 14.0]   # arc radii (m); all > ~4.03 bounding sphere
+
+
+def pose_for(alpha_deg, L):
+    """(vv_position, dcm) for one sweep firing; dcm's first column is the
+    thruster axis (see the pipeline's plume-normal convention)."""
+    a0 = np.deg2rad(ALPHA0_DEG)
+    n_hat = np.array([-np.sin(a0), 0.0, np.cos(a0)])
+    t_hat = np.array([np.cos(a0), 0.0, np.sin(a0)])
+    alpha = np.deg2rad(alpha_deg)
+    d_hat = np.cos(alpha) * n_hat + np.sin(alpha) * t_hat
+    position = CYLINDER_CENTER + L * d_hat
+    axis = -d_hat                       # aimed at the cylinder centroid
+    # right-handed triad; the axis always lies in the X-Z plane, so the
+    # global Y axis is a valid second column
+    c1 = np.array([0.0, 1.0, 0.0])
+    c2 = np.cross(axis, c1)
+    dcm = np.column_stack([axis, c1, c2])
+    return position, dcm
+
+
+def dcm_string(dcm):
+    return ' '.join(f'{v:.6e}' for v in np.asarray(dcm).ravel())
+
+
+if __name__ == '__main__':
+    firings = []
+    for L in RADII:
+        for alpha_deg in ALPHAS_DEG:
+            position, dcm = pose_for(alpha_deg, L)
+            firings.append((0.0, 1.0, dcm_string(dcm), tuple(position), [1]))
+    out_path = Path(__file__).resolve().parent / OUT_NAME
+    write_jfh(out_path, firings)
+    print(f'saved {out_path} ({len(firings)} firings: '
+          f'{len(ALPHAS_DEG)} angles x {len(RADII)} radii)')
diff --git a/case/plume/plume_cylinder_sweep/jfh/generate_jfh_inclined_plate.py b/case/plume/plume_cylinder_sweep/jfh/generate_jfh_inclined_plate.py
new file mode 100644
index 0000000..249f71d
--- /dev/null
+++ b/case/plume/plume_cylinder_sweep/jfh/generate_jfh_inclined_plate.py
@@ -0,0 +1,37 @@
+"""Generate the single-firing JFH for the Cai 2016 inclined-plate case.
+
+One firing at the paper geometry (Aerospace 2016, 3(4):43, Section 4): the
+visiting vehicle sits at the origin with an identity DCM, so its single
+thruster (exit at the VV origin, no cant) fires along +X toward the plate
+centered at (4, 0, 0) m. Firing time 1.0 s makes heat_flux_load equal the
+heat-flux rate.
+
+JFH files are always generated by script, never hand-edited. Run from this
+directory:  python generate_jfh_inclined_plate.py
+"""
+
+from pathlib import Path
+
+OUT_NAME = 'jfh_plume_inclined_plate.A'
+
+DCM_IDENTITY = ('1.000000e+00 0.000000e+00 0.000000e+00 '
+                '0.000000e+00 1.000000e+00 0.000000e+00 '
+                '0.000000e+00 0.000000e+00 1.000000e+00')
+
+
+def write_jfh(path, firings):
+    """firings: list of (dt, t, dcm_str, xyz, thrusters)."""
+    lines = [f'offseted    {len(firings)}       0', '       0.000       0.000       0.000']
+    for n, (dt, t, dcm, xyz, thrusters) in enumerate(firings, start=1):
+        xyz_str = ' '.join(f'{v:.9g}' for v in xyz)
+        thr_str = ' '.join(str(i) for i in thrusters)
+        lines.append(f'      {n} {dt:g} {t:g} 0 {dcm} {xyz_str} 1 '
+                     f'{len(thrusters)} {thr_str}')
+    with open(path, 'w', newline='\n') as fh:
+        fh.write('\n'.join(lines) + '\n')
+
+
+if __name__ == '__main__':
+    out_path = Path(__file__).resolve().parent / OUT_NAME
+    write_jfh(out_path, [(0.0, 1.0, DCM_IDENTITY, (0.0, 0.0, 0.0), [1])])
+    print(f'saved {out_path}')
diff --git a/case/plume/plume_cylinder_sweep/jfh/jfh_cylinder_sweep.A b/case/plume/plume_cylinder_sweep/jfh/jfh_cylinder_sweep.A
new file mode 100644
index 0000000..f60a586
--- /dev/null
+++ b/case/plume/plume_cylinder_sweep/jfh/jfh_cylinder_sweep.A
@@ -0,0 +1,97 @@
+offseted    95       0
+       0.000       0.000       0.000
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+      55 0 1 0 -9.396926e-01 0.000000e+00 3.420201e-01 -0.000000e+00 1.000000e+00 0.000000e+00 -3.420201e-01 0.000000e+00 -9.396926e-01 5.89692621 0 3.42020143 1 1 1
+      56 0 1 0 -9.848078e-01 0.000000e+00 1.736482e-01 -0.000000e+00 1.000000e+00 0.000000e+00 -1.736482e-01 0.000000e+00 -9.848078e-01 6.34807753 0 1.73648178 1 1 1
+      57 0 1 0 -1.000000e+00 0.000000e+00 6.123234e-17 -0.000000e+00 1.000000e+00 0.000000e+00 -6.123234e-17 0.000000e+00 -1.000000e+00 6.5 0 6.123234e-16 1 1 1
+      58 0 1 0 1.000000e+00 0.000000e+00 6.123234e-17 -0.000000e+00 1.000000e+00 -0.000000e+00 -6.123234e-17 0.000000e+00 1.000000e+00 -15.5 0 7.34788079e-16 1 1 1
+      59 0 1 0 9.848078e-01 0.000000e+00 1.736482e-01 -0.000000e+00 1.000000e+00 -0.000000e+00 -1.736482e-01 0.000000e+00 9.848078e-01 -15.317693 0 2.08377813 1 1 1
+      60 0 1 0 9.396926e-01 0.000000e+00 3.420201e-01 -0.000000e+00 1.000000e+00 -0.000000e+00 -3.420201e-01 0.000000e+00 9.396926e-01 -14.7763114 0 4.10424172 1 1 1
+      61 0 1 0 8.660254e-01 0.000000e+00 5.000000e-01 -0.000000e+00 1.000000e+00 -0.000000e+00 -5.000000e-01 0.000000e+00 8.660254e-01 -13.8923048 0 6 1 1 1
+      62 0 1 0 7.660444e-01 0.000000e+00 6.427876e-01 -0.000000e+00 1.000000e+00 -0.000000e+00 -6.427876e-01 0.000000e+00 7.660444e-01 -12.6925333 0 7.71345132 1 1 1
+      63 0 1 0 6.427876e-01 0.000000e+00 7.660444e-01 -0.000000e+00 1.000000e+00 -0.000000e+00 -7.660444e-01 0.000000e+00 6.427876e-01 -11.2134513 0 9.19253332 1 1 1
+      64 0 1 0 5.000000e-01 0.000000e+00 8.660254e-01 -0.000000e+00 1.000000e+00 -0.000000e+00 -8.660254e-01 0.000000e+00 5.000000e-01 -9.5 0 10.3923048 1 1 1
+      65 0 1 0 3.420201e-01 0.000000e+00 9.396926e-01 -0.000000e+00 1.000000e+00 -0.000000e+00 -9.396926e-01 0.000000e+00 3.420201e-01 -7.60424172 0 11.2763114 1 1 1
+      66 0 1 0 1.736482e-01 0.000000e+00 9.848078e-01 -0.000000e+00 1.000000e+00 -0.000000e+00 -9.848078e-01 0.000000e+00 1.736482e-01 -5.58377813 0 11.817693 1 1 1
+      67 0 1 0 -0.000000e+00 0.000000e+00 1.000000e+00 -0.000000e+00 1.000000e+00 0.000000e+00 -1.000000e+00 0.000000e+00 0.000000e+00 -3.5 0 12 1 1 1
+      68 0 1 0 -1.736482e-01 0.000000e+00 9.848078e-01 -0.000000e+00 1.000000e+00 0.000000e+00 -9.848078e-01 0.000000e+00 -1.736482e-01 -1.41622187 0 11.817693 1 1 1
+      69 0 1 0 -3.420201e-01 0.000000e+00 9.396926e-01 -0.000000e+00 1.000000e+00 0.000000e+00 -9.396926e-01 0.000000e+00 -3.420201e-01 0.60424172 0 11.2763114 1 1 1
+      70 0 1 0 -5.000000e-01 0.000000e+00 8.660254e-01 -0.000000e+00 1.000000e+00 0.000000e+00 -8.660254e-01 0.000000e+00 -5.000000e-01 2.5 0 10.3923048 1 1 1
+      71 0 1 0 -6.427876e-01 0.000000e+00 7.660444e-01 -0.000000e+00 1.000000e+00 0.000000e+00 -7.660444e-01 0.000000e+00 -6.427876e-01 4.21345132 0 9.19253332 1 1 1
+      72 0 1 0 -7.660444e-01 0.000000e+00 6.427876e-01 -0.000000e+00 1.000000e+00 0.000000e+00 -6.427876e-01 0.000000e+00 -7.660444e-01 5.69253332 0 7.71345132 1 1 1
+      73 0 1 0 -8.660254e-01 0.000000e+00 5.000000e-01 -0.000000e+00 1.000000e+00 0.000000e+00 -5.000000e-01 0.000000e+00 -8.660254e-01 6.89230485 0 6 1 1 1
+      74 0 1 0 -9.396926e-01 0.000000e+00 3.420201e-01 -0.000000e+00 1.000000e+00 0.000000e+00 -3.420201e-01 0.000000e+00 -9.396926e-01 7.77631145 0 4.10424172 1 1 1
+      75 0 1 0 -9.848078e-01 0.000000e+00 1.736482e-01 -0.000000e+00 1.000000e+00 0.000000e+00 -1.736482e-01 0.000000e+00 -9.848078e-01 8.31769304 0 2.08377813 1 1 1
+      76 0 1 0 -1.000000e+00 0.000000e+00 6.123234e-17 -0.000000e+00 1.000000e+00 0.000000e+00 -6.123234e-17 0.000000e+00 -1.000000e+00 8.5 0 7.34788079e-16 1 1 1
+      77 0 1 0 1.000000e+00 0.000000e+00 6.123234e-17 -0.000000e+00 1.000000e+00 -0.000000e+00 -6.123234e-17 0.000000e+00 1.000000e+00 -17.5 0 8.57252759e-16 1 1 1
+      78 0 1 0 9.848078e-01 0.000000e+00 1.736482e-01 -0.000000e+00 1.000000e+00 -0.000000e+00 -1.736482e-01 0.000000e+00 9.848078e-01 -17.2873085 0 2.43107449 1 1 1
+      79 0 1 0 9.396926e-01 0.000000e+00 3.420201e-01 -0.000000e+00 1.000000e+00 -0.000000e+00 -3.420201e-01 0.000000e+00 9.396926e-01 -16.6556967 0 4.78828201 1 1 1
+      80 0 1 0 8.660254e-01 0.000000e+00 5.000000e-01 -0.000000e+00 1.000000e+00 -0.000000e+00 -5.000000e-01 0.000000e+00 8.660254e-01 -15.6243557 0 7 1 1 1
+      81 0 1 0 7.660444e-01 0.000000e+00 6.427876e-01 -0.000000e+00 1.000000e+00 -0.000000e+00 -6.427876e-01 0.000000e+00 7.660444e-01 -14.2246222 0 8.99902654 1 1 1
+      82 0 1 0 6.427876e-01 0.000000e+00 7.660444e-01 -0.000000e+00 1.000000e+00 -0.000000e+00 -7.660444e-01 0.000000e+00 6.427876e-01 -12.4990265 0 10.7246222 1 1 1
+      83 0 1 0 5.000000e-01 0.000000e+00 8.660254e-01 -0.000000e+00 1.000000e+00 -0.000000e+00 -8.660254e-01 0.000000e+00 5.000000e-01 -10.5 0 12.1243557 1 1 1
+      84 0 1 0 3.420201e-01 0.000000e+00 9.396926e-01 -0.000000e+00 1.000000e+00 -0.000000e+00 -9.396926e-01 0.000000e+00 3.420201e-01 -8.28828201 0 13.1556967 1 1 1
+      85 0 1 0 1.736482e-01 0.000000e+00 9.848078e-01 -0.000000e+00 1.000000e+00 -0.000000e+00 -9.848078e-01 0.000000e+00 1.736482e-01 -5.93107449 0 13.7873085 1 1 1
+      86 0 1 0 -0.000000e+00 0.000000e+00 1.000000e+00 -0.000000e+00 1.000000e+00 0.000000e+00 -1.000000e+00 0.000000e+00 0.000000e+00 -3.5 0 14 1 1 1
+      87 0 1 0 -1.736482e-01 0.000000e+00 9.848078e-01 -0.000000e+00 1.000000e+00 0.000000e+00 -9.848078e-01 0.000000e+00 -1.736482e-01 -1.06892551 0 13.7873085 1 1 1
+      88 0 1 0 -3.420201e-01 0.000000e+00 9.396926e-01 -0.000000e+00 1.000000e+00 0.000000e+00 -9.396926e-01 0.000000e+00 -3.420201e-01 1.28828201 0 13.1556967 1 1 1
+      89 0 1 0 -5.000000e-01 0.000000e+00 8.660254e-01 -0.000000e+00 1.000000e+00 0.000000e+00 -8.660254e-01 0.000000e+00 -5.000000e-01 3.5 0 12.1243557 1 1 1
+      90 0 1 0 -6.427876e-01 0.000000e+00 7.660444e-01 -0.000000e+00 1.000000e+00 0.000000e+00 -7.660444e-01 0.000000e+00 -6.427876e-01 5.49902654 0 10.7246222 1 1 1
+      91 0 1 0 -7.660444e-01 0.000000e+00 6.427876e-01 -0.000000e+00 1.000000e+00 0.000000e+00 -6.427876e-01 0.000000e+00 -7.660444e-01 7.2246222 0 8.99902654 1 1 1
+      92 0 1 0 -8.660254e-01 0.000000e+00 5.000000e-01 -0.000000e+00 1.000000e+00 0.000000e+00 -5.000000e-01 0.000000e+00 -8.660254e-01 8.62435565 0 7 1 1 1
+      93 0 1 0 -9.396926e-01 0.000000e+00 3.420201e-01 -0.000000e+00 1.000000e+00 0.000000e+00 -3.420201e-01 0.000000e+00 -9.396926e-01 9.65569669 0 4.78828201 1 1 1
+      94 0 1 0 -9.848078e-01 0.000000e+00 1.736482e-01 -0.000000e+00 1.000000e+00 0.000000e+00 -1.736482e-01 0.000000e+00 -9.848078e-01 10.2873085 0 2.43107449 1 1 1
+      95 0 1 0 -1.000000e+00 0.000000e+00 6.123234e-17 -0.000000e+00 1.000000e+00 0.000000e+00 -6.123234e-17 0.000000e+00 -1.000000e+00 10.5 0 8.57252759e-16 1 1 1
diff --git a/case/plume/plume_cylinder_sweep/tcd/tcf_1_argon.txt b/case/plume/plume_cylinder_sweep/tcd/tcf_1_argon.txt
new file mode 100644
index 0000000..53e6e0e
--- /dev/null
+++ b/case/plume/plume_cylinder_sweep/tcd/tcf_1_argon.txt
@@ -0,0 +1,6 @@
+1
+m
+0.000000 0.000000 0.000000
+0.000000 0.000000 0.000000
+T1 ARG 0 0 0 1.000000e+00 0.000000e+00 0.000000e+00 0.000000e+00 1.000000e+00 0.000000e+00 0.000000e+00 0.000000e+00 1.000000e+00
+0
diff --git a/case/plume/plume_cylinder_sweep/tcd/tdf.csv b/case/plume/plume_cylinder_sweep/tcd/tdf.csv
new file mode 100644
index 0000000..dc39035
--- /dev/null
+++ b/case/plume/plume_cylinder_sweep/tcd/tdf.csv
@@ -0,0 +1,2 @@
+#,name,prop,F,isp,MIB,m,mdot,ve,d,R,gamma,Te,rhoe,n
+ARG,CAI2016,argon,1,1,1,1,0.001,577.0684534784414,1.0,208.13,1.6666666666666667,200,6.6329E-06,1.0E+20
diff --git a/case/plume/plume_flat_plate_sweep/config.ini b/case/plume/plume_flat_plate_sweep/config.ini
new file mode 100644
index 0000000..60238f8
--- /dev/null
+++ b/case/plume/plume_flat_plate_sweep/config.ini
@@ -0,0 +1,73 @@
+# Cai 2016 FLAT-plate SWEEP case (Aerospace 3(4):43, Section 4): a pure
+# global-frame reframing of the paper geometry to alpha0 = 0 (flat 8 m x 8 m
+# plate in the X-Y plane, center at the origin, argon round jet D = 1 m,
+# S0 = 2.0, T0 = 200 K, Tw = 300 K, fully diffuse), swept over 19 approach
+# angles x 5 stand-off distances (95 firings; jfh_flat_plate_sweep.A). The
+# reframing is physics-invariant, so this reproduces the same coefficients as
+# the sibling plume_inclined_plate_sweep but with strikes that read cleanly in
+# ParaView (results/strikes/firing-<i>.vtu). Driven by
+# tests/rpod/rpod_verification_test_06.py. Geometry assets are generated by
+# the scripts in stl/ and jfh/ (--alpha0-deg 0 --distance 0; see docstrings).
+
+# Visiting Vehicle for RPOD analysis
+[vv]
+stl_lm = cylinder_transformed.stl
+stl_thruster = mold_funnel_transformed.stl
+
+# Target Vehicle for RPOD analysis
+[tv]
+stl = flat_plate_transformed.stl
+
+# surface wall temperature (Kelvin): Tw/T0 = 1.5 (paper Figs. 17-21)
+surface_temp = 300
+
+# proportion of diffuse particle reflections [0, 1]
+sigma = 1
+
+# check plume constraints? 0 or 1
+check_constraints = 0
+
+# max heat flux integral (J/m^2)
+heat_flux_load = inf
+heat_flux_window_size = 1
+
+# max heat flux rate (W/m^2)
+heat_flux = inf
+
+# max pressure load
+normal_pressure_load = inf
+normal_pressure_window_size = inf
+
+# max normal pressure (N/m^2)
+normal_pressure = inf
+
+# max shear pressure (N/m^2)
+shear_pressure = inf
+
+# Plume kinetics and interactions models
+[pm]
+# Gas kinetics model
+kinetics = Simplified
+
+# Gas-surface interaction model
+surface_interaction = Maxwellian
+
+# Jet Firing History
+[jfh]
+jfh = jfh_flat_plate_sweep.A
+
+# Thruster configuration data.
+[tcd]
+# Thruster Configuration File - single head-on thruster, no cant.
+tcf = tcf_1_argon.txt
+
+# Thruster Definition File - argon at the paper conditions.
+tdf = tdf.csv
+
+# Parameters for scaling plume geometry.
+[plume]
+radius = 25
+# ~89 deg: the default 0.436 (25 deg) would clip the plate -- its lower
+# corners sit ~70 deg off-axis at the paper distance. 1.55 rad keeps the
+# gating wedge clear of the whole plate at every sweep pose.
+wedge_theta = 1.55
diff --git a/case/plume/plume_flat_plate_sweep/jfh/generate_jfh_inclined_plate.py b/case/plume/plume_flat_plate_sweep/jfh/generate_jfh_inclined_plate.py
new file mode 100644
index 0000000..249f71d
--- /dev/null
+++ b/case/plume/plume_flat_plate_sweep/jfh/generate_jfh_inclined_plate.py
@@ -0,0 +1,37 @@
+"""Generate the single-firing JFH for the Cai 2016 inclined-plate case.
+
+One firing at the paper geometry (Aerospace 2016, 3(4):43, Section 4): the
+visiting vehicle sits at the origin with an identity DCM, so its single
+thruster (exit at the VV origin, no cant) fires along +X toward the plate
+centered at (4, 0, 0) m. Firing time 1.0 s makes heat_flux_load equal the
+heat-flux rate.
+
+JFH files are always generated by script, never hand-edited. Run from this
+directory:  python generate_jfh_inclined_plate.py
+"""
+
+from pathlib import Path
+
+OUT_NAME = 'jfh_plume_inclined_plate.A'
+
+DCM_IDENTITY = ('1.000000e+00 0.000000e+00 0.000000e+00 '
+                '0.000000e+00 1.000000e+00 0.000000e+00 '
+                '0.000000e+00 0.000000e+00 1.000000e+00')
+
+
+def write_jfh(path, firings):
+    """firings: list of (dt, t, dcm_str, xyz, thrusters)."""
+    lines = [f'offseted    {len(firings)}       0', '       0.000       0.000       0.000']
+    for n, (dt, t, dcm, xyz, thrusters) in enumerate(firings, start=1):
+        xyz_str = ' '.join(f'{v:.9g}' for v in xyz)
+        thr_str = ' '.join(str(i) for i in thrusters)
+        lines.append(f'      {n} {dt:g} {t:g} 0 {dcm} {xyz_str} 1 '
+                     f'{len(thrusters)} {thr_str}')
+    with open(path, 'w', newline='\n') as fh:
+        fh.write('\n'.join(lines) + '\n')
+
+
+if __name__ == '__main__':
+    out_path = Path(__file__).resolve().parent / OUT_NAME
+    write_jfh(out_path, [(0.0, 1.0, DCM_IDENTITY, (0.0, 0.0, 0.0), [1])])
+    print(f'saved {out_path}')
diff --git a/case/plume/plume_flat_plate_sweep/jfh/generate_sweep_jfh.py b/case/plume/plume_flat_plate_sweep/jfh/generate_sweep_jfh.py
new file mode 100644
index 0000000..a8e574f
--- /dev/null
+++ b/case/plume/plume_flat_plate_sweep/jfh/generate_sweep_jfh.py
@@ -0,0 +1,101 @@
+"""Generate the ONE sweep JFH for the Phase-3 angle x distance study.
+
+The plate is STATIONARY (target vehicles do not move): the visiting vehicle
+is swept instead. For each firing the VV (single thruster at the VV origin,
+no cant) is placed on the arc of radius L about the plate center
+C = (4, 0, 0), with the thruster axis aimed at C and the JFH DCM set so the
+pipeline's plume normal (first column of the DCM, with the identity TCF)
+points along that axis.
+
+Pose parametrization, all in the plate's tilt plane (global X-Z):
+
+    d_hat(alpha) = cos(alpha) * n_hat + sin(alpha) * t_hat
+    VV position  = C + L * d_hat(alpha),  thruster axis = -d_hat(alpha)
+
+where n_hat = (-sin 60, 0, cos 60) is the plate normal facing the nozzle
+side and t_hat = (cos 60, 0, sin 60) the plate's inclined tangent.
+alpha = 0 is HEAD-ON (thruster axis along the plate normal; the paper's
+alpha0 = 90 deg); the sign is the tilt direction, mapping
+alpha_paper = 90 deg - |alpha|. Results must be mirror-symmetric in
++/-alpha (the plate is square); +/-90 deg is edge-on/degenerate and is
+kept to confirm ~zero struck faces.
+
+Sweep: alpha from -90 to +90 deg in 10 deg steps (19 angles) x
+L/D in {2, 4, 6, 8, 10} (D = 1 m), enumerated distance-major:
+firing index = i_L * 19 + i_alpha + 1. 95 firings total, firing time
+1.0 s each.
+
+JFH files are always generated by script, never hand-edited. Run from this
+directory:  python generate_sweep_jfh.py
+"""
+
+from pathlib import Path
+
+import numpy as np
+
+from generate_jfh_inclined_plate import write_jfh
+
+OUT_NAME = 'jfh_inclined_plate_sweep.A'
+
+PLATE_CENTER = np.array([4.0, 0.0, 0.0])
+ALPHA0_DEG = 60.0
+ALPHAS_DEG = np.arange(-90.0, 90.0 + 1e-9, 10.0)
+L_OVER_D = [2.0, 4.0, 6.0, 8.0, 10.0]
+
+
+def pose_for(alpha_deg, L, plate_center=PLATE_CENTER, alpha0_deg=ALPHA0_DEG):
+    """(vv_position, dcm) for one sweep firing; dcm's first column is the
+    thruster axis (see the pipeline's plume-normal convention).
+
+    plate_center / alpha0_deg place the whole {plate + swept-arc} rig in the
+    global frame. They are physics-invariant (every relative incidence, and
+    thus every coefficient, is preserved under this rigid rotation +
+    translation) -- a flat alpha0 = 0 variant is a pure visualization
+    reframing of the same case. They must match the target STL's own
+    center/tilt (stl/transform_inclined_plate.py) and the analysis constants
+    (tests/rpod/rpod_verification_test_06.py)."""
+    a0 = np.deg2rad(alpha0_deg)
+    n_hat = np.array([-np.sin(a0), 0.0, np.cos(a0)])
+    t_hat = np.array([np.cos(a0), 0.0, np.sin(a0)])
+    alpha = np.deg2rad(alpha_deg)
+    d_hat = np.cos(alpha) * n_hat + np.sin(alpha) * t_hat
+    position = np.asarray(plate_center, dtype=float) + L * d_hat
+    axis = -d_hat                       # aimed at the plate center
+    # right-handed triad; the axis always lies in the X-Z plane, so the
+    # global Y axis is a valid second column
+    c1 = np.array([0.0, 1.0, 0.0])
+    c2 = np.cross(axis, c1)
+    dcm = np.column_stack([axis, c1, c2])
+    return position, dcm
+
+
+def dcm_string(dcm):
+    return ' '.join(f'{v:.6e}' for v in np.asarray(dcm).ravel())
+
+
+if __name__ == '__main__':
+    import argparse
+
+    parser = argparse.ArgumentParser(description=__doc__.splitlines()[0])
+    parser.add_argument('--alpha0-deg', type=float, default=ALPHA0_DEG,
+                        help='global-frame plate tilt (deg); physics-'
+                             'invariant, must match the target STL')
+    parser.add_argument('--distance', type=float, default=PLATE_CENTER[0],
+                        help='plate-center X in the global frame (m); the '
+                             'center is (distance, 0, 0)')
+    parser.add_argument('--out', type=str, default=OUT_NAME,
+                        help='output JFH filename in this jfh/ folder')
+    args = parser.parse_args()
+
+    plate_center = np.array([args.distance, 0.0, 0.0])
+    firings = []
+    for L in L_OVER_D:
+        for alpha_deg in ALPHAS_DEG:
+            position, dcm = pose_for(alpha_deg, L, plate_center=plate_center,
+                                     alpha0_deg=args.alpha0_deg)
+            firings.append((0.0, 1.0, dcm_string(dcm), tuple(position), [1]))
+    out_path = Path(__file__).resolve().parent / args.out
+    write_jfh(out_path, firings)
+    print(f'saved {out_path} ({len(firings)} firings: '
+          f'{len(ALPHAS_DEG)} angles x {len(L_OVER_D)} distances, '
+          f'alpha0 = {args.alpha0_deg} deg, center X = {args.distance} m)')
diff --git a/case/plume/plume_flat_plate_sweep/jfh/jfh_flat_plate_sweep.A b/case/plume/plume_flat_plate_sweep/jfh/jfh_flat_plate_sweep.A
new file mode 100644
index 0000000..b32d99d
--- /dev/null
+++ b/case/plume/plume_flat_plate_sweep/jfh/jfh_flat_plate_sweep.A
@@ -0,0 +1,97 @@
+offseted    95       0
+       0.000       0.000       0.000
+      1 0 1 0 1.000000e+00 0.000000e+00 6.123234e-17 -0.000000e+00 1.000000e+00 -0.000000e+00 -6.123234e-17 0.000000e+00 1.000000e+00 -2 0 1.2246468e-16 1 1 1
+      2 0 1 0 9.848078e-01 0.000000e+00 1.736482e-01 -0.000000e+00 1.000000e+00 -0.000000e+00 -1.736482e-01 0.000000e+00 9.848078e-01 -1.96961551 0 0.347296355 1 1 1
+      3 0 1 0 9.396926e-01 0.000000e+00 3.420201e-01 -0.000000e+00 1.000000e+00 -0.000000e+00 -3.420201e-01 0.000000e+00 9.396926e-01 -1.87938524 0 0.684040287 1 1 1
+      4 0 1 0 8.660254e-01 0.000000e+00 5.000000e-01 -0.000000e+00 1.000000e+00 -0.000000e+00 -5.000000e-01 0.000000e+00 8.660254e-01 -1.73205081 0 1 1 1 1
+      5 0 1 0 7.660444e-01 0.000000e+00 6.427876e-01 -0.000000e+00 1.000000e+00 -0.000000e+00 -6.427876e-01 0.000000e+00 7.660444e-01 -1.53208889 0 1.28557522 1 1 1
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diff --git a/case/plume/plume_flat_plate_sweep/stl/flat_plate_transformed.stl b/case/plume/plume_flat_plate_sweep/stl/flat_plate_transformed.stl
new file mode 100644
index 0000000..fe62d0f
Binary files /dev/null and b/case/plume/plume_flat_plate_sweep/stl/flat_plate_transformed.stl differ
diff --git a/case/plume/plume_flat_plate_sweep/stl/transform_inclined_plate.py b/case/plume/plume_flat_plate_sweep/stl/transform_inclined_plate.py
new file mode 100644
index 0000000..dc6d9be
--- /dev/null
+++ b/case/plume/plume_flat_plate_sweep/stl/transform_inclined_plate.py
@@ -0,0 +1,101 @@
+"""Generate the inclined-plate target mesh for the Cai 2016 verification case.
+
+Builds a single-sided, uniformly triangulated rectangular plate matching the
+paper's Section-4 geometry (Aerospace 2016, 3(4):43): an 8 m x 8 m plate whose
+center sits at (L, 0, 0) = (4, 0, 0) m from the nozzle exit, inclined by
+alpha0 = 60 deg. The thruster fires along +X from a head-on JFH pose (VV at
+the origin, identity DCM), so the global frame coincides with the paper's
+nozzle frame and with pyrpod/plume/CaiImpingement2016.py:
+
+    plate point(s, tau) = center + s * (0, 1, 0) + tau * (cos a0, 0, sin a0)
+
+Every face normal points toward the thruster, (-sin a0, 0, cos a0), which the
+strike pipeline's facing test (surface_dot_plume < 0) requires; the script
+asserts this before saving.
+
+Angle, distance, plate size, and mesh resolution are parametrized for the
+Phase-3 sweep reuse. Defaults reproduce the paper case with 2 * 72^2 = 10368
+faces (~0.11 m elements): contour-quality resolution at a per-face kinetics
+cost that keeps a single firing in the tens of seconds.
+
+Run from this directory:  python transform_inclined_plate.py
+"""
+
+import argparse
+from pathlib import Path
+
+import numpy as np
+from stl import mesh
+
+
+def build_plate_mesh(alpha0_deg=60.0, center=(4.0, 0.0, 0.0),
+                     half_width=4.0, half_height=4.0, n_div=72):
+    """Return a numpy-stl Mesh of the inclined plate.
+
+    Parameters
+    ----------
+    alpha0_deg : float
+        plate inclination angle alpha0 (deg); 90 = normal to the jet axis
+    center : sequence of float
+        plate center in the global/nozzle frame (m)
+    half_width : float
+        semi-width W0 along the horizontal s direction (m)
+    half_height : float
+        semi-length H0 along the inclined tau direction (m)
+    n_div : int
+        quad divisions per axis (faces = 2 * n_div^2)
+    """
+    a0 = np.deg2rad(alpha0_deg)
+    center = np.asarray(center, dtype=float)
+    t_s = np.array([0.0, 1.0, 0.0])
+    t_tau = np.array([np.cos(a0), 0.0, np.sin(a0)])
+    normal = np.array([-np.sin(a0), 0.0, np.cos(a0)])
+
+    s_edges = np.linspace(-half_width, half_width, n_div + 1)
+    tau_edges = np.linspace(-half_height, half_height, n_div + 1)
+
+    def point(s, tau):
+        return center + s * t_s + tau * t_tau
+
+    data = np.zeros(2 * n_div * n_div, dtype=mesh.Mesh.dtype)
+    k = 0
+    for i in range(n_div):
+        for j in range(n_div):
+            p00 = point(s_edges[i], tau_edges[j])
+            p10 = point(s_edges[i + 1], tau_edges[j])
+            p01 = point(s_edges[i], tau_edges[j + 1])
+            p11 = point(s_edges[i + 1], tau_edges[j + 1])
+            # wound so cross(v1-v0, v2-v0) points along `normal`
+            data['vectors'][k] = np.array([p00, p01, p11])
+            data['vectors'][k + 1] = np.array([p00, p11, p10])
+            k += 2
+
+    plate = mesh.Mesh(data)
+    plate.update_normals()
+    unit_normals = plate.get_unit_normals()
+    assert np.allclose(unit_normals, normal, atol=1e-9), (
+        'face normals do not all point toward the thruster')
+    return plate
+
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser(description=__doc__.splitlines()[0])
+    parser.add_argument('--alpha0-deg', type=float, default=60.0)
+    parser.add_argument('--distance', type=float, default=4.0,
+                        help='nozzle-to-plate-center distance L (m)')
+    parser.add_argument('--half-width', type=float, default=4.0)
+    parser.add_argument('--half-height', type=float, default=4.0)
+    parser.add_argument('--n-div', type=int, default=72)
+    parser.add_argument('--out', type=str,
+                        default='inclined_plate_transformed.stl')
+    args = parser.parse_args()
+
+    plate = build_plate_mesh(alpha0_deg=args.alpha0_deg,
+                             center=(args.distance, 0.0, 0.0),
+                             half_width=args.half_width,
+                             half_height=args.half_height,
+                             n_div=args.n_div)
+    out_path = Path(__file__).resolve().parent / args.out
+    plate.save(str(out_path))
+    print(f'saved {out_path} ({len(plate.vectors)} faces, '
+          f'alpha0 = {args.alpha0_deg} deg, L = {args.distance} m)')
diff --git a/case/plume/plume_flat_plate_sweep/tcd/tcf_1_argon.txt b/case/plume/plume_flat_plate_sweep/tcd/tcf_1_argon.txt
new file mode 100644
index 0000000..53e6e0e
--- /dev/null
+++ b/case/plume/plume_flat_plate_sweep/tcd/tcf_1_argon.txt
@@ -0,0 +1,6 @@
+1
+m
+0.000000 0.000000 0.000000
+0.000000 0.000000 0.000000
+T1 ARG 0 0 0 1.000000e+00 0.000000e+00 0.000000e+00 0.000000e+00 1.000000e+00 0.000000e+00 0.000000e+00 0.000000e+00 1.000000e+00
+0
diff --git a/case/plume/plume_flat_plate_sweep/tcd/tdf.csv b/case/plume/plume_flat_plate_sweep/tcd/tdf.csv
new file mode 100644
index 0000000..dc39035
--- /dev/null
+++ b/case/plume/plume_flat_plate_sweep/tcd/tdf.csv
@@ -0,0 +1,2 @@
+#,name,prop,F,isp,MIB,m,mdot,ve,d,R,gamma,Te,rhoe,n
+ARG,CAI2016,argon,1,1,1,1,0.001,577.0684534784414,1.0,208.13,1.6666666666666667,200,6.6329E-06,1.0E+20
diff --git a/case/plume/plume_inclined_plate/config.ini b/case/plume/plume_inclined_plate/config.ini
new file mode 100644
index 0000000..e8192e1
--- /dev/null
+++ b/case/plume/plume_inclined_plate/config.ini
@@ -0,0 +1,68 @@
+# Cai 2016 inclined-plate impingement verification case (Aerospace 3(4):43,
+# Section 4): argon round jet, D = 1 m, S0 = 2.0 (ve = S0*sqrt(2*R*T0)),
+# T0 = 200 K, plate 8 m x 8 m at L = 4D inclined alpha0 = 60 deg, Tw = 300 K,
+# fully diffuse (sigma = 1). Geometry assets are generated by the scripts in
+# stl/ and jfh/ (see their docstrings).
+
+# Visiting Vehicle for RPOD analysis
+[vv]
+stl_lm = cylinder_transformed.stl
+stl_thruster = mold_funnel_transformed.stl
+
+# Target Vehicle for RPOD analysis
+[tv]
+stl = inclined_plate_transformed.stl
+
+# surface wall temperature (Kelvin): Tw/T0 = 1.5 (paper Figs. 17-21)
+surface_temp = 300
+
+# proportion of diffuse particle reflections [0, 1]
+sigma = 1
+
+# check plume constraints? 0 or 1
+check_constraints = 0
+
+# max heat flux integral (J/m^2)
+heat_flux_load = inf
+heat_flux_window_size = 1
+
+# max heat flux rate (W/m^2)
+heat_flux = inf
+
+# max pressure load
+normal_pressure_load = inf
+normal_pressure_window_size = inf
+
+# max normal pressure (N/m^2)
+normal_pressure = inf
+
+# max shear pressure (N/m^2)
+shear_pressure = inf
+
+# Plume kinetics and interactions models
+[pm]
+# Gas kinetics model
+kinetics = Simplified
+
+# Gas-surface interaction model
+surface_interaction = Maxwellian
+
+# Jet Firing History
+[jfh]
+jfh = jfh_plume_inclined_plate.A
+
+# Thruster configuration data.
+[tcd]
+# Thruster Configuration File - single head-on thruster, no cant.
+tcf = tcf_1_argon.txt
+
+# Thruster Definition File - argon at the paper conditions.
+tdf = tdf.csv
+
+# Parameters for scaling plume geometry.
+[plume]
+radius = 25
+# ~89 deg: the default 0.436 (25 deg) would clip the plate -- its lower
+# corners sit ~70 deg off-axis at the paper distance. 1.55 rad keeps the
+# gating wedge clear of the whole plate at every sweep pose.
+wedge_theta = 1.55
diff --git a/case/plume/plume_inclined_plate/jfh/generate_jfh_inclined_plate.py b/case/plume/plume_inclined_plate/jfh/generate_jfh_inclined_plate.py
new file mode 100644
index 0000000..249f71d
--- /dev/null
+++ b/case/plume/plume_inclined_plate/jfh/generate_jfh_inclined_plate.py
@@ -0,0 +1,37 @@
+"""Generate the single-firing JFH for the Cai 2016 inclined-plate case.
+
+One firing at the paper geometry (Aerospace 2016, 3(4):43, Section 4): the
+visiting vehicle sits at the origin with an identity DCM, so its single
+thruster (exit at the VV origin, no cant) fires along +X toward the plate
+centered at (4, 0, 0) m. Firing time 1.0 s makes heat_flux_load equal the
+heat-flux rate.
+
+JFH files are always generated by script, never hand-edited. Run from this
+directory:  python generate_jfh_inclined_plate.py
+"""
+
+from pathlib import Path
+
+OUT_NAME = 'jfh_plume_inclined_plate.A'
+
+DCM_IDENTITY = ('1.000000e+00 0.000000e+00 0.000000e+00 '
+                '0.000000e+00 1.000000e+00 0.000000e+00 '
+                '0.000000e+00 0.000000e+00 1.000000e+00')
+
+
+def write_jfh(path, firings):
+    """firings: list of (dt, t, dcm_str, xyz, thrusters)."""
+    lines = [f'offseted    {len(firings)}       0', '       0.000       0.000       0.000']
+    for n, (dt, t, dcm, xyz, thrusters) in enumerate(firings, start=1):
+        xyz_str = ' '.join(f'{v:.9g}' for v in xyz)
+        thr_str = ' '.join(str(i) for i in thrusters)
+        lines.append(f'      {n} {dt:g} {t:g} 0 {dcm} {xyz_str} 1 '
+                     f'{len(thrusters)} {thr_str}')
+    with open(path, 'w', newline='\n') as fh:
+        fh.write('\n'.join(lines) + '\n')
+
+
+if __name__ == '__main__':
+    out_path = Path(__file__).resolve().parent / OUT_NAME
+    write_jfh(out_path, [(0.0, 1.0, DCM_IDENTITY, (0.0, 0.0, 0.0), [1])])
+    print(f'saved {out_path}')
diff --git a/case/plume/plume_inclined_plate/jfh/jfh_plume_inclined_plate.A b/case/plume/plume_inclined_plate/jfh/jfh_plume_inclined_plate.A
new file mode 100644
index 0000000..610bf30
--- /dev/null
+++ b/case/plume/plume_inclined_plate/jfh/jfh_plume_inclined_plate.A
@@ -0,0 +1,3 @@
+offseted    1       0
+       0.000       0.000       0.000
+      1 0 1 0 1.000000e+00 0.000000e+00 0.000000e+00 0.000000e+00 1.000000e+00 0.000000e+00 0.000000e+00 0.000000e+00 1.000000e+00 0 0 0 1 1 1
diff --git a/case/plume/plume_inclined_plate/stl/inclined_plate_transformed.stl b/case/plume/plume_inclined_plate/stl/inclined_plate_transformed.stl
new file mode 100644
index 0000000..6debcc4
Binary files /dev/null and b/case/plume/plume_inclined_plate/stl/inclined_plate_transformed.stl differ
diff --git a/case/plume/plume_inclined_plate/stl/transform_inclined_plate.py b/case/plume/plume_inclined_plate/stl/transform_inclined_plate.py
new file mode 100644
index 0000000..dc6d9be
--- /dev/null
+++ b/case/plume/plume_inclined_plate/stl/transform_inclined_plate.py
@@ -0,0 +1,101 @@
+"""Generate the inclined-plate target mesh for the Cai 2016 verification case.
+
+Builds a single-sided, uniformly triangulated rectangular plate matching the
+paper's Section-4 geometry (Aerospace 2016, 3(4):43): an 8 m x 8 m plate whose
+center sits at (L, 0, 0) = (4, 0, 0) m from the nozzle exit, inclined by
+alpha0 = 60 deg. The thruster fires along +X from a head-on JFH pose (VV at
+the origin, identity DCM), so the global frame coincides with the paper's
+nozzle frame and with pyrpod/plume/CaiImpingement2016.py:
+
+    plate point(s, tau) = center + s * (0, 1, 0) + tau * (cos a0, 0, sin a0)
+
+Every face normal points toward the thruster, (-sin a0, 0, cos a0), which the
+strike pipeline's facing test (surface_dot_plume < 0) requires; the script
+asserts this before saving.
+
+Angle, distance, plate size, and mesh resolution are parametrized for the
+Phase-3 sweep reuse. Defaults reproduce the paper case with 2 * 72^2 = 10368
+faces (~0.11 m elements): contour-quality resolution at a per-face kinetics
+cost that keeps a single firing in the tens of seconds.
+
+Run from this directory:  python transform_inclined_plate.py
+"""
+
+import argparse
+from pathlib import Path
+
+import numpy as np
+from stl import mesh
+
+
+def build_plate_mesh(alpha0_deg=60.0, center=(4.0, 0.0, 0.0),
+                     half_width=4.0, half_height=4.0, n_div=72):
+    """Return a numpy-stl Mesh of the inclined plate.
+
+    Parameters
+    ----------
+    alpha0_deg : float
+        plate inclination angle alpha0 (deg); 90 = normal to the jet axis
+    center : sequence of float
+        plate center in the global/nozzle frame (m)
+    half_width : float
+        semi-width W0 along the horizontal s direction (m)
+    half_height : float
+        semi-length H0 along the inclined tau direction (m)
+    n_div : int
+        quad divisions per axis (faces = 2 * n_div^2)
+    """
+    a0 = np.deg2rad(alpha0_deg)
+    center = np.asarray(center, dtype=float)
+    t_s = np.array([0.0, 1.0, 0.0])
+    t_tau = np.array([np.cos(a0), 0.0, np.sin(a0)])
+    normal = np.array([-np.sin(a0), 0.0, np.cos(a0)])
+
+    s_edges = np.linspace(-half_width, half_width, n_div + 1)
+    tau_edges = np.linspace(-half_height, half_height, n_div + 1)
+
+    def point(s, tau):
+        return center + s * t_s + tau * t_tau
+
+    data = np.zeros(2 * n_div * n_div, dtype=mesh.Mesh.dtype)
+    k = 0
+    for i in range(n_div):
+        for j in range(n_div):
+            p00 = point(s_edges[i], tau_edges[j])
+            p10 = point(s_edges[i + 1], tau_edges[j])
+            p01 = point(s_edges[i], tau_edges[j + 1])
+            p11 = point(s_edges[i + 1], tau_edges[j + 1])
+            # wound so cross(v1-v0, v2-v0) points along `normal`
+            data['vectors'][k] = np.array([p00, p01, p11])
+            data['vectors'][k + 1] = np.array([p00, p11, p10])
+            k += 2
+
+    plate = mesh.Mesh(data)
+    plate.update_normals()
+    unit_normals = plate.get_unit_normals()
+    assert np.allclose(unit_normals, normal, atol=1e-9), (
+        'face normals do not all point toward the thruster')
+    return plate
+
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser(description=__doc__.splitlines()[0])
+    parser.add_argument('--alpha0-deg', type=float, default=60.0)
+    parser.add_argument('--distance', type=float, default=4.0,
+                        help='nozzle-to-plate-center distance L (m)')
+    parser.add_argument('--half-width', type=float, default=4.0)
+    parser.add_argument('--half-height', type=float, default=4.0)
+    parser.add_argument('--n-div', type=int, default=72)
+    parser.add_argument('--out', type=str,
+                        default='inclined_plate_transformed.stl')
+    args = parser.parse_args()
+
+    plate = build_plate_mesh(alpha0_deg=args.alpha0_deg,
+                             center=(args.distance, 0.0, 0.0),
+                             half_width=args.half_width,
+                             half_height=args.half_height,
+                             n_div=args.n_div)
+    out_path = Path(__file__).resolve().parent / args.out
+    plate.save(str(out_path))
+    print(f'saved {out_path} ({len(plate.vectors)} faces, '
+          f'alpha0 = {args.alpha0_deg} deg, L = {args.distance} m)')
diff --git a/case/plume/plume_inclined_plate/tcd/tcf_1_argon.txt b/case/plume/plume_inclined_plate/tcd/tcf_1_argon.txt
new file mode 100644
index 0000000..53e6e0e
--- /dev/null
+++ b/case/plume/plume_inclined_plate/tcd/tcf_1_argon.txt
@@ -0,0 +1,6 @@
+1
+m
+0.000000 0.000000 0.000000
+0.000000 0.000000 0.000000
+T1 ARG 0 0 0 1.000000e+00 0.000000e+00 0.000000e+00 0.000000e+00 1.000000e+00 0.000000e+00 0.000000e+00 0.000000e+00 1.000000e+00
+0
diff --git a/case/plume/plume_inclined_plate/tcd/tdf.csv b/case/plume/plume_inclined_plate/tcd/tdf.csv
new file mode 100644
index 0000000..dc39035
--- /dev/null
+++ b/case/plume/plume_inclined_plate/tcd/tdf.csv
@@ -0,0 +1,2 @@
+#,name,prop,F,isp,MIB,m,mdot,ve,d,R,gamma,Te,rhoe,n
+ARG,CAI2016,argon,1,1,1,1,0.001,577.0684534784414,1.0,208.13,1.6666666666666667,200,6.6329E-06,1.0E+20
diff --git a/case/plume/plume_inclined_plate_sweep/config.ini b/case/plume/plume_inclined_plate_sweep/config.ini
new file mode 100644
index 0000000..edd5020
--- /dev/null
+++ b/case/plume/plume_inclined_plate_sweep/config.ini
@@ -0,0 +1,72 @@
+# Cai 2016 inclined-plate SWEEP case (Aerospace 3(4):43, Section 4): the
+# paper's 60 deg 8 m x 8 m plate (argon round jet, D = 1 m, S0 = 2.0, T0 =
+# 200 K, Tw = 300 K, fully diffuse), swept over 19 approach angles x 5
+# stand-off distances (95 firings; jfh_inclined_plate_sweep.A). Driven by
+# scripts/inclined_plate_sweep_study.py, which writes per-pose strikes to
+# results/strikes/firing-<i>.vtu. Geometry assets are generated by the
+# scripts in stl/ and jfh/ (see their docstrings). The single paper pose
+# lives in the sibling case plume_inclined_plate (rpod_integration_test_07);
+# the flat-plate reframing in plume_flat_plate_sweep (rpod_verification_test_06).
+
+# Visiting Vehicle for RPOD analysis
+[vv]
+stl_lm = cylinder_transformed.stl
+stl_thruster = mold_funnel_transformed.stl
+
+# Target Vehicle for RPOD analysis
+[tv]
+stl = inclined_plate_transformed.stl
+
+# surface wall temperature (Kelvin): Tw/T0 = 1.5 (paper Figs. 17-21)
+surface_temp = 300
+
+# proportion of diffuse particle reflections [0, 1]
+sigma = 1
+
+# check plume constraints? 0 or 1
+check_constraints = 0
+
+# max heat flux integral (J/m^2)
+heat_flux_load = inf
+heat_flux_window_size = 1
+
+# max heat flux rate (W/m^2)
+heat_flux = inf
+
+# max pressure load
+normal_pressure_load = inf
+normal_pressure_window_size = inf
+
+# max normal pressure (N/m^2)
+normal_pressure = inf
+
+# max shear pressure (N/m^2)
+shear_pressure = inf
+
+# Plume kinetics and interactions models
+[pm]
+# Gas kinetics model
+kinetics = Simplified
+
+# Gas-surface interaction model
+surface_interaction = Maxwellian
+
+# Jet Firing History
+[jfh]
+jfh = jfh_inclined_plate_sweep.A
+
+# Thruster configuration data.
+[tcd]
+# Thruster Configuration File - single head-on thruster, no cant.
+tcf = tcf_1_argon.txt
+
+# Thruster Definition File - argon at the paper conditions.
+tdf = tdf.csv
+
+# Parameters for scaling plume geometry.
+[plume]
+radius = 25
+# ~89 deg: the default 0.436 (25 deg) would clip the plate -- its lower
+# corners sit ~70 deg off-axis at the paper distance. 1.55 rad keeps the
+# gating wedge clear of the whole plate at every sweep pose.
+wedge_theta = 1.55
diff --git a/case/plume/plume_inclined_plate_sweep/jfh/generate_jfh_inclined_plate.py b/case/plume/plume_inclined_plate_sweep/jfh/generate_jfh_inclined_plate.py
new file mode 100644
index 0000000..249f71d
--- /dev/null
+++ b/case/plume/plume_inclined_plate_sweep/jfh/generate_jfh_inclined_plate.py
@@ -0,0 +1,37 @@
+"""Generate the single-firing JFH for the Cai 2016 inclined-plate case.
+
+One firing at the paper geometry (Aerospace 2016, 3(4):43, Section 4): the
+visiting vehicle sits at the origin with an identity DCM, so its single
+thruster (exit at the VV origin, no cant) fires along +X toward the plate
+centered at (4, 0, 0) m. Firing time 1.0 s makes heat_flux_load equal the
+heat-flux rate.
+
+JFH files are always generated by script, never hand-edited. Run from this
+directory:  python generate_jfh_inclined_plate.py
+"""
+
+from pathlib import Path
+
+OUT_NAME = 'jfh_plume_inclined_plate.A'
+
+DCM_IDENTITY = ('1.000000e+00 0.000000e+00 0.000000e+00 '
+                '0.000000e+00 1.000000e+00 0.000000e+00 '
+                '0.000000e+00 0.000000e+00 1.000000e+00')
+
+
+def write_jfh(path, firings):
+    """firings: list of (dt, t, dcm_str, xyz, thrusters)."""
+    lines = [f'offseted    {len(firings)}       0', '       0.000       0.000       0.000']
+    for n, (dt, t, dcm, xyz, thrusters) in enumerate(firings, start=1):
+        xyz_str = ' '.join(f'{v:.9g}' for v in xyz)
+        thr_str = ' '.join(str(i) for i in thrusters)
+        lines.append(f'      {n} {dt:g} {t:g} 0 {dcm} {xyz_str} 1 '
+                     f'{len(thrusters)} {thr_str}')
+    with open(path, 'w', newline='\n') as fh:
+        fh.write('\n'.join(lines) + '\n')
+
+
+if __name__ == '__main__':
+    out_path = Path(__file__).resolve().parent / OUT_NAME
+    write_jfh(out_path, [(0.0, 1.0, DCM_IDENTITY, (0.0, 0.0, 0.0), [1])])
+    print(f'saved {out_path}')
diff --git a/case/plume/plume_inclined_plate_sweep/jfh/generate_sweep_jfh.py b/case/plume/plume_inclined_plate_sweep/jfh/generate_sweep_jfh.py
new file mode 100644
index 0000000..a8e574f
--- /dev/null
+++ b/case/plume/plume_inclined_plate_sweep/jfh/generate_sweep_jfh.py
@@ -0,0 +1,101 @@
+"""Generate the ONE sweep JFH for the Phase-3 angle x distance study.
+
+The plate is STATIONARY (target vehicles do not move): the visiting vehicle
+is swept instead. For each firing the VV (single thruster at the VV origin,
+no cant) is placed on the arc of radius L about the plate center
+C = (4, 0, 0), with the thruster axis aimed at C and the JFH DCM set so the
+pipeline's plume normal (first column of the DCM, with the identity TCF)
+points along that axis.
+
+Pose parametrization, all in the plate's tilt plane (global X-Z):
+
+    d_hat(alpha) = cos(alpha) * n_hat + sin(alpha) * t_hat
+    VV position  = C + L * d_hat(alpha),  thruster axis = -d_hat(alpha)
+
+where n_hat = (-sin 60, 0, cos 60) is the plate normal facing the nozzle
+side and t_hat = (cos 60, 0, sin 60) the plate's inclined tangent.
+alpha = 0 is HEAD-ON (thruster axis along the plate normal; the paper's
+alpha0 = 90 deg); the sign is the tilt direction, mapping
+alpha_paper = 90 deg - |alpha|. Results must be mirror-symmetric in
++/-alpha (the plate is square); +/-90 deg is edge-on/degenerate and is
+kept to confirm ~zero struck faces.
+
+Sweep: alpha from -90 to +90 deg in 10 deg steps (19 angles) x
+L/D in {2, 4, 6, 8, 10} (D = 1 m), enumerated distance-major:
+firing index = i_L * 19 + i_alpha + 1. 95 firings total, firing time
+1.0 s each.
+
+JFH files are always generated by script, never hand-edited. Run from this
+directory:  python generate_sweep_jfh.py
+"""
+
+from pathlib import Path
+
+import numpy as np
+
+from generate_jfh_inclined_plate import write_jfh
+
+OUT_NAME = 'jfh_inclined_plate_sweep.A'
+
+PLATE_CENTER = np.array([4.0, 0.0, 0.0])
+ALPHA0_DEG = 60.0
+ALPHAS_DEG = np.arange(-90.0, 90.0 + 1e-9, 10.0)
+L_OVER_D = [2.0, 4.0, 6.0, 8.0, 10.0]
+
+
+def pose_for(alpha_deg, L, plate_center=PLATE_CENTER, alpha0_deg=ALPHA0_DEG):
+    """(vv_position, dcm) for one sweep firing; dcm's first column is the
+    thruster axis (see the pipeline's plume-normal convention).
+
+    plate_center / alpha0_deg place the whole {plate + swept-arc} rig in the
+    global frame. They are physics-invariant (every relative incidence, and
+    thus every coefficient, is preserved under this rigid rotation +
+    translation) -- a flat alpha0 = 0 variant is a pure visualization
+    reframing of the same case. They must match the target STL's own
+    center/tilt (stl/transform_inclined_plate.py) and the analysis constants
+    (tests/rpod/rpod_verification_test_06.py)."""
+    a0 = np.deg2rad(alpha0_deg)
+    n_hat = np.array([-np.sin(a0), 0.0, np.cos(a0)])
+    t_hat = np.array([np.cos(a0), 0.0, np.sin(a0)])
+    alpha = np.deg2rad(alpha_deg)
+    d_hat = np.cos(alpha) * n_hat + np.sin(alpha) * t_hat
+    position = np.asarray(plate_center, dtype=float) + L * d_hat
+    axis = -d_hat                       # aimed at the plate center
+    # right-handed triad; the axis always lies in the X-Z plane, so the
+    # global Y axis is a valid second column
+    c1 = np.array([0.0, 1.0, 0.0])
+    c2 = np.cross(axis, c1)
+    dcm = np.column_stack([axis, c1, c2])
+    return position, dcm
+
+
+def dcm_string(dcm):
+    return ' '.join(f'{v:.6e}' for v in np.asarray(dcm).ravel())
+
+
+if __name__ == '__main__':
+    import argparse
+
+    parser = argparse.ArgumentParser(description=__doc__.splitlines()[0])
+    parser.add_argument('--alpha0-deg', type=float, default=ALPHA0_DEG,
+                        help='global-frame plate tilt (deg); physics-'
+                             'invariant, must match the target STL')
+    parser.add_argument('--distance', type=float, default=PLATE_CENTER[0],
+                        help='plate-center X in the global frame (m); the '
+                             'center is (distance, 0, 0)')
+    parser.add_argument('--out', type=str, default=OUT_NAME,
+                        help='output JFH filename in this jfh/ folder')
+    args = parser.parse_args()
+
+    plate_center = np.array([args.distance, 0.0, 0.0])
+    firings = []
+    for L in L_OVER_D:
+        for alpha_deg in ALPHAS_DEG:
+            position, dcm = pose_for(alpha_deg, L, plate_center=plate_center,
+                                     alpha0_deg=args.alpha0_deg)
+            firings.append((0.0, 1.0, dcm_string(dcm), tuple(position), [1]))
+    out_path = Path(__file__).resolve().parent / args.out
+    write_jfh(out_path, firings)
+    print(f'saved {out_path} ({len(firings)} firings: '
+          f'{len(ALPHAS_DEG)} angles x {len(L_OVER_D)} distances, '
+          f'alpha0 = {args.alpha0_deg} deg, center X = {args.distance} m)')
diff --git a/case/plume/plume_inclined_plate_sweep/jfh/jfh_inclined_plate_sweep.A b/case/plume/plume_inclined_plate_sweep/jfh/jfh_inclined_plate_sweep.A
new file mode 100644
index 0000000..3889cef
--- /dev/null
+++ b/case/plume/plume_inclined_plate_sweep/jfh/jfh_inclined_plate_sweep.A
@@ -0,0 +1,97 @@
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+      79 0 1 0 7.660444e-01 0.000000e+00 -6.427876e-01 -0.000000e+00 1.000000e+00 0.000000e+00 6.427876e-01 0.000000e+00 7.660444e-01 -3.66044443 0 -6.4278761 1 1 1
+      80 0 1 0 8.660254e-01 0.000000e+00 -5.000000e-01 -0.000000e+00 1.000000e+00 0.000000e+00 5.000000e-01 0.000000e+00 8.660254e-01 -4.66025404 0 -5 1 1 1
+      81 0 1 0 9.396926e-01 0.000000e+00 -3.420201e-01 -0.000000e+00 1.000000e+00 0.000000e+00 3.420201e-01 0.000000e+00 9.396926e-01 -5.39692621 0 -3.42020143 1 1 1
+      82 0 1 0 9.848078e-01 0.000000e+00 -1.736482e-01 -0.000000e+00 1.000000e+00 0.000000e+00 1.736482e-01 0.000000e+00 9.848078e-01 -5.84807753 0 -1.73648178 1 1 1
+      83 0 1 0 1.000000e+00 0.000000e+00 2.220446e-16 -0.000000e+00 1.000000e+00 -0.000000e+00 -2.220446e-16 0.000000e+00 1.000000e+00 -6 0 2.22044605e-15 1 1 1
+      84 0 1 0 9.848078e-01 0.000000e+00 1.736482e-01 -0.000000e+00 1.000000e+00 -0.000000e+00 -1.736482e-01 0.000000e+00 9.848078e-01 -5.84807753 0 1.73648178 1 1 1
+      85 0 1 0 9.396926e-01 0.000000e+00 3.420201e-01 -0.000000e+00 1.000000e+00 -0.000000e+00 -3.420201e-01 0.000000e+00 9.396926e-01 -5.39692621 0 3.42020143 1 1 1
+      86 0 1 0 8.660254e-01 0.000000e+00 5.000000e-01 -0.000000e+00 1.000000e+00 -0.000000e+00 -5.000000e-01 0.000000e+00 8.660254e-01 -4.66025404 0 5 1 1 1
+      87 0 1 0 7.660444e-01 0.000000e+00 6.427876e-01 -0.000000e+00 1.000000e+00 -0.000000e+00 -6.427876e-01 0.000000e+00 7.660444e-01 -3.66044443 0 6.4278761 1 1 1
+      88 0 1 0 6.427876e-01 0.000000e+00 7.660444e-01 -0.000000e+00 1.000000e+00 -0.000000e+00 -7.660444e-01 0.000000e+00 6.427876e-01 -2.4278761 0 7.66044443 1 1 1
+      89 0 1 0 5.000000e-01 0.000000e+00 8.660254e-01 -0.000000e+00 1.000000e+00 -0.000000e+00 -8.660254e-01 0.000000e+00 5.000000e-01 -1 0 8.66025404 1 1 1
+      90 0 1 0 3.420201e-01 0.000000e+00 9.396926e-01 -0.000000e+00 1.000000e+00 -0.000000e+00 -9.396926e-01 0.000000e+00 3.420201e-01 0.579798567 0 9.39692621 1 1 1
+      91 0 1 0 1.736482e-01 0.000000e+00 9.848078e-01 -0.000000e+00 1.000000e+00 -0.000000e+00 -9.848078e-01 0.000000e+00 1.736482e-01 2.26351822 0 9.84807753 1 1 1
+      92 0 1 0 -0.000000e+00 0.000000e+00 1.000000e+00 -0.000000e+00 1.000000e+00 0.000000e+00 -1.000000e+00 0.000000e+00 0.000000e+00 4 0 10 1 1 1
+      93 0 1 0 -1.736482e-01 0.000000e+00 9.848078e-01 -0.000000e+00 1.000000e+00 0.000000e+00 -9.848078e-01 0.000000e+00 -1.736482e-01 5.73648178 0 9.84807753 1 1 1
+      94 0 1 0 -3.420201e-01 0.000000e+00 9.396926e-01 -0.000000e+00 1.000000e+00 0.000000e+00 -9.396926e-01 0.000000e+00 -3.420201e-01 7.42020143 0 9.39692621 1 1 1
+      95 0 1 0 -5.000000e-01 0.000000e+00 8.660254e-01 -0.000000e+00 1.000000e+00 0.000000e+00 -8.660254e-01 0.000000e+00 -5.000000e-01 9 0 8.66025404 1 1 1
diff --git a/case/plume/plume_inclined_plate_sweep/stl/inclined_plate_transformed.stl b/case/plume/plume_inclined_plate_sweep/stl/inclined_plate_transformed.stl
new file mode 100644
index 0000000..6debcc4
Binary files /dev/null and b/case/plume/plume_inclined_plate_sweep/stl/inclined_plate_transformed.stl differ
diff --git a/case/plume/plume_inclined_plate_sweep/stl/transform_inclined_plate.py b/case/plume/plume_inclined_plate_sweep/stl/transform_inclined_plate.py
new file mode 100644
index 0000000..dc6d9be
--- /dev/null
+++ b/case/plume/plume_inclined_plate_sweep/stl/transform_inclined_plate.py
@@ -0,0 +1,101 @@
+"""Generate the inclined-plate target mesh for the Cai 2016 verification case.
+
+Builds a single-sided, uniformly triangulated rectangular plate matching the
+paper's Section-4 geometry (Aerospace 2016, 3(4):43): an 8 m x 8 m plate whose
+center sits at (L, 0, 0) = (4, 0, 0) m from the nozzle exit, inclined by
+alpha0 = 60 deg. The thruster fires along +X from a head-on JFH pose (VV at
+the origin, identity DCM), so the global frame coincides with the paper's
+nozzle frame and with pyrpod/plume/CaiImpingement2016.py:
+
+    plate point(s, tau) = center + s * (0, 1, 0) + tau * (cos a0, 0, sin a0)
+
+Every face normal points toward the thruster, (-sin a0, 0, cos a0), which the
+strike pipeline's facing test (surface_dot_plume < 0) requires; the script
+asserts this before saving.
+
+Angle, distance, plate size, and mesh resolution are parametrized for the
+Phase-3 sweep reuse. Defaults reproduce the paper case with 2 * 72^2 = 10368
+faces (~0.11 m elements): contour-quality resolution at a per-face kinetics
+cost that keeps a single firing in the tens of seconds.
+
+Run from this directory:  python transform_inclined_plate.py
+"""
+
+import argparse
+from pathlib import Path
+
+import numpy as np
+from stl import mesh
+
+
+def build_plate_mesh(alpha0_deg=60.0, center=(4.0, 0.0, 0.0),
+                     half_width=4.0, half_height=4.0, n_div=72):
+    """Return a numpy-stl Mesh of the inclined plate.
+
+    Parameters
+    ----------
+    alpha0_deg : float
+        plate inclination angle alpha0 (deg); 90 = normal to the jet axis
+    center : sequence of float
+        plate center in the global/nozzle frame (m)
+    half_width : float
+        semi-width W0 along the horizontal s direction (m)
+    half_height : float
+        semi-length H0 along the inclined tau direction (m)
+    n_div : int
+        quad divisions per axis (faces = 2 * n_div^2)
+    """
+    a0 = np.deg2rad(alpha0_deg)
+    center = np.asarray(center, dtype=float)
+    t_s = np.array([0.0, 1.0, 0.0])
+    t_tau = np.array([np.cos(a0), 0.0, np.sin(a0)])
+    normal = np.array([-np.sin(a0), 0.0, np.cos(a0)])
+
+    s_edges = np.linspace(-half_width, half_width, n_div + 1)
+    tau_edges = np.linspace(-half_height, half_height, n_div + 1)
+
+    def point(s, tau):
+        return center + s * t_s + tau * t_tau
+
+    data = np.zeros(2 * n_div * n_div, dtype=mesh.Mesh.dtype)
+    k = 0
+    for i in range(n_div):
+        for j in range(n_div):
+            p00 = point(s_edges[i], tau_edges[j])
+            p10 = point(s_edges[i + 1], tau_edges[j])
+            p01 = point(s_edges[i], tau_edges[j + 1])
+            p11 = point(s_edges[i + 1], tau_edges[j + 1])
+            # wound so cross(v1-v0, v2-v0) points along `normal`
+            data['vectors'][k] = np.array([p00, p01, p11])
+            data['vectors'][k + 1] = np.array([p00, p11, p10])
+            k += 2
+
+    plate = mesh.Mesh(data)
+    plate.update_normals()
+    unit_normals = plate.get_unit_normals()
+    assert np.allclose(unit_normals, normal, atol=1e-9), (
+        'face normals do not all point toward the thruster')
+    return plate
+
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser(description=__doc__.splitlines()[0])
+    parser.add_argument('--alpha0-deg', type=float, default=60.0)
+    parser.add_argument('--distance', type=float, default=4.0,
+                        help='nozzle-to-plate-center distance L (m)')
+    parser.add_argument('--half-width', type=float, default=4.0)
+    parser.add_argument('--half-height', type=float, default=4.0)
+    parser.add_argument('--n-div', type=int, default=72)
+    parser.add_argument('--out', type=str,
+                        default='inclined_plate_transformed.stl')
+    args = parser.parse_args()
+
+    plate = build_plate_mesh(alpha0_deg=args.alpha0_deg,
+                             center=(args.distance, 0.0, 0.0),
+                             half_width=args.half_width,
+                             half_height=args.half_height,
+                             n_div=args.n_div)
+    out_path = Path(__file__).resolve().parent / args.out
+    plate.save(str(out_path))
+    print(f'saved {out_path} ({len(plate.vectors)} faces, '
+          f'alpha0 = {args.alpha0_deg} deg, L = {args.distance} m)')
diff --git a/case/plume/plume_inclined_plate_sweep/tcd/tcf_1_argon.txt b/case/plume/plume_inclined_plate_sweep/tcd/tcf_1_argon.txt
new file mode 100644
index 0000000..53e6e0e
--- /dev/null
+++ b/case/plume/plume_inclined_plate_sweep/tcd/tcf_1_argon.txt
@@ -0,0 +1,6 @@
+1
+m
+0.000000 0.000000 0.000000
+0.000000 0.000000 0.000000
+T1 ARG 0 0 0 1.000000e+00 0.000000e+00 0.000000e+00 0.000000e+00 1.000000e+00 0.000000e+00 0.000000e+00 0.000000e+00 1.000000e+00
+0
diff --git a/case/plume/plume_inclined_plate_sweep/tcd/tdf.csv b/case/plume/plume_inclined_plate_sweep/tcd/tdf.csv
new file mode 100644
index 0000000..dc39035
--- /dev/null
+++ b/case/plume/plume_inclined_plate_sweep/tcd/tdf.csv
@@ -0,0 +1,2 @@
+#,name,prop,F,isp,MIB,m,mdot,ve,d,R,gamma,Te,rhoe,n
+ARG,CAI2016,argon,1,1,1,1,0.001,577.0684534784414,1.0,208.13,1.6666666666666667,200,6.6329E-06,1.0E+20
diff --git a/pyrpod/plume/CaiImpingement2016.py b/pyrpod/plume/CaiImpingement2016.py
new file mode 100644
index 0000000..3a6a6dc
--- /dev/null
+++ b/pyrpod/plume/CaiImpingement2016.py
@@ -0,0 +1,1070 @@
+"""
+Verification reference for Cai 2016 (inclined-plate plume impingement).
+
+Cai, C., "Gaskinetic Modeling on Dilute Gaseous Plume Impingement Flows,"
+Aerospace 2016, 3(4), 43, doi:10.3390/aerospace3040043.
+
+This module is a PLAIN-FUNCTION reference implementation of the paper's exact
+solutions -- the single source of truth for every Cai-2016 verification
+figure in tests/plume. It covers:
+
+* Section 4 surface properties: diffuse-plate Cp/Cf1/Cf2/Cq (Eqs. 9-13),
+  specular Cp (Eq. 14), Eq. 15 plate averages (Figs. 17-21);
+* Section 3, the 2D slot jet on an inclined planar plate: surface
+  coefficients Cp,d/Cf,d/Cq,d and Cp,s (Eqs. 2-4, 8; Figs. 7-10) and the
+  combined jet + plate flowfield temperature (Figs. 5-6);
+* Section 4 flowfield pressure in the vertical Y = 0 plane with the plate
+  contribution, diffuse and specular (Figs. 15-16).
+
+The free-jet field factors of the 3D solutions are imported from
+pyrpod/plume/RarefiedPlumeGasKinetics.py (the Cai & Wang 2012 plume model
+of record) rather than re-derived, so the two implementations can never
+drift apart. This module exists to verify PyRPOD's plume modeling against
+the paper -- it is NOT a new plume model class and must not be wired into
+the strike pipeline.
+
+Section-3 validation geometry (interpretation note): this paper does not
+print the 2D case's numbers (they come from its ref. [39], Cai & He 2016);
+they are read off Figs. 1 and 5-10: slot height 2H, center-to-center
+distance L = 4*(2H), plate semi-width W = 5*(2H), Tw/T0 = 1.5, with
+(S0, alpha0) per figure legend. The plotted axes are X/(2H) and s/(2H).
+
+Flowfield figures (5-6, 15-16) evaluate the analytic solutions on the
+whole X > 0 half-plane with no plate shadowing, exactly as the paper's
+contours do (Fig. 6's specular temperature field is symmetric about the
+plate line only under this convention); the diffuse plate emits from its
+front face only, so behind-plate points carry the jet-only continuation.
+Specular-plate effects use the paper's virtual-nozzle construction; the
+virtual exit is built by literal mirror reflection of the real exit about
+the plate plane, which reproduces Eq. 7 (2D) and the printed 3D virtual
+position (L(1 - cos 2a0), 0, -L sin 2a0). The virtual DRIFT is the mirror
+image U0*(cos 2a0, 0, sin 2a0); the paper's prose sign
+(-U0 cos 2a0, ..., -U0 sin 2a0) is the velocity-space DOMAIN VERTEX -U0'
+of Fig. 14, not the drift (same resolution style as the 2012 Eq. 7 typo
+note in RarefiedPlumeGasKinetics).
+
+Geometry and symbol conventions (paper Fig. 11)
+-----------------------------------------------
+* Nozzle exit: disk of radius R_0 centered at the origin in the Y-Z plane;
+  bulk flow along +X with speed ratio S_0 = U_0 / sqrt(2*R*T_0).
+* Plate: center at (L, 0, 0), inclination angle alpha_0. Local plate
+  coordinates (s, tau) map to global coordinates as
+      X = L + tau*cos(alpha_0),  Y = s,  Z = tau*sin(alpha_0),
+  i.e. tau runs along the inclined direction in the X-Z plane
+  (|tau| <= H_0) and s along the horizontal Y direction (|s| <= W_0).
+  The plate unit normal facing the nozzle is (-sin(alpha_0), 0, cos(alpha_0));
+  alpha_0 = 90 deg is a plate normal to the jet axis.
+* Exit-disk integration point: E = (0, r*cos(theta), r*sin(theta)), so that
+  Eq. 10 reads Q^2 = |P - E|^2 / X^2 >= 1 (NOTE: unlike the 2012 paper's
+  special factor Q_2012 = X^2/|P-E|^2 <= 1, the 2016 paper's Q is the
+  reciprocal square root: a = S_0/Q = S_0*sqrt(Q_2012), the speed ratio
+  projected on the ray from E to the plate point).
+* B1 = (Z - r*sin(theta))/X, B2 = (Y - r*cos(theta))/X, and
+  mu = sin(alpha_0) - B1*cos(alpha_0) = -(ray direction . outward normal)*Q,
+  so mu > 0 exactly when the ray from E strikes the FRONT face of the plate.
+
+Overflow safety: every Appendix-A factor A_k(a) carries a e^(a^2) term while
+the solutions carry e^(-S_0^2); since a = S_0/Q <= S_0, the two are combined
+into e^(a^2 - S_0^2) <= 1 (the same scaling style used by get_K_factor in
+RarefiedPlumeGasKinetics.py), so no term can overflow for large S_0.
+
+Diffuse-wall re-emission density n_w (interpretation note)
+----------------------------------------------------------
+The paper states n_w(s, tau) is set by non-penetration at the plate but does
+not print the 3D expression (its refs. [35, 37] give the 2D principle). The
+3D analog is derived here from first principles: the incoming number flux
+from the jet at plate point P,
+
+    Phi_in = n_0 * e^(-S_0^2) / (pi^(3/2) * beta_0 * X^2)
+             * Int_disk (A_1/Q^4) * mu * r dr dtheta,
+
+must equal the effusion flux of the wall Maxwellian at T_w,
+Phi_out = n_w * sqrt(R*T_w/(2*pi)) = n_w / (2*sqrt(pi)*beta_w), giving
+
+    n_w/n_0 = (2/sqrt(eps)) * e^(-S_0^2)/(pi * X^2)
+              * Int_disk (A_1/Q^4) * mu * r dr dtheta,   eps = T_w/T_0.
+
+This is exactly "the A_1-analog exit-disk integral": the same reduction that
+produces Eq. 9 (pressure ~ A_2/Q^5 * mu^2) and Eq. 13 (energy flux ~
+A_3/Q^4 * mu) yields number flux ~ A_1/Q^4 * mu. Validation against the
+paper's figures: with this n_w the center-region magnitudes reproduce
+Figs. 17-18 (diffuse Cp peaks just above the 0.2 innermost contour and
+specular Cp above 0.3, specular slightly higher at the impingement center,
+as the paper notes), and the wall energy-emission term of Eq. 13,
+-eps^(3/2) * (n_w/n_0) / (sqrt(pi)*S_0^3), is the effusion energy flux
+(2*k*T_w per emitted molecule) of the SAME n_w -- an independent
+consistency check between Eqs. 9 and 13.
+
+Front-face visibility clamp
+---------------------------
+The printed Eqs. 9-13 integrate over the whole exit disk. For the paper's
+validation geometry (alpha_0 = 60 deg, L = 4D) every disk point sees the
+front face (mu > 0 everywhere), so clamping is a no-op there. For grazing
+geometries (small alpha_0 and/or small L, reached in the sweep study) part
+of the disk falls behind the plate plane; those rays cannot deposit flux on
+the front face, so integrand contributions with mu <= 0 are dropped. This
+extends the formulas continuously to the grazing limit instead of letting
+unphysical negative-flux contributions enter.
+
+All returned coefficients use the paper's normalization: pressure and shear
+by n_0*m*U_0^2/2, heat flux by n_0*m*U_0^3/2 (m = molecular mass); they are
+dimensionless and independent of n_0.
+"""
+
+import numpy as np
+from scipy.special import erf
+
+from pyrpod.plume.RarefiedPlumeGasKinetics import (
+    get_K_factor,
+    get_M_factor,
+    get_N_factor,
+    get_Q_full,
+)
+
+#: Gauss-Legendre order per axis for the exit-disk integrals. The integrand
+#: is analytic on the compact disk (denominators bounded below by X^2 > 0),
+#: so convergence is geometric; 48 nodes reach ~1e-12 for every geometry in
+#: the study (verified by the order-doubling test in run_sanity_checks).
+DEFAULT_ORDER = 48
+
+
+def _scaled_A_factors(a, S_0):
+    '''
+        Appendix-A factors A_1, A_2, A_3 evaluated at a and pre-multiplied
+        by the solutions' e^(-S_0^2) prefactor, combined overflow-safely
+        into e^(a^2 - S_0^2) <= 1 (a = S_0/Q <= S_0).
+
+        Parameters
+        ----------
+        a : ndarray
+            projected speed ratio S_0/Q along each disk-to-plate ray
+        S_0 : float
+            molecular speed ratio at the nozzle exit
+
+        Returns
+        -------
+        tuple of ndarray
+            (e^(-S_0^2)*A_1(a), e^(-S_0^2)*A_2(a), e^(-S_0^2)*A_3(a))
+    '''
+    erf_term = 0.25 * np.sqrt(np.pi) * (1 + erf(a)) * np.exp(a ** 2 - S_0 ** 2)
+    exp_term = np.exp(-S_0 ** 2)
+    A1 = erf_term * (3 * a + 2 * a ** 3) + exp_term * (0.5 + 0.5 * a ** 2)
+    A2 = (erf_term * (1.5 + 6 * a ** 2 + 2 * a ** 4)
+          + exp_term * (1.25 * a + 0.5 * a ** 3))
+    A3 = (erf_term * (2 * a ** 5 + 10 * a ** 3 + 7.5 * a)
+          + exp_term * (0.5 * a ** 4 + 2.25 * a ** 2 + 1.0))
+    return A1, A2, A3
+
+
+def plate_point_coords(s, tau, alpha_0, L):
+    '''
+        Global coordinates of plate points from local plate coordinates
+        (see module docstring for the convention).
+
+        Parameters
+        ----------
+        s, tau : float or ndarray
+            local plate coordinates (m); broadcast together
+        alpha_0 : float
+            plate inclination angle (rad)
+        L : float
+            center-to-center nozzle-to-plate distance (m)
+
+        Returns
+        -------
+        tuple of ndarray
+            (X, Y, Z) global coordinates (m)
+    '''
+    s = np.asarray(s, dtype=float)
+    tau = np.asarray(tau, dtype=float)
+    X = L + tau * np.cos(alpha_0)
+    Y = np.broadcast_to(s, np.broadcast(s, tau).shape).copy()
+    Z = tau * np.sin(alpha_0)
+    return X, Y, Z
+
+
+def surface_coefficients(X, Y, Z, S_0, alpha_0, eps, R_0,
+                         order=DEFAULT_ORDER, chunk=256):
+    '''
+        Exact surface coefficients of Cai 2016 Eqs. 9-14 at global plate
+        points (X, Y, Z), vectorized with tensor-product Gauss-Legendre
+        quadrature over the exit disk (r in [0, R_0], theta in [0, 2*pi]).
+
+        Points with X <= 0 are behind the exit plane: the collisionless jet
+        carries no molecules there, so every coefficient is 0.
+
+        Parameters
+        ----------
+        X, Y, Z : ndarray
+            global plate-point coordinates (m); flattened internally,
+            outputs keep the input shape
+        S_0 : float
+            exit speed ratio
+        alpha_0 : float
+            plate inclination angle (rad)
+        eps : float
+            wall-to-exit temperature ratio T_w/T_0
+        R_0 : float
+            nozzle exit radius (m)
+        order : int
+            Gauss-Legendre nodes per axis (see DEFAULT_ORDER)
+        chunk : int
+            plate points evaluated per vectorized block (memory control)
+
+        Returns
+        -------
+        dict of ndarray
+            'Cp_d'  : diffuse-plate pressure coefficient [Eq. 9]
+            'Cf1_d' : diffuse shear along the inclined direction [Eq. 11]
+            'Cf2_d' : diffuse shear along the horizontal (Y) [Eq. 12]
+            'Cq_d'  : diffuse heat-flux coefficient [Eq. 13]
+            'Cp_s'  : specular-plate pressure coefficient [Eq. 14]
+            'nw'    : wall re-emission density ratio n_w/n_0 (see docstring)
+    '''
+    X = np.asarray(X, dtype=float)
+    shape = X.shape
+    Xf = X.ravel()
+    Yf = np.asarray(Y, dtype=float).ravel()
+    Zf = np.asarray(Z, dtype=float).ravel()
+
+    nodes, weights = np.polynomial.legendre.leggauss(order)
+    r = 0.5 * R_0 * (nodes + 1)
+    w_r = 0.5 * R_0 * weights
+    th = np.pi * (nodes + 1)
+    w_th = np.pi * weights
+    Rn, Tn = np.meshgrid(r, th, indexing='ij')
+    WR = np.outer(w_r, w_th) * Rn          # quadrature weight * r (Jacobian)
+    Ey = Rn * np.cos(Tn)                   # exit-disk point (0, Ey, Ez)
+    Ez = Rn * np.sin(Tn)
+
+    sin_a, cos_a = np.sin(alpha_0), np.cos(alpha_0)
+    sin_2a, cos_2a = np.sin(2 * alpha_0), np.cos(2 * alpha_0)
+
+    n_pts = Xf.size
+    I_p = np.zeros(n_pts)
+    I_f1 = np.zeros(n_pts)
+    I_f2 = np.zeros(n_pts)
+    I_q = np.zeros(n_pts)
+    I_n = np.zeros(n_pts)
+    ahead = Xf > 0.0
+
+    idx_all = np.nonzero(ahead)[0]
+    for start in range(0, idx_all.size, chunk):
+        idx = idx_all[start:start + chunk]
+        Xc = Xf[idx][:, None, None]
+        Yc = Yf[idx][:, None, None]
+        Zc = Zf[idx][:, None, None]
+
+        dy = Yc - Ey
+        dz = Zc - Ez
+        Q2 = (Xc ** 2 + dy ** 2 + dz ** 2) / Xc ** 2   # Eq. 10
+        Q = np.sqrt(Q2)
+        a = S_0 / Q
+        B1 = dz / Xc
+        B2 = dy / Xc
+        mu = sin_a - B1 * cos_a
+        front = mu > 0.0                    # front-face visibility clamp
+        mu_p = np.where(front, mu, 0.0)
+
+        A1, A2, A3 = _scaled_A_factors(a, S_0)
+        inv_Q4 = 1.0 / (Q2 * Q2)
+        inv_Q5 = inv_Q4 / Q
+
+        I_p[idx] = np.sum(WR * A2 * inv_Q5 * mu_p ** 2, axis=(1, 2))
+        I_f1[idx] = np.sum(
+            WR * A2 * inv_Q5
+            * (0.5 * (1 - B1 ** 2) * sin_2a - B1 * cos_2a)
+            * front, axis=(1, 2))
+        I_f2[idx] = np.sum(WR * A2 * B2 * inv_Q5 * mu_p, axis=(1, 2))
+        I_q[idx] = np.sum(WR * A3 * inv_Q4 * mu_p, axis=(1, 2))
+        I_n[idx] = np.sum(WR * A1 * inv_Q4 * mu_p, axis=(1, 2))
+
+    with np.errstate(divide='ignore', invalid='ignore'):
+        pref = np.where(ahead, 1.0 / (np.pi ** 1.5 * Xf ** 2), 0.0)
+        pref_pi = np.where(ahead, 1.0 / (np.pi * Xf ** 2), 0.0)
+
+    Cp_jet = (2.0 / S_0 ** 2) * pref * I_p
+    Cf1 = (2.0 / S_0 ** 2) * pref * I_f1
+    Cf2 = (2.0 / S_0 ** 2) * pref * I_f2
+    nw = (2.0 / np.sqrt(eps)) * pref_pi * I_n
+    Cq = (pref_pi * I_q - eps ** 1.5 * nw) / (np.sqrt(np.pi) * S_0 ** 3)
+    Cp_d = Cp_jet + eps / (2.0 * S_0 ** 2) * nw
+    Cp_s = 2.0 * Cp_jet
+
+    return {'Cp_d': Cp_d.reshape(shape), 'Cf1_d': Cf1.reshape(shape),
+            'Cf2_d': Cf2.reshape(shape), 'Cq_d': Cq.reshape(shape),
+            'Cp_s': Cp_s.reshape(shape), 'nw': nw.reshape(shape)}
+
+
+def surface_coefficients_plate(s, tau, S_0, alpha_0, eps, R_0, L,
+                               order=DEFAULT_ORDER):
+    '''
+        Convenience wrapper of surface_coefficients over local plate
+        coordinates (s, tau); see plate_point_coords for the mapping.
+    '''
+    s = np.asarray(s, dtype=float)
+    tau = np.asarray(tau, dtype=float)
+    shape = np.broadcast(s, tau).shape
+    sB = np.broadcast_to(s, shape)
+    tB = np.broadcast_to(tau, shape)
+    X, Y, Z = plate_point_coords(sB, tB, alpha_0, L)
+    return surface_coefficients(X, Y, Z, S_0, alpha_0, eps, R_0, order=order)
+
+
+def averaged_coefficients(S_0, alpha_0, eps, R_0, L, W_0, H_0,
+                          n_gl=64, order=DEFAULT_ORDER):
+    '''
+        Plate-averaged properties of Eq. 15 by Gauss-Legendre quadrature
+        over the plate: CP, CF1, CF2, CQ, the moment coefficient
+        CM = 1/(2*H_0*S) * Int tau*Cp,d ds dtau, and s_cc = CM/CP.
+
+        Parameters
+        ----------
+        S_0, alpha_0, eps, R_0, L : as in surface_coefficients
+        W_0 : float
+            plate semi-width along s (m)
+        H_0 : float
+            plate semi-length along the inclined direction tau (m)
+        n_gl : int
+            Gauss-Legendre nodes per plate axis
+        order : int
+            exit-disk quadrature order per axis
+
+        Returns
+        -------
+        dict of float
+            keys 'CP', 'CF1', 'CF2', 'CQ', 'CM', 's_cc'
+    '''
+    nodes, weights = np.polynomial.legendre.leggauss(n_gl)
+    s = W_0 * nodes
+    w_s = W_0 * weights
+    tau = H_0 * nodes
+    w_tau = H_0 * weights
+    Sg, Tg = np.meshgrid(s, tau, indexing='ij')
+    W2D = np.outer(w_s, w_tau)
+    area = 4.0 * W_0 * H_0
+
+    c = surface_coefficients_plate(Sg, Tg, S_0, alpha_0, eps, R_0, L,
+                                   order=order)
+    CP = np.sum(W2D * c['Cp_d']) / area
+    CF1 = np.sum(W2D * c['Cf1_d']) / area
+    CF2 = np.sum(W2D * c['Cf2_d']) / area
+    CQ = np.sum(W2D * c['Cq_d']) / area
+    CM = np.sum(W2D * Tg * c['Cp_d']) / (2.0 * H_0 * area)
+    s_cc = CM / CP if CP != 0.0 else np.nan
+    return {'CP': CP, 'CF1': CF1, 'CF2': CF2, 'CQ': CQ, 'CM': CM,
+            's_cc': s_cc}
+
+
+# ---------------------------------------------------------------------------
+# Section 3: 2D slot jet impinging on an inclined planar plate (Eqs. 1-8)
+# ---------------------------------------------------------------------------
+
+def _scaled_planar_factors(a, S):
+    '''
+        e^(-S^2)-scaled polar-velocity wedge moments e^(a^2) * I_k(a) of a
+        drifting Maxwellian in 2D, k = 1, 2, 3, where
+        I_k(a) = Int_0^inf t^k e^(-(t-a)^2) dt; k = 2 and 3 reproduce the
+        Appendix A_0 and A_1. Here a = S*cos(theta - drift angle) may be
+        NEGATIVE (rays opposed to the drift); a^2 <= S^2 keeps every
+        exponential bounded and (1 + erf(a)) -> 0 kills opposed rays.
+
+        Returns (E1, A0, A1), each pre-multiplied by e^(-S^2).
+    '''
+    erf_term = (1 + erf(a)) * np.exp(a ** 2 - S ** 2)
+    exp_term = np.exp(-S ** 2)
+    sq = np.sqrt(np.pi)
+    E1 = 0.5 * exp_term + 0.5 * sq * a * erf_term
+    A0 = 0.25 * sq * (1 + 2 * a ** 2) * erf_term + 0.5 * a * exp_term
+    A1 = (0.25 * sq * (3 * a + 2 * a ** 3) * erf_term
+          + (0.5 + 0.5 * a ** 2) * exp_term)
+    return E1, A0, A1
+
+
+def _scaled_G_factor(a, S):
+    '''
+        e^(-S^2)-scaled energy-flux integrand of Eq. 4,
+        G(a) = (sqrt(pi)/2)(2 + 7a^2 + 2a^4) e^(a^2) [1 + erf(a)] + 3a + a^3.
+        Verified to equal 2 e^(a^2) (I_4 + I_2/2): the planar c^3 moment
+        plus the out-of-plane w^2 energy carried by the number flux.
+    '''
+    erf_term = (1 + erf(a)) * np.exp(a ** 2 - S ** 2)
+    return (0.5 * np.sqrt(np.pi) * (2 + 7 * a ** 2 + 2 * a ** 4) * erf_term
+            + (3 * a + a ** 3) * np.exp(-S ** 2))
+
+
+def planar_plate_point_coords(s, alpha_0, L):
+    '''2D plate point (X, Y) = (L + s cos(alpha_0), s sin(alpha_0)).'''
+    s = np.asarray(s, dtype=float)
+    return L + s * np.cos(alpha_0), s * np.sin(alpha_0)
+
+
+def planar_surface_coefficients(s, S_0, alpha_0, eps, H, L,
+                                order=DEFAULT_ORDER):
+    '''
+        Exact 2D surface coefficients of Cai 2016 Eqs. 2-4 and 8 at plate
+        positions s (distance from the plate center along the plate).
+
+        The wedge subtended by the slot exit (x = 0, y in [-H, H]) at the
+        plate point (X, Y) spans theta in [atan2(Y - H, X), atan2(Y + H, X)]
+        (Eq. 1); a = S_0 cos(theta). The diffuse-wall density n_w(s) follows
+        from non-penetration with the A_0 number-flux integral,
+        n_w/n_0 = 2/sqrt(pi*eps) * e^(-S_0^2) *
+                  Int A_0(a) sin(alpha_0 - theta) dtheta,
+        the 2D analog of the 3D A_1-integral (module docstring). Front-face
+        visibility clamps sin(alpha_0 - theta) <= 0 contributions, and
+        plate points behind the exit plane (X <= 0) carry zero load.
+
+        Returns dict with 'Cp_d', 'Cf_d', 'Cq_d', 'Cp_s', 'nw'.
+    '''
+    s = np.asarray(s, dtype=float)
+    shape = s.shape
+    X, Y = planar_plate_point_coords(s.ravel(), alpha_0, L)
+    ahead = X > 0.0
+
+    nodes, wts = np.polynomial.legendre.leggauss(order)
+    Xa, Ya = X[ahead][:, None], Y[ahead][:, None]
+    th1 = np.arctan2(Ya - H, Xa)
+    th2 = np.arctan2(Ya + H, Xa)
+    mid, half = 0.5 * (th1 + th2), 0.5 * (th2 - th1)
+    theta = mid + half * nodes[None, :]
+    w = half * wts[None, :]
+
+    a = S_0 * np.cos(theta)
+    _, A0s, A1s = _scaled_planar_factors(a, S_0)
+    Gs = _scaled_G_factor(a, S_0)
+    mu = np.sin(alpha_0 - theta)
+    front = mu > 0.0
+    mu_p = np.where(front, mu, 0.0)
+
+    I_p = np.sum(w * A1s * mu_p ** 2, axis=1)
+    I_f = np.sum(w * A1s * np.sin(2 * alpha_0 - 2 * theta) * front, axis=1)
+    I_q = np.sum(w * Gs * mu_p, axis=1)
+    I_n = np.sum(w * A0s * mu_p, axis=1)
+
+    def expand(vals):
+        full = np.zeros(X.size)
+        full[ahead] = vals
+        return full.reshape(shape)
+
+    nw = expand(2.0 / np.sqrt(np.pi * eps) * I_n)
+    Cp_jet = expand(2.0 / (np.pi * S_0 ** 2) * I_p)
+    Cf_d = expand(1.0 / (np.pi * S_0 ** 2) * I_f)
+    Cq_d = (expand(I_q / (2.0 * np.pi * S_0 ** 3))
+            - eps ** 1.5 * nw / (np.sqrt(np.pi) * S_0 ** 3))
+    return {'Cp_d': Cp_jet + eps / (2.0 * S_0 ** 2) * nw,
+            'Cf_d': Cf_d, 'Cq_d': Cq_d, 'Cp_s': 2.0 * Cp_jet, 'nw': nw}
+
+
+def _mirror_about_plate_2d(p, alpha_0, L):
+    '''Mirror 2D point(s) about the plate line through (L, 0) at alpha_0.'''
+    n_hat = np.array([-np.sin(alpha_0), np.cos(alpha_0)])
+    p = np.asarray(p, dtype=float)
+    d = (p[..., 0] - L) * n_hat[0] + p[..., 1] * n_hat[1]
+    return p - 2.0 * d[..., None] * n_hat
+
+
+def planar_flowfield(X, Y, S_0, alpha_0, eps, H, L, W, plate='diffuse',
+                     order=DEFAULT_ORDER, nw_grid=1024):
+    '''
+        Combined 2D flowfield moments at points (X, Y) for the Section-3
+        problem: the free slot jet plus either the diffuse-plate wall
+        emission (Fig. 5) or the specular virtual nozzle (Fig. 6);
+        plate=None gives the free jet alone (used by the sanity checks).
+
+        Populations are combined by raw moments (number, momentum, energy
+        including the out-of-plane thermal energy at each population's own
+        temperature); T/T0 = (2/3) beta_0^2 (M2/n - V^2) + 0 (the 1/3
+        out-of-plane share is inside M2). Diffuse emission integrates over
+        arrival directions theta with the wall density n_w(s(theta)) at the
+        ray-plate intersection, interpolated from a dense s grid, so finite
+        plate edges are handled naturally (rays missing the plate carry
+        nothing) and only front-face emission counts. The specular virtual
+        exit is the literal mirror of the real exit with mirrored drift
+        (module docstring). No shadowing is modeled (matching the paper's
+        contours); points with X <= 0 return NaN.
+
+        Returns dict 'n' (n/n_0), 'Ux', 'Uy' (times sqrt(beta_0)),
+        'T' (T/T_0).
+    '''
+    X = np.asarray(X, dtype=float)
+    shape = X.shape
+    Xf = X.ravel()
+    Yf = np.asarray(Y, dtype=float).ravel()
+    valid = Xf > 0.0
+    Xa, Ya = Xf[valid][:, None], Yf[valid][:, None]
+
+    nodes, wts = np.polynomial.legendre.leggauss(order)
+    N = np.zeros(Xa.size)
+    MX = np.zeros(Xa.size)
+    MY = np.zeros(Xa.size)
+    M2 = np.zeros(Xa.size)
+
+    def add_population(th_lo, span, drift_angle, S, beta_ratio,
+                       n_ref=None):
+        '''Wedge population moments; n_ref = None means constant n_0.'''
+        nonlocal N, MX, MY, M2
+        theta = th_lo + span * 0.5 * (nodes[None, :] + 1.0)
+        w = span * 0.5 * wts[None, :]
+        a = S * np.cos(theta - drift_angle)
+        E1, A0s, _A1s = _scaled_planar_factors(a, S)
+        dens = 1.0 if n_ref is None else n_ref
+        dN = np.sum(w * dens * E1, axis=1) / np.pi
+        N += dN
+        MX += np.sum(w * dens * A0s * np.cos(theta), axis=1) \
+            / np.pi * beta_ratio
+        MY += np.sum(w * dens * A0s * np.sin(theta), axis=1) \
+            / np.pi * beta_ratio
+        M2 += np.sum(w * dens * _A1s, axis=1) / np.pi * beta_ratio ** 2 \
+            + dN * beta_ratio ** 2 / 2.0
+
+    # free jet: wedge subtended by the slot exit, drift along +x
+    th1 = np.arctan2(Ya - H, Xa)
+    th2 = np.arctan2(Ya + H, Xa)
+    add_population(th1, th2 - th1, 0.0, S_0, 1.0)
+
+    if plate == 'diffuse':
+        s_grid = np.linspace(-W, W, nw_grid)
+        nw_vals = planar_surface_coefficients(s_grid, S_0, alpha_0, eps,
+                                              H, L, order=order)['nw']
+        t_hat = np.array([np.cos(alpha_0), np.sin(alpha_0)])
+        n_hat = np.array([-np.sin(alpha_0), np.cos(alpha_0)])
+        ends = np.array([planar_plate_point_coords(sgn * W, alpha_0, L)
+                         for sgn in (-1.0, 1.0)])
+        ang = np.arctan2(Ya - ends[:, 1], Xa - ends[:, 0])
+        span = np.mod(ang[:, 1:2] - ang[:, 0:1] + np.pi, 2 * np.pi) - np.pi
+        lo = np.where(span >= 0, ang[:, 0:1], ang[:, 1:2])
+        span = np.abs(span)
+        theta = lo + span * 0.5 * (nodes[None, :] + 1.0)
+        w = span * 0.5 * wts[None, :]
+        ct, st = np.cos(theta), np.sin(theta)
+        # ray-plate intersection: P = plate(s) + u * theta_hat, u > 0
+        denom = t_hat[0] * st - t_hat[1] * ct
+        rx, ry = Xa - L, Ya
+        with np.errstate(divide='ignore', invalid='ignore'):
+            s_hit = (rx * st - ry * ct) / denom
+            u_hit = (t_hat[0] * ry - t_hat[1] * rx) / denom
+        emitting = (u_hit > 0.0) & (ct * n_hat[0] + st * n_hat[1] > 0.0)
+        nw_at = np.interp(s_hit, s_grid, nw_vals, left=0.0, right=0.0)
+        nw_at = np.where(emitting & np.isfinite(s_hit), nw_at, 0.0)
+        # resting wall Maxwellian: E1 = 1/2, A0 = sqrt(pi)/4, A1 = 1/2
+        sqe = np.sqrt(eps)
+        dN = np.sum(w * nw_at, axis=1) * 0.5 / np.pi
+        N += dN
+        MX += np.sum(w * nw_at * ct, axis=1) \
+            * (np.sqrt(np.pi) / 4.0) / np.pi * sqe
+        MY += np.sum(w * nw_at * st, axis=1) \
+            * (np.sqrt(np.pi) / 4.0) / np.pi * sqe
+        M2 += np.sum(w * nw_at, axis=1) * 0.5 / np.pi * eps \
+            + dN * eps / 2.0
+    elif plate == 'specular':
+        exit_pts = np.array([[0.0, -H], [0.0, H]])
+        mirrored = _mirror_about_plate_2d(exit_pts, alpha_0, L)
+        ang = np.arctan2(Ya - mirrored[:, 1], Xa - mirrored[:, 0])
+        span = np.mod(ang[:, 1:2] - ang[:, 0:1] + np.pi, 2 * np.pi) - np.pi
+        lo = np.where(span >= 0, ang[:, 0:1], ang[:, 1:2])
+        add_population(lo, np.abs(span), 2.0 * alpha_0, S_0, 1.0)
+    elif plate is not None:
+        raise ValueError(f'unknown plate treatment {plate!r}')
+
+    with np.errstate(divide='ignore', invalid='ignore'):
+        Ux = MX / N
+        Uy = MY / N
+        T = (2.0 / 3.0) * (M2 / N - Ux ** 2 - Uy ** 2)
+
+    def expand(vals):
+        full = np.full(Xf.size, np.nan)
+        full[valid] = vals
+        return full.reshape(shape)
+
+    return {'n': expand(N), 'Ux': expand(Ux), 'Uy': expand(Uy),
+            'T': expand(T)}
+
+
+# ---------------------------------------------------------------------------
+# Section 4 flowfield pressure in the Y = 0 plane (Figs. 15-16)
+# ---------------------------------------------------------------------------
+
+def _plate_emission_moments(Xa, Za, Px, Py, Pz, nw, wA, alpha_0, eps,
+                            chunk=128):
+    '''
+        Raw-moment contributions of the diffuse-wall emission at field
+        points (Xa, 0, Za): solid-angle integrals over plate nodes
+        (Px, Py, Pz) carrying weights wA and wall densities nw, emitting
+        half-space Maxwellians at T_w from the front face only
+        (cos(xi) > 0). Per solid angle: dn = n_w/(4 pi) domega,
+        d(nV) = n_w sqrt(eps)/(2 pi^(3/2)) domega along the ray, and
+        dM2 = 3 n_w eps/(8 pi) domega (the resting-Maxwellian I_2, I_3,
+        I_4 moments; full-sphere limits n_w and 3 n_w R T_w check out).
+
+        Returns (dN, dMx, dMy, dMz, dM2) normalized like the jet moments.
+    '''
+    n_hat = np.array([-np.sin(alpha_0), 0.0, np.cos(alpha_0)])
+    npts = Xa.size
+    dN = np.zeros(npts)
+    dMx = np.zeros(npts)
+    dMy = np.zeros(npts)
+    dMz = np.zeros(npts)
+    dM2 = np.zeros(npts)
+    mom = np.sqrt(eps) / (2.0 * np.pi ** 1.5)
+    for start in range(0, npts, chunk):
+        sl = slice(start, min(start + chunk, npts))
+        dx = Xa[sl][:, None] - Px[None, :]
+        dy = -Py[None, :] * np.ones((Xa[sl].size, 1))
+        dz = Za[sl][:, None] - Pz[None, :]
+        d2 = dx ** 2 + dy ** 2 + dz ** 2
+        d = np.sqrt(d2)
+        cos_xi = (dx * n_hat[0] + dy * n_hat[1] + dz * n_hat[2]) / d
+        cos_xi = np.clip(cos_xi, 0.0, None)   # front-face emission only
+        dodd = nw[None, :] * cos_xi / d2 * wA[None, :]
+        dN[sl] = np.sum(dodd, axis=1) / (4.0 * np.pi)
+        dMx[sl] = mom * np.sum(dodd * dx / d, axis=1)
+        dMy[sl] = mom * np.sum(dodd * dy / d, axis=1)
+        dMz[sl] = mom * np.sum(dodd * dz / d, axis=1)
+        dM2[sl] = 3.0 * eps / (8.0 * np.pi) * np.sum(dodd, axis=1)
+    return dN, dMx, dMy, dMz, dM2
+
+
+def _jet_moments_3d(x_loc, rho_loc, S_0, R_0, order=DEFAULT_ORDER,
+                    chunk=256):
+    '''
+        Raw moments (n/n_0, U*sqrt(beta_0), W*sqrt(beta_0),
+        M2 = n <c^2> beta_0^2 / n_0) of the free round jet at local
+        coordinates (x_loc downstream of the exit, rho_loc off-axis),
+        evaluated with the Cai & Wang 2012 exit-disk integrals via the
+        K/M/N factors imported from RarefiedPlumeGasKinetics (single
+        source of truth). Zero for x_loc <= 0 (no backflow in the model).
+    '''
+    x_loc = np.asarray(x_loc, dtype=float).ravel()
+    rho_loc = np.asarray(rho_loc, dtype=float).ravel()
+
+    nodes, weights = np.polynomial.legendre.leggauss(order)
+    r = 0.5 * R_0 * (nodes + 1)
+    w_r = 0.5 * R_0 * weights
+    epsn = 0.5 * np.pi * nodes
+    w_eps = 0.5 * np.pi * weights
+    Rn, En = np.meshgrid(r, epsn, indexing='ij')
+    W2D = np.outer(w_r, w_eps)
+    sinE = np.sin(En)
+
+    n = np.zeros(x_loc.size)
+    U = np.zeros(x_loc.size)
+    W = np.zeros(x_loc.size)
+    M2 = np.zeros(x_loc.size)
+    idx_all = np.nonzero(x_loc > 0.0)[0]
+    for start in range(0, idx_all.size, chunk):
+        idx = idx_all[start:start + chunk]
+        Xc = x_loc[idx][:, None, None]
+        Zc = rho_loc[idx][:, None, None]
+        Q = get_Q_full(Rn, En, Xc, Zc)
+        Kf = get_K_factor(Q, S_0)
+        Mf = get_M_factor(Q, S_0)
+        Nf = get_N_factor(Q, S_0)
+        I_K = np.sum(W2D * Rn * Kf, axis=(1, 2))
+        I_M = np.sum(W2D * Rn * Mf, axis=(1, 2))
+        I_W = np.sum(W2D * (Zc - Rn * sinE) * Rn * Mf, axis=(1, 2))
+        I_N = np.sum(W2D * Rn * Nf, axis=(1, 2))
+        n[idx] = I_K / (np.pi ** 1.5 * x_loc[idx] ** 2)
+        U[idx] = I_M / I_K
+        W[idx] = I_W / (x_loc[idx] * I_K)
+        T = (-(2.0 / 3.0) * (U[idx] ** 2 + W[idx] ** 2)
+             + (4.0 / 3.0) * I_N / I_K)
+        M2[idx] = n[idx] * (1.5 * T + U[idx] ** 2 + W[idx] ** 2)
+    return n, U, W, M2
+
+
+def flowfield_pressure_plane(X, Z, S_0, alpha_0, eps, R_0, L, W_0, H_0,
+                             plate='diffuse', order=DEFAULT_ORDER,
+                             plate_order=48, chunk=128):
+    '''
+        Static-pressure field p/p_0 = (n/n_0)(T/T_0) in the vertical Y = 0
+        plane for the Section-4 3D impingement problem (Figs. 15-16),
+        normalized by the exit static pressure p_0 = n_0 k T_0. The local
+        temperature enters explicitly (the 2012 paper warns n*k*T_0 is
+        invalid), assembled from the raw moments of the populations:
+
+        * the free round jet (2012 exit-disk integrals, see
+          _jet_moments_3d);
+        * plate='diffuse': the wall re-emission -- a solid-angle integral
+          over the plate of half-space Maxwellians with the Eq.-9 n_w(s,
+          tau) at the plate's own Gauss-Legendre nodes (front-face
+          emission only, cos(xi) > 0);
+        * plate='specular': the virtual nozzle mirrored about the plate
+          plane with mirrored drift (module docstring), evaluated with the
+          same jet integrals in the virtual frame;
+        * plate=None: free jet alone (sanity checks).
+
+        No shadowing is modeled, matching the paper's contour convention;
+        X <= 0 returns NaN.
+
+        Returns dict 'n', 'T', 'p' (all normalized), shaped like X.
+    '''
+    X = np.asarray(X, dtype=float)
+    shape = X.shape
+    Xf = X.ravel()
+    Zf = np.asarray(Z, dtype=float).ravel()
+    valid = Xf > 0.0
+    Xa, Za = Xf[valid], Zf[valid]
+    npts = Xa.size
+
+    # free jet in the global frame (axis +x, exit at the origin)
+    n1, U1, W1, M21 = _jet_moments_3d(Xa, np.abs(Za), S_0, R_0, order=order)
+    N = n1.copy()
+    MXv = n1 * U1
+    MYv = np.zeros(npts)
+    MZv = n1 * W1 * np.sign(Za)
+    M2 = M21.copy()
+
+    if plate == 'diffuse':
+        nodes, wts = np.polynomial.legendre.leggauss(plate_order)
+        s_n = W_0 * nodes
+        w_s = W_0 * wts
+        t_n = H_0 * nodes
+        w_t = H_0 * wts
+        Sg, Tg = np.meshgrid(s_n, t_n, indexing='ij')
+        wA = np.outer(w_s, w_t).ravel()
+        Px, Py, Pz = plate_point_coords(Sg.ravel(), Tg.ravel(), alpha_0, L)
+        nw = surface_coefficients(Px, Py, Pz, S_0, alpha_0, eps, R_0,
+                                  order=order)['nw']
+        dN, dMx, dMy, dMz, dM2 = _plate_emission_moments(
+            Xa, Za, Px, Py, Pz, nw, wA, alpha_0, eps, chunk=chunk)
+        N += dN
+        MXv += dMx
+        MYv += dMy
+        MZv += dMz
+        M2 += dM2
+    elif plate == 'specular':
+        origin_v = np.array([L * (1.0 - np.cos(2 * alpha_0)), 0.0,
+                             -L * np.sin(2 * alpha_0)])
+        axis_v = np.array([np.cos(2 * alpha_0), 0.0, np.sin(2 * alpha_0)])
+        rx = Xa - origin_v[0]
+        rz = Za - origin_v[2]
+        x_loc = rx * axis_v[0] + rz * axis_v[2]
+        px = rx - x_loc * axis_v[0]
+        pz = rz - x_loc * axis_v[2]
+        rho = np.hypot(px, pz)
+        n2, U2, W2, M22 = _jet_moments_3d(x_loc, rho, S_0, R_0, order=order)
+        safe = rho > 1e-12
+        rhx = np.where(safe, px / np.where(safe, rho, 1.0), 0.0)
+        rhz = np.where(safe, pz / np.where(safe, rho, 1.0), 0.0)
+        N += n2
+        MXv += n2 * (U2 * axis_v[0] + W2 * rhx)
+        MZv += n2 * (U2 * axis_v[2] + W2 * rhz)
+        M2 += M22
+    elif plate is not None:
+        raise ValueError(f'unknown plate treatment {plate!r}')
+
+    with np.errstate(divide='ignore', invalid='ignore'):
+        Vx = MXv / N
+        Vy = MYv / N
+        Vz = MZv / N
+        T = (2.0 / 3.0) * (M2 / N - Vx ** 2 - Vy ** 2 - Vz ** 2)
+        p = N * T
+
+    def expand(vals):
+        full = np.full(Xf.size, np.nan)
+        full[valid] = vals
+        return full.reshape(shape)
+
+    return {'n': expand(N), 'T': expand(T), 'p': expand(p)}
+
+
+def run_sanity_checks(S_0=2.0, alpha_0=np.deg2rad(60.0), eps=1.5,
+                      R_0=0.5, L=4.0, verbose=True):
+    '''
+        Built-in verification of the implementation:
+
+        1. s-symmetry: Cp_d, Cf1_d, Cq_d even in s; Cf2_d odd in s
+           (Figs. 17-21 are left-right symmetric / antisymmetric).
+        2. Cp_s = 2 x jet-only part of Cp_d (Eq. 14 vs Eq. 9), i.e.
+           Cp_s = 2*(Cp_d - eps/(2*S_0^2)*n_w/n_0).
+        3. Wall-term flux balance: the incoming number-flux integral
+           recomputed independently with scipy.integrate.dblquad matches
+           the Gauss-Legendre n_w to ~1e-10 (validates both the quadrature
+           and the n_w reduction).
+        4. Quadrature convergence: order 48 vs 96 agree to ~1e-12.
+
+        Raises AssertionError on failure; returns a dict of the measured
+        deviations.
+    '''
+    from scipy import integrate
+
+    s = np.linspace(-3.5, 3.5, 15)
+    tau = np.linspace(-3.5, 3.5, 15)
+    Sg, Tg = np.meshgrid(s, tau, indexing='ij')
+    c = surface_coefficients_plate(Sg, Tg, S_0, alpha_0, eps, R_0, L)
+    c_mirror = surface_coefficients_plate(-Sg, Tg, S_0, alpha_0, eps, R_0, L)
+
+    results = {}
+    for key, parity in [('Cp_d', 1), ('Cf1_d', 1), ('Cq_d', 1),
+                        ('Cf2_d', -1)]:
+        dev = np.max(np.abs(c[key] - parity * c_mirror[key]))
+        scale = np.max(np.abs(c[key]))
+        results[f'symmetry_{key}'] = dev / scale
+        assert dev <= 1e-12 * scale, f'{key} s-parity violated: {dev}'
+
+    dev = np.max(np.abs(
+        c['Cp_s'] - 2.0 * (c['Cp_d'] - eps / (2 * S_0 ** 2) * c['nw'])))
+    results['specular_vs_jet'] = dev
+    assert dev <= 1e-14, f'Cp_s != 2 x jet-only Cp_d: {dev}'
+
+    # independent dblquad check of the n_w flux integral at spot points
+    sin_a, cos_a = np.sin(alpha_0), np.cos(alpha_0)
+    for s0, t0 in [(0.0, 0.0), (1.5, -2.0), (-2.5, 3.0)]:
+        X, Y, Z = plate_point_coords(s0, t0, alpha_0, L)
+        X, Y, Z = float(X), float(Y), float(Z)
+
+        def flux_integrand(r, th):
+            dy = Y - r * np.cos(th)
+            dz = Z - r * np.sin(th)
+            Q = np.sqrt((X ** 2 + dy ** 2 + dz ** 2) / X ** 2)
+            a = S_0 / Q
+            A1, _, _ = _scaled_A_factors(np.asarray(a), S_0)
+            mu = sin_a - (dz / X) * cos_a
+            return float(A1) / Q ** 4 * max(mu, 0.0) * r
+
+        I_n_ref, _ = integrate.dblquad(
+            flux_integrand, 0.0, 2 * np.pi, 0.0, R_0,
+            epsabs=1e-13, epsrel=1e-12)
+        nw_ref = (2.0 / np.sqrt(eps)) * I_n_ref / (np.pi * X ** 2)
+        nw_gl = float(surface_coefficients(
+            np.array([X]), np.array([Y]), np.array([Z]),
+            S_0, alpha_0, eps, R_0)['nw'][0])
+        dev = abs(nw_gl - nw_ref) / nw_ref
+        results[f'nw_dblquad_s{s0}_tau{t0}'] = dev
+        assert dev <= 1e-9, f'n_w flux balance failed at ({s0},{t0}): {dev}'
+
+    c_fine = surface_coefficients_plate(Sg, Tg, S_0, alpha_0, eps, R_0, L,
+                                        order=2 * DEFAULT_ORDER)
+    for key in ('Cp_d', 'Cf1_d', 'Cf2_d', 'Cq_d'):
+        scale = np.max(np.abs(c_fine[key]))
+        dev = np.max(np.abs(c[key] - c_fine[key])) / scale
+        results[f'convergence_{key}'] = dev
+        assert dev <= 1e-10, f'quadrature not converged for {key}: {dev}'
+
+    if verbose:
+        for name, value in results.items():
+            print(f'  {name}: {value:.3e}')
+    return results
+
+
+def run_planar_sanity_checks(S_0=2.0, alpha_0=np.deg2rad(60.0), eps=1.5,
+                             H=0.5, L=4.0, W=5.0, verbose=True):
+    '''
+        Verification of the Section-3 (2D planar) implementation:
+
+        1. alpha_0 = 90 deg parity: Cp,d/Cq,d/n_w even and Cf,d odd in s
+           (the normal-plate configuration is mirror-symmetric).
+        2. Cp,s = 2 x jet-only part of Cp,d (Eq. 8 vs Eq. 2).
+        3. n_w flux balance against an independent scipy.integrate.quad
+           evaluation of the A_0 number-flux integral.
+        4. Diffuse half-space closure: just in front of the plate center
+           the wall-emission population fills a half-space, so its density
+           tends to n_w(0)/2 (checked via flowfield(diffuse) - flowfield
+           (jet only)).
+        5. Specular mirror symmetry: the virtual-nozzle field satisfies
+           T(P) = T(P') and n(P) = n(P') for P' mirrored about the plate
+           line -- the defining symmetry of Fig. 6.
+
+        Raises AssertionError on failure; returns measured deviations.
+    '''
+    from scipy import integrate
+
+    results = {}
+    s = np.linspace(-4.0, 4.0, 17)
+    c90 = planar_surface_coefficients(s, S_0, np.pi / 2, eps, H, L)
+    for key, parity in [('Cp_d', 1), ('Cq_d', 1), ('nw', 1), ('Cf_d', -1)]:
+        dev = np.max(np.abs(c90[key] - parity * c90[key][::-1]))
+        scale = np.max(np.abs(c90[key]))
+        results[f'planar_parity_{key}'] = dev / scale
+        assert dev <= 1e-12 * scale, f'2D {key} parity violated: {dev}'
+
+    c = planar_surface_coefficients(s, S_0, alpha_0, eps, H, L)
+    dev = np.max(np.abs(
+        c['Cp_s'] - 2.0 * (c['Cp_d'] - eps / (2 * S_0 ** 2) * c['nw'])))
+    results['planar_specular_vs_jet'] = dev
+    assert dev <= 1e-14, f'2D Cp_s != 2 x jet-only Cp_d: {dev}'
+
+    for s0 in (0.0, -2.0, 3.0):
+        X, Y = planar_plate_point_coords(s0, alpha_0, L)
+
+        def flux_integrand(theta):
+            a = S_0 * np.cos(theta)
+            _, A0s, _ = _scaled_planar_factors(np.asarray(a), S_0)
+            return float(A0s) * max(np.sin(alpha_0 - theta), 0.0)
+
+        I_ref, _ = integrate.quad(flux_integrand,
+                                  np.arctan2(Y - H, X),
+                                  np.arctan2(Y + H, X),
+                                  epsabs=1e-13, epsrel=1e-12)
+        nw_ref = 2.0 / np.sqrt(np.pi * eps) * I_ref
+        nw_gl = float(planar_surface_coefficients(
+            np.array([s0]), S_0, alpha_0, eps, H, L)['nw'][0])
+        dev = abs(nw_gl - nw_ref) / nw_ref
+        results[f'planar_nw_quad_s{s0}'] = dev
+        assert dev <= 1e-9, f'2D n_w flux balance failed at s={s0}: {dev}'
+
+    h = 1e-3
+    n_hat = np.array([-np.sin(alpha_0), np.cos(alpha_0)])
+    P = np.array([L, 0.0]) + h * n_hat
+    both = planar_flowfield(P[0:1], P[1:2], S_0, alpha_0, eps, H, L, W,
+                            plate='diffuse')
+    jet = planar_flowfield(P[0:1], P[1:2], S_0, alpha_0, eps, H, L, W,
+                           plate=None)
+    nw0 = float(planar_surface_coefficients(
+        np.array([0.0]), S_0, alpha_0, eps, H, L)['nw'][0])
+    emission = float(both['n'][0] - jet['n'][0])
+    dev = abs(emission - nw0 / 2.0) / (nw0 / 2.0)
+    results['planar_halfspace_closure'] = dev
+    assert dev <= 1e-2, f'2D wall-emission half-space closure: {dev}'
+
+    pts = np.array([[1.0, 0.5], [2.5, -1.0], [3.0, 2.0], [1.5, -2.5]])
+    mirrored = _mirror_about_plate_2d(pts, alpha_0, L)
+    f1 = planar_flowfield(pts[:, 0], pts[:, 1], S_0, alpha_0, eps, H, L,
+                          W, plate='specular')
+    f2 = planar_flowfield(mirrored[:, 0], mirrored[:, 1], S_0, alpha_0,
+                          eps, H, L, W, plate='specular')
+    for key in ('n', 'T'):
+        dev = np.max(np.abs(f1[key] - f2[key]) / np.abs(f1[key]))
+        results[f'planar_specular_mirror_{key}'] = dev
+        assert dev <= 1e-9, f'2D specular mirror symmetry ({key}): {dev}'
+
+    if verbose:
+        for name, value in results.items():
+            print(f'  {name}: {value:.3e}')
+    return results
+
+
+def run_flowfield3d_sanity_checks(S_0=2.0, alpha_0=np.deg2rad(60.0),
+                                  eps=1.5, R_0=0.5, L=4.0, W_0=4.0,
+                                  H_0=4.0, verbose=True):
+    '''
+        Verification of the Section-4 flowfield-pressure implementation
+        (Figs. 15-16):
+
+        1. Solid-angle sum rule for the wall-emission kernel: a uniformly
+           emitting square plate (half-side a, on-axis height h) subtends
+           the closed-form solid angle 4*atan(a^2/(h*sqrt(2a^2 + h^2))),
+           so the emission density must equal n_w * Omega/(4 pi) exactly
+           (-> n_w/2 in the half-space limit). Validates the kernel
+           constant and geometry independent of n_w.
+        2. GL-vs-dblquad of the real n_w-weighted emission-density
+           integral at a field point (validates the assembly with the
+           Eq.-9 wall density).
+        3. Specular mirror symmetry in the Y = 0 plane: n, T, p match at
+           points mirrored about the plate line (the virtual-nozzle
+           construction's defining property).
+
+        Raises AssertionError on failure; returns measured deviations.
+    '''
+    from scipy import integrate
+
+    results = {}
+    kw = dict(S_0=S_0, alpha_0=alpha_0, eps=eps, R_0=R_0, L=L,
+              W_0=W_0, H_0=H_0)
+
+    # 1. uniform-emitter sum rule (synthetic plate, alpha_0 = 90 deg so
+    # the plate normal is -x and "on-axis height" is along x)
+    a_test, h_test, n_gl = 40.0, 5.0, 96
+    nodes, wts = np.polynomial.legendre.leggauss(n_gl)
+    Sg, Tg = np.meshgrid(a_test * nodes, a_test * nodes, indexing='ij')
+    wA = np.outer(a_test * wts, a_test * wts).ravel()
+    Px, Py, Pz = plate_point_coords(Sg.ravel(), Tg.ravel(), np.pi / 2, 0.0)
+    dN, _, _, _, _ = _plate_emission_moments(
+        np.array([-h_test]), np.array([0.0]), Px, Py, Pz,
+        np.ones(Px.size), wA, np.pi / 2, eps)
+    omega = 4.0 * np.arctan(a_test ** 2 / (
+        h_test * np.sqrt(2 * a_test ** 2 + h_test ** 2)))
+    dev = abs(float(dN[0]) - omega / (4 * np.pi)) / (omega / (4 * np.pi))
+    results['3d_solid_angle_sum_rule'] = dev
+    assert dev <= 1e-6, f'3D emission solid-angle sum rule: {dev}'
+
+    # 2. GL vs dblquad with the real Eq.-9 n_w at a resolvable standoff
+    n_hat2 = np.array([-np.sin(alpha_0), np.cos(alpha_0)])
+    P = np.array([L, 0.0]) + 1.0 * n_hat2 + np.array([0.3, 0.0])
+    both = flowfield_pressure_plane(P[0:1], P[1:2], plate='diffuse', **kw)
+    jet = flowfield_pressure_plane(P[0:1], P[1:2], plate=None, **kw)
+    emission_gl = float(both['n'][0] - jet['n'][0])
+    n_hat3 = np.array([-np.sin(alpha_0), 0.0, np.cos(alpha_0)])
+
+    def integrand(tau, s):
+        px, py, pz = plate_point_coords(s, tau, alpha_0, L)
+        nw = float(surface_coefficients(
+            np.array([px]), np.array([py]), np.array([pz]),
+            S_0, alpha_0, eps, R_0)['nw'][0])
+        dvec = np.array([P[0] - px, -py, P[1] - pz])
+        d2 = float(dvec @ dvec)
+        cos_xi = max(float(dvec @ n_hat3) / np.sqrt(d2), 0.0)
+        return nw * cos_xi / d2 / (4.0 * np.pi)
+
+    emission_ref, _ = integrate.dblquad(integrand, -W_0, W_0, -H_0, H_0,
+                                        epsabs=1e-10, epsrel=1e-8)
+    dev = abs(emission_gl - emission_ref) / emission_ref
+    results['3d_emission_gl_vs_dblquad'] = dev
+    assert dev <= 1e-6, f'3D emission GL vs dblquad: {dev}'
+
+    pts = np.array([[1.0, 0.5], [2.5, -1.0], [3.0, 2.0], [1.5, -2.5]])
+    mirrored = _mirror_about_plate_2d(pts, alpha_0, L)
+    f1 = flowfield_pressure_plane(pts[:, 0], pts[:, 1],
+                                  plate='specular', **kw)
+    f2 = flowfield_pressure_plane(mirrored[:, 0], mirrored[:, 1],
+                                  plate='specular', **kw)
+    for key in ('n', 'T', 'p'):
+        dev = np.max(np.abs(f1[key] - f2[key]) / np.abs(f1[key]))
+        results[f'3d_specular_mirror_{key}'] = dev
+        assert dev <= 1e-9, f'3D specular mirror symmetry ({key}): {dev}'
+
+    if verbose:
+        for name, value in results.items():
+            print(f'  {name}: {value:.3e}')
+    return results
+
+
+if __name__ == '__main__':
+    print('Cai 2016 reference implementation sanity checks '
+          '(S0=2, alpha0=60 deg, eps=1.5, L=4D):')
+    run_sanity_checks()
+    print('Section-3 (2D planar) checks:')
+    run_planar_sanity_checks()
+    print('Section-4 flowfield-pressure checks:')
+    run_flowfield3d_sanity_checks()
+    print('all checks passed')
+    avg = averaged_coefficients(2.0, np.deg2rad(60.0), 1.5, 0.5, 4.0,
+                                4.0, 4.0)
+    print('Eq. 15 averaged coefficients at the paper conditions:')
+    for key, value in avg.items():
+        print(f'  {key} = {value:.6g}')
+
+    # paper-figure anchors (visual validation targets)
+    s = np.linspace(-5.0, 5.0, 401)
+    c2d = planar_surface_coefficients(s, 2.0, np.deg2rad(60.0), 1.5,
+                                      0.5, 4.0)
+    print('2D anchors (S0=2, 60 deg): '
+          f"peak Cp_d {c2d['Cp_d'].max():.3f} (Fig. 7 ~0.93), "
+          f"peak Cp_s {c2d['Cp_s'].max():.3f} (Fig. 8 ~1.23), "
+          f"peak Cf_d {c2d['Cf_d'].max():.3f} (Fig. 9 ~0.33), "
+          f"peak Cq_d {c2d['Cq_d'].max():.3f} (Fig. 10 ~0.27)")
+    sign_change = s[np.nonzero(np.diff(np.sign(c2d['Cf_d'])))[0]]
+    print(f'  Cf_d zero crossings at s/(2H) = {np.round(sign_change, 2)} '
+          '(Fig. 9 separation point ~ -2)')
+    x = np.linspace(0.2, 7.0, 60)
+    y = np.linspace(-3.5, 3.5, 50)
+    Xg, Yg = np.meshgrid(x, y)
+    Td = planar_flowfield(Xg, Yg, 2.0, np.deg2rad(60.0), 1.5, 0.5, 4.0,
+                          5.0, plate='diffuse')['T']
+    Ts = planar_flowfield(Xg, Yg, 2.0, np.deg2rad(60.0), 1.5, 0.5, 4.0,
+                          5.0, plate='specular')['T']
+    print(f'2D flowfield peaks: diffuse T/T0 {np.nanmax(Td):.2f} '
+          f'(Fig. 5 top contour 2.4), specular {np.nanmax(Ts):.2f} '
+          '(Fig. 6 top contour 3.5)')
+    pd = flowfield_pressure_plane(Xg, Yg, 2.0, np.deg2rad(60.0), 1.5,
+                                  0.5, 4.0, 4.0, 4.0, plate='diffuse')['p']
+    ps = flowfield_pressure_plane(Xg, Yg, 2.0, np.deg2rad(60.0), 1.5,
+                                  0.5, 4.0, 4.0, 4.0,
+                                  plate='specular')['p']
+    # near the exit p/p0 -> 1 for any plate; the figure anchor is the
+    # impingement-center accumulation region (X > 2.5)
+    imp = Xg > 2.5
+    print('3D flowfield impingement-region peaks: diffuse p/p0 '
+          f'{np.nanmax(pd[imp]):.2f} (Fig. 15 top contour 0.5), specular '
+          f'{np.nanmax(ps[imp]):.2f} (Fig. 16 top contour 0.4)')
diff --git a/pyrpod/plume/PlumeStrikeCalculator.py b/pyrpod/plume/PlumeStrikeCalculator.py
index 755f8c9..4ac9463 100644
--- a/pyrpod/plume/PlumeStrikeCalculator.py
+++ b/pyrpod/plume/PlumeStrikeCalculator.py
@@ -11,9 +11,19 @@
 Implementation notes:
 - compute_plume_strikes() runs a NumPy-vectorized strike-detection path by
   default. _compute_plume_strikes_scalar() preserves the original per-face
-  loop verbatim as a reference implementation for tests and benchmarking.
+  loop as a reference implementation for tests and benchmarking; the two
+  must produce identical strike arrays, struck-face IDs, and load values.
 - The vectorized core operates on plain serializable inputs (arrays, dicts,
   floats) so it can also run inside process-based workers.
+- Surface loads use the TRUE incidence angle: the positional off-axis angle
+  theta locates a face in the plume field (SimplifiedGasKinetics evaluates
+  n, U, T there, and the legacy 3.14-based theta still gates the wedge hit
+  test, bit-for-bit unchanged), but the Shen/Maxwellian wall formulas
+  receive the angle between the local flow direction (face centroid minus
+  thruster exit -- the collisionless flow is radial) and the face unit
+  normal. Previously the positional theta was fed to the wall formulas as
+  the incidence angle, so plate orientation never affected load magnitudes;
+  _surface_loads_with_incidence() is the shared fix for both paths.
 
 Future work (no new dependencies planned):
 - Vectorize the SimplifiedGasKinetics evaluations for struck faces.
@@ -26,7 +36,53 @@
 from typing import Any, Dict, List, Optional, Sequence
 
 import numpy as np
-from pyrpod.plume.RarefiedPlumeGasKinetics import SimplifiedGasKinetics
+from pyrpod.plume.RarefiedPlumeGasKinetics import (
+    AVOGADROS_NUMBER,
+    SimplifiedGasKinetics,
+    get_maxwellian_heat_transfer,
+    get_maxwellian_pressure,
+    get_maxwellian_shear_pressure,
+)
+
+
+def _surface_loads_with_incidence(simple_plume: SimplifiedGasKinetics,
+                                  incidence: float):
+    """Maxwellian surface loads for a struck face at the true incidence angle.
+
+    simple_plume carries the plume-field state at the face's position (its
+    constructor theta is the positional off-axis angle -- a plume-field
+    coordinate); this helper extracts the same local field values the class's
+    own get_pressure/get_shear_pressure/get_heat_flux use (including their
+    exact-centerline branch at theta == 0) and feeds them to the Shen wall
+    formulas with `incidence`, the angle between the local flow direction
+    (radial from the thruster exit) and the face unit normal.
+
+    Returns (pressure, shear, heat_flux) in SI units; shear is signed as
+    returned by get_maxwellian_shear_pressure (callers take abs, matching
+    the legacy accumulation).
+    """
+    if simple_plume.theta != 0:  # not on plume centerline
+        n_inf = simple_plume.n_0 * simple_plume.get_num_density_ratio()
+        T = simple_plume.T_0 * simple_plume.get_temp_ratio()
+        u = simple_plume.get_U_normalized() / simple_plume.beta_0
+        w = simple_plume.get_W_normalized() / simple_plume.beta_0
+        U = np.sqrt(u ** 2 + w ** 2)
+    else:  # on plume centerline: exact closed forms
+        n_inf = simple_plume.n_0 * simple_plume.get_num_density_centerline()
+        T = simple_plume.T_0 * simple_plume.get_temp_centerline()
+        U = simple_plume.get_velocity_centerline() / simple_plume.beta_0
+    rho_inf = n_inf * simple_plume.molar_mass / AVOGADROS_NUMBER
+    S = U * simple_plume.get_beta(T)
+
+    sigma = simple_plume.sigma
+    T_w = simple_plume.T_w
+    pressure = get_maxwellian_pressure(rho_inf, U, S, sigma, incidence,
+                                       T, T_w)
+    shear = get_maxwellian_shear_pressure(rho_inf, U, S, sigma, incidence)
+    heat_flux = get_maxwellian_heat_transfer(rho_inf, S, sigma, incidence,
+                                             T, T_w, simple_plume.R,
+                                             simple_plume.gamma)
+    return pressure, shear, heat_flux
 
 
 def compute_face_centroids(vectors: np.ndarray) -> np.ndarray:
@@ -159,14 +215,19 @@ def _compute_plume_strikes_core(
             sigma = plume_params['sigma']
             t_type = thruster_data[thruster_id]['type'][0]
             metrics = thruster_metrics[t_type]
+            # True incidence angle between the local (radial) flow direction
+            # -unit_distance and the face unit normal; fed to the wall
+            # formulas in place of the positional theta (see module header).
+            incidence = np.arccos(np.clip(
+                (unit_distance * normals).sum(axis=1), -1.0, 1.0))
             for idx in np.nonzero(hit)[0]:
                 simple_plume = SimplifiedGasKinetics(
                     norm_distance[idx], theta[idx], metrics, T_w, sigma
                 )
-                pressures[idx] += simple_plume.get_pressure()
-                shear = simple_plume.get_shear_pressure()
+                p, shear, hf = _surface_loads_with_incidence(
+                    simple_plume, incidence[idx])
+                pressures[idx] += p
                 shear_stresses[idx] += abs(shear)
-                hf = simple_plume.get_heat_flux()
                 heat_flux[idx] += hf
                 heat_flux_load[idx] += hf * firing_time
 
@@ -229,9 +290,12 @@ def _compute_plume_strikes_scalar(
 ) -> Dict[str, np.ndarray]:
     """Scalar reference implementation of compute_plume_strikes().
 
-    Preserved verbatim from the original per-face loop. Kept for regression
-    tests, debugging, and benchmarking against the vectorized path; the two
-    must produce identical strike arrays and struck-face IDs.
+    Preserves the original per-face loop structure (the hit test is
+    bit-for-bit the legacy computation). Kept for regression tests,
+    debugging, and benchmarking against the vectorized path; the two must
+    produce identical strike arrays, struck-face IDs, and load values.
+    Surface loads use the true incidence angle via the shared
+    _surface_loads_with_incidence(), exactly as the vectorized core does.
     """
     num_faces = len(target_mesh.vectors)
     strikes = np.zeros(num_faces)
@@ -298,10 +362,14 @@ def _compute_plume_strikes_scalar(
                     t_type = vv.thruster_data[thruster_id]['type'][0]
                     thruster_metrics = vv.thruster_metrics[t_type]
                     simple_plume = SimplifiedGasKinetics(norm_distance, theta, thruster_metrics, T_w, sigma)
-                    pressures[idx] += simple_plume.get_pressure()
-                    shear = simple_plume.get_shear_pressure()
+                    # True incidence angle (see module header): local flow
+                    # direction -unit_distance vs the face unit normal.
+                    incidence = np.arccos(np.clip(
+                        np.dot(np.squeeze(unit_distance), n), -1.0, 1.0))
+                    p, shear, hf = _surface_loads_with_incidence(
+                        simple_plume, incidence)
+                    pressures[idx] += p
                     shear_stresses[idx] += abs(shear)
-                    hf = simple_plume.get_heat_flux()
                     heat_flux[idx] += hf
                     heat_flux_load[idx] += hf * firing_time
 
diff --git a/scripts/inclined_plate_sweep_study.py b/scripts/inclined_plate_sweep_study.py
new file mode 100644
index 0000000..f27a9f4
--- /dev/null
+++ b/scripts/inclined_plate_sweep_study.py
@@ -0,0 +1,414 @@
+"""Phase-3 driver: angle x distance sweep of the Cai 2016 inclined plate.
+
+Runs the 95-firing sweep JFH of case/plume/plume_inclined_plate_sweep
+(generated by that case's jfh/generate_sweep_jfh.py: VV on arcs of radius L
+about the stationary plate center, thruster aimed at the center; alpha = 0 is
+head-on = paper
+alpha0 = 90 deg, alpha_paper = 90 - |alpha| deg; L/D in {2, 4, 6, 8, 10})
+through the strike pipeline's per-firing core, compute_plume_strikes -- the
+same function PlumeStrikeEstimationStudy calls per firing -- keeping each
+firing's per-face arrays separate so the pipeline's cumulative accumulation
+never pollutes the per-pose analysis. This is a standalone study script:
+nothing in pyrpod/mdao is used and nothing is optimized.
+
+Outputs, under case/plume/plume_inclined_plate_sweep/results/ (gitignored):
+  - sweep/sweep_coefficients.csv: per firing, the Eq.-15 plate-averaged
+    coefficients CP/CF1/CF2/CQ/CM/s_cc from the pipeline AND from the exact
+    reference (pyrpod/plume/CaiImpingement2016.py), plus the peak per-face
+    Cp / |Cf| / Cq, struck-face counts, and per-firing wall time;
+  - sweep/coeff_<name>.png: each averaged coefficient vs alpha, one curve
+    per L/D, pipeline (solid + markers) and reference (dashed) together;
+  - sweep/peaks.png: peak per-face pressure/shear/heat-flux coefficients vs
+    alpha per L/D;
+  - strikes/firing-<i>.vtu: one VTK unstructured grid per firing, numbered
+    strictly by JFH index (the standard RPOD strike convention; same writer
+    as the other RPOD cases) carrying that pose's own per-face strikes,
+    dimensional loads (pressure_Pa, shear_Pa, heat_flux_W_m2), and
+    coefficients (Cp, Cshear, Cf1_case, Cf2_case, Cq). The Cf components
+    here are in the mesh's CASE frame, un-flipped -- so the shear vectors
+    point the way they physically do on that pose's mesh, unlike the
+    paper-convention aggregate CF1/CM in the CSV. Written per firing
+    (independent poses; no cumulative accumulation, unlike
+    PlumeStrikeEstimationStudy.jfh_plume_strikes), so each file is exactly
+    one pose. strikes/sweep_LoD<LD>.pvd ParaView collections group the
+    fixed-distance poses with alpha as the time coordinate, so an angle
+    sweep can be scrubbed in ParaView. Disable the VTK export with
+    --no-vtk (CSV + plots only).
+
+Conventions and sanity checks:
+  - Averaged pipeline coefficients follow Eq. 15: area-weighted sums over
+    the whole plate area S (unstruck faces carry zero load), with
+    CM = sum(tau * Cp * A) / (2 * H0 * S) and s_cc = CM / CP.
+  - The pipeline's per-face |shear| is decomposed onto the plate's
+    (tau, s) axes along the tangential projection of the radial flow
+    direction (the same decomposition as the Phase-1 figure overlays) to
+    obtain signed Cf1/Cf2 comparable to the paper's components.
+  - Poses with alpha < 0 map directly onto the paper geometry
+    (tau_paper = tau_case); alpha > 0 is its mirror image, so CF1 and CM
+    are sign-flipped into the paper convention. Mirror symmetry of the
+    results in +/-alpha is then asserted (the plate is square).
+  - +/-90 deg is edge-on/degenerate: the firings are kept (CSV rows and a
+    printed report) but excluded from the plots and the mirror check. At
+    exactly edge-on the facing test's surface_dot_plume is 0 in exact
+    arithmetic, so the mesh's float32 normals make strike membership
+    epsilon-arbitrary (a third to two thirds of the faces pass, not
+    mirror-symmetrically). The plate-AVERAGED load there is ~zero as
+    expected (a few percent of head-on), but individual epsilon-passing
+    faces next to the in-plane nozzle carry large grazing near-field
+    values at close range (peak Cp ~ 4 at L/D = 2), which would dominate
+    the peak plots meaninglessly. (The reference at alpha_paper = 0
+    likewise keeps only the small plume-spread load.)
+
+Run from the repo root:  python scripts/inclined_plate_sweep_study.py
+(add --no-vtk to skip the per-pose VTK export).
+"""
+
+import argparse
+import csv
+import sys
+import time
+from pathlib import Path
+
+import numpy as np
+
+_REPO_ROOT = Path(__file__).resolve().parents[1]
+for extra in (_REPO_ROOT, _REPO_ROOT / 'tests' / 'plume'):
+    if str(extra) not in sys.path:
+        sys.path.insert(0, str(extra))
+
+import matplotlib  # noqa: E402
+matplotlib.use('Agg')
+import matplotlib.pyplot as plt  # noqa: E402
+
+import plume_impingement_utils as piu  # noqa: E402  (paper constants)
+from pyrpod.mission import MissionEnvironment  # noqa: E402
+from pyrpod.plume import CaiImpingement2016 as cai  # noqa: E402
+from pyrpod.plume.PlumeStrikeCalculator import (  # noqa: E402
+    compute_face_centroids,
+    compute_plume_strikes,
+)
+from pyrpod.rpod import JetFiringHistory  # noqa: E402
+from pyrpod.util.stl.stl import convert_stl_to_vtk  # noqa: E402
+from pyrpod.vehicle import TargetVehicle, VisitingVehicle  # noqa: E402
+
+CASE_DIR = str(_REPO_ROOT / 'case' / 'plume' / 'plume_inclined_plate_sweep') + '/'
+SWEEP_JFH = 'jfh_inclined_plate_sweep.A'
+RESULTS_DIR = Path(CASE_DIR) / 'results' / 'sweep'
+# Per-pose strikes follow the standard RPOD convention: one .vtu per firing,
+# numbered by JFH index in results/strikes/ (firing-<i>.vtu). The CSV and the
+# coefficient/peak plots stay in results/sweep/.
+STRIKES_DIR = Path(CASE_DIR) / 'results' / 'strikes'
+
+PLATE_CENTER = np.array([4.0, 0.0, 0.0])
+ALPHA0_DEG = 60.0                       # the mesh's fixed global tilt
+H_0 = W_0 = 4.0                         # plate semi-lengths (m)
+ALPHAS_DEG = np.arange(-90.0, 90.0 + 1e-9, 10.0)
+L_OVER_D = [2.0, 4.0, 6.0, 8.0, 10.0]
+
+# dataviz categorical palette, fixed slot order (validated CVD-safe)
+PALETTE = ['#2a78d6', '#008300', '#e87ba4', '#eda100', '#1baf7a']
+
+_A0 = np.deg2rad(ALPHA0_DEG)
+NORMAL_OUT = np.array([-np.sin(_A0), 0.0, np.cos(_A0)])  # toward the VV side
+TANGENT_TAU = np.array([np.cos(_A0), 0.0, np.sin(_A0)])
+TANGENT_S = np.array([0.0, 1.0, 0.0])
+
+COEFF_NAMES = ['CP', 'CF1', 'CF2', 'CQ', 'CM', 's_cc']
+
+
+def load_case():
+    jfh = JetFiringHistory.JetFiringHistory(CASE_DIR)
+    jfh.config.set('jfh', 'jfh', SWEEP_JFH)  # sweep JFH, same case assets
+    jfh.read_jfh()
+
+    tv = TargetVehicle.TargetVehicle(CASE_DIR)
+    tv.set_stl()
+
+    vv = VisitingVehicle.VisitingVehicle(CASE_DIR)
+    vv.set_thruster_config()
+    vv.set_thruster_metrics()
+
+    me = MissionEnvironment.MissionEnvironment(CASE_DIR)
+    return jfh, tv, vv, me
+
+
+def face_areas(vectors):
+    v0, v1, v2 = vectors[:, 0], vectors[:, 1], vectors[:, 2]
+    return 0.5 * np.linalg.norm(np.cross(v1 - v0, v2 - v0), axis=1)
+
+
+def pipeline_row(result, centroids, normals, areas, tau_face, thruster_pos,
+                 alpha_deg):
+    """Eq.-15 averaged coefficients, peaks, and per-face field arrays from
+    one firing. Returns (coeffs, peaks, face_fields); face_fields holds
+    the case-frame per-face arrays for VTK (Cf1_case/Cf2_case un-flipped,
+    matching the actual mesh, unlike the paper-convention aggregates)."""
+    S_tot = float(np.sum(areas))
+    Cp = result['pressures'] / piu.Q_DYN
+    Csh = result['shear_stress'] / piu.Q_DYN
+    Cq = result['heat_flux_rate'] / piu.Q_DYN_HEAT
+
+    # signed shear components along the plate axes (tangential projection
+    # of the radial flow direction, as in the Phase-1 overlays)
+    rel = centroids - thruster_pos
+    dist = np.linalg.norm(rel, axis=1)
+    u_hat = rel / dist[:, None]
+    n_in = -NORMAL_OUT
+    cos_inc = u_hat @ n_in
+    t_vec = u_hat - cos_inc[:, None] * n_in
+    t_norm = np.linalg.norm(t_vec, axis=1)
+    safe = t_norm > 1e-12
+    t_hat = np.zeros_like(t_vec)
+    t_hat[safe] = t_vec[safe] / t_norm[safe, None]
+    Cf1 = Csh * (t_hat @ TANGENT_TAU)
+    Cf2 = Csh * (t_hat @ TANGENT_S)
+
+    flip = -1.0 if alpha_deg > 0 else 1.0   # into the paper convention
+    CP = float(np.sum(Cp * areas) / S_tot)
+    CF1 = flip * float(np.sum(Cf1 * areas) / S_tot)
+    CF2 = float(np.sum(Cf2 * areas) / S_tot)
+    CQ = float(np.sum(Cq * areas) / S_tot)
+    CM = flip * float(np.sum(tau_face * Cp * areas) / (2.0 * H_0 * S_tot))
+    s_cc = CM / CP if CP != 0.0 else float('nan')
+
+    face_fields = {
+        'strikes': result['strikes'],
+        'pressure_Pa': result['pressures'],
+        'shear_Pa': result['shear_stress'],
+        'heat_flux_W_m2': result['heat_flux_rate'],
+        'Cp': Cp,
+        'Cshear': Csh,
+        'Cf1_case': Cf1,
+        'Cf2_case': Cf2,
+        'Cq': Cq,
+    }
+    return ({'CP': CP, 'CF1': CF1, 'CF2': CF2, 'CQ': CQ, 'CM': CM,
+             's_cc': s_cc},
+            {'peak_Cp': float(np.max(Cp)), 'peak_Cshear': float(np.max(Csh)),
+             'peak_Cq': float(np.max(Cq)),
+             'n_struck': int(np.count_nonzero(result['strikes']))},
+            face_fields)
+
+
+def write_pose_vtk(target, face_fields, base_name):
+    """Write one pose's per-face fields to STRIKES_DIR/<base_name>.vtu via the
+    shared convert_stl_to_vtk writer (pyevtk needs C-contiguous float64)."""
+    cell_data = {k: np.ascontiguousarray(v, dtype=np.float64)
+                 for k, v in face_fields.items()}
+    convert_stl_to_vtk(target, STRIKES_DIR, filename=base_name,
+                       cellData=cell_data)
+
+
+def write_pvd(path, entries):
+    """ParaView collection grouping (timestep, relative_vtu_path) entries."""
+    lines = ['<?xml version="1.0"?>',
+             '<VTKFile type="Collection" version="0.1" '
+             'byte_order="LittleEndian">', '  <Collection>']
+    for timestep, rel_file in sorted(entries):
+        lines.append(f'    <DataSet timestep="{timestep:g}" group="" '
+                     f'part="0" file="{rel_file}"/>')
+    lines += ['  </Collection>', '</VTKFile>']
+    path.write_text('\n'.join(lines) + '\n', encoding='utf-8')
+
+
+def reference_rows():
+    """Exact Eq.-15 coefficients per (|alpha|, L), cached (mirror-invariant)."""
+    cache = {}
+    for L in L_OVER_D:
+        for abs_alpha in sorted({abs(a) for a in ALPHAS_DEG}):
+            alpha_paper = np.deg2rad(90.0 - abs_alpha)
+            cache[(abs_alpha, L)] = cai.averaged_coefficients(
+                piu.S_0, alpha_paper, piu.EPS, piu.R_0, L, W_0, H_0)
+    return cache
+
+
+def check_mirror_symmetry(rows):
+    """Results must be mirror-symmetric in +/-alpha (paper convention).
+
+    The +/-90 deg poses are excluded: their strike membership comes from
+    float32-epsilon signs in the facing test, which are not mirrored.
+    CF2 is checked separately -- it vanishes identically by symmetry, so
+    normalizing its asymmetry by its own (noise) scale is meaningless.
+    """
+    worst = 0.0
+    for L in L_OVER_D:
+        by_alpha = {r['alpha_deg']: r for r in rows if r['L_over_D'] == L
+                    and abs(r['alpha_deg']) < 90.0}
+        cp_scale = max(abs(r['CP_pipe']) for r in by_alpha.values())
+        # tolerance covers the triangulation's O(h^2) s-asymmetry (the
+        # cell-diagonal split is not mirror-invariant)
+        assert max(abs(r['CF2_pipe']) for r in by_alpha.values()) \
+            < 1e-4 * cp_scale, f'CF2 not ~0 at L/D={L}'
+        for a in ALPHAS_DEG[(ALPHAS_DEG > 0) & (ALPHAS_DEG < 90.0)]:
+            for name in ('CP', 'CF1', 'CQ', 'CM'):
+                lo, hi = by_alpha[-a][f'{name}_pipe'], by_alpha[a][f'{name}_pipe']
+                scale = max(abs(v) for r in by_alpha.values()
+                            for v in [r[f'{name}_pipe']])
+                scale = max(scale, 1e-6 * cp_scale)
+                worst = max(worst, abs(hi - lo) / scale)
+    # tolerance: the JFH file stores DCMs to 6 significant digits (and
+    # positions to 9), so mirrored poses reproduce to ~1e-6 relative;
+    # a convention error would show up as O(1).
+    assert worst < 1e-5, f'mirror symmetry violated: {worst:.3g}'
+    return worst
+
+
+def plot_coefficients(rows, out_dir):
+    style_note = 'solid + markers: pipeline    dashed: Cai 2016 reference'
+    labels = {'CP': r'$C_P$', 'CF1': r'$C_{F1}$', 'CF2': r'$C_{F2}$',
+              'CQ': r'$C_Q$', 'CM': r'$C_M$', 's_cc': r'$s_{cc}$'}
+    for name in COEFF_NAMES:
+        fig, ax = plt.subplots(figsize=(7, 4.5))
+        for color, L in zip(PALETTE, L_OVER_D):
+            sub = sorted((r for r in rows if r['L_over_D'] == L
+                          and abs(r['alpha_deg']) < 90.0),
+                         key=lambda r: r['alpha_deg'])
+            a = [r['alpha_deg'] for r in sub]
+            ax.plot(a, [r[f'{name}_pipe'] for r in sub], '-o', color=color,
+                    lw=2, ms=4, label=f'L/D = {L:g}')
+            ax.plot(a, [r[f'{name}_ref'] for r in sub], '--', color=color,
+                    lw=2)
+            ax.annotate(f'{L:g}', (a[-1], sub[-1][f'{name}_pipe']),
+                        textcoords='offset points', xytext=(6, 0),
+                        color=color, fontsize=8, va='center')
+        ax.axhline(0.0, color='0.85', lw=0.8, zorder=0)
+        ax.set_xlabel(r'$\alpha$ (deg), 0 = head-on')
+        ax.set_ylabel(labels[name])
+        ax.set_title(f'Plate-averaged {labels[name]} vs approach angle\n'
+                     f'{style_note}', fontsize=10)
+        ax.set_xticks(np.arange(-90, 91, 30))
+        ax.legend(fontsize=8, title='distance', title_fontsize=8)
+        fig.savefig(out_dir / f'coeff_{name}.png', dpi=200,
+                    bbox_inches='tight')
+        plt.close(fig)
+
+
+def plot_peaks(rows, out_dir):
+    quantities = [('peak_Cp', r'peak $C_p$'),
+                  ('peak_Cshear', r'peak $|C_f|$'),
+                  ('peak_Cq', r'peak $C_q$')]
+    fig, axes = plt.subplots(3, 1, figsize=(7, 9), sharex=True)
+    for ax, (key, label) in zip(axes, quantities):
+        for color, L in zip(PALETTE, L_OVER_D):
+            sub = sorted((r for r in rows if r['L_over_D'] == L
+                          and abs(r['alpha_deg']) < 90.0),
+                         key=lambda r: r['alpha_deg'])
+            ax.plot([r['alpha_deg'] for r in sub], [r[key] for r in sub],
+                    '-o', color=color, lw=2, ms=4, label=f'L/D = {L:g}')
+        ax.set_ylabel(label)
+        ax.set_yscale('log')
+    axes[0].legend(fontsize=8, title='distance', title_fontsize=8)
+    axes[0].set_title('Peak per-face coefficients vs approach angle '
+                      '(pipeline)', fontsize=10)
+    axes[-1].set_xlabel(r'$\alpha$ (deg), 0 = head-on')
+    axes[-1].set_xticks(np.arange(-90, 91, 30))
+    fig.savefig(out_dir / 'peaks.png', dpi=200, bbox_inches='tight')
+    plt.close(fig)
+
+
+def main(write_vtk=True):
+    t_start = time.perf_counter()
+    jfh, tv, vv, me = load_case()
+    n_firings = len(jfh.JFH)
+    assert n_firings == len(ALPHAS_DEG) * len(L_OVER_D), (
+        f'unexpected sweep JFH length {n_firings}; regenerate with '
+        'case/plume/plume_inclined_plate/jfh/generate_sweep_jfh.py')
+
+    target = tv.mesh
+    normals = target.get_unit_normals()
+    centroids = compute_face_centroids(target.vectors)
+    areas = face_areas(target.vectors)
+    tau_face = (centroids - PLATE_CENTER) @ TANGENT_TAU
+
+    if write_vtk:
+        STRIKES_DIR.mkdir(parents=True, exist_ok=True)
+    pvd_entries = {}   # L/D -> [(alpha_deg, relative vtu path)]
+
+    print(f'reference curves: {len(set(abs(ALPHAS_DEG)))} angles x '
+          f'{len(L_OVER_D)} distances (Eq. 15 quadrature) ...')
+    t0 = time.perf_counter()
+    ref_cache = reference_rows()
+    t_ref = time.perf_counter() - t0
+    print(f'  done in {t_ref:.1f} s')
+
+    rows = []
+    t0 = time.perf_counter()
+    for i in range(n_firings):
+        L = L_OVER_D[i // len(ALPHAS_DEG)]
+        alpha_deg = float(ALPHAS_DEG[i % len(ALPHAS_DEG)])
+        step = {'thrusters': jfh.JFH[i]['thrusters'],
+                'xyz': np.array(jfh.JFH[i]['xyz']),
+                'dcm': np.array(jfh.JFH[i]['dcm']),
+                't': float(jfh.JFH[i]['t'])}
+        t_f = time.perf_counter()
+        result = compute_plume_strikes(target, normals, vv, step, me,
+                                       face_centroids=centroids)
+        dt = time.perf_counter() - t_f
+
+        coeffs, peaks, face_fields = pipeline_row(
+            result, centroids, normals, areas, tau_face, step['xyz'],
+            alpha_deg)
+        ref = ref_cache[(abs(alpha_deg), L)]
+        row = {'alpha_deg': alpha_deg, 'L_over_D': L,
+               'alpha_paper_deg': 90.0 - abs(alpha_deg),
+               'wall_time_s': dt, **peaks}
+        for name in COEFF_NAMES:
+            row[f'{name}_pipe'] = coeffs[name]
+            row[f'{name}_ref'] = float(ref[name])
+        rows.append(row)
+
+        if write_vtk:
+            base = f'firing-{i}'   # strict JFH-index numbering
+            write_pose_vtk(target, face_fields, base)
+            pvd_entries.setdefault(L, []).append(
+                (alpha_deg, f'{base}.vtu'))
+    t_sweep = time.perf_counter() - t0
+
+    # sanity: report the edge-on poses (strike membership is
+    # epsilon-arbitrary there, see the module docstring); mirror symmetry
+    head_on = {r['L_over_D']: r['CP_pipe'] for r in rows
+               if r['alpha_deg'] == 0.0}
+    for r in rows:
+        if abs(r['alpha_deg']) == 90.0:
+            print(f"edge-on alpha={r['alpha_deg']:+.0f}, "
+                  f"L/D={r['L_over_D']:g}: {r['n_struck']} faces pass the "
+                  f"epsilon-degenerate facing test; CP="
+                  f"{r['CP_pipe']:.3e} (head-on "
+                  f"{head_on[r['L_over_D']]:.3e}), peak Cp="
+                  f"{r['peak_Cp']:.3e}, peak |Cf|={r['peak_Cshear']:.3e}")
+    worst = check_mirror_symmetry(rows)
+    print(f'mirror-symmetry check: worst normalized asymmetry {worst:.2e}')
+
+    RESULTS_DIR.mkdir(parents=True, exist_ok=True)
+    columns = list(rows[0].keys())
+    csv_path = RESULTS_DIR / 'sweep_coefficients.csv'
+    with open(csv_path, 'w', encoding='utf-8', newline='') as fh:
+        writer = csv.DictWriter(fh, fieldnames=columns)
+        writer.writeheader()
+        writer.writerows(rows)
+    print(f'wrote {csv_path}')
+
+    plot_coefficients(rows, RESULTS_DIR)
+    plot_peaks(rows, RESULTS_DIR)
+    print(f'wrote coefficient and peak plots to {RESULTS_DIR}')
+
+    if write_vtk:
+        for L, entries in pvd_entries.items():
+            write_pvd(STRIKES_DIR / f'sweep_LoD{int(L):02d}.pvd', entries)
+        print(f'wrote {n_firings} per-pose strike VTK files to {STRIKES_DIR} '
+              f'(+ {len(pvd_entries)} sweep_LoD*.pvd collections)')
+
+    n_faces = len(target.vectors)
+    print(f'timings: {n_firings} firings x {n_faces} faces -- sweep '
+          f'{t_sweep:.1f} s ({t_sweep / n_firings * 1e3:.0f} ms/firing), '
+          f'reference {t_ref:.1f} s, total '
+          f'{time.perf_counter() - t_start:.1f} s')
+
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser(description=__doc__.splitlines()[0])
+    parser.add_argument('--no-vtk', action='store_true',
+                        help='skip the per-pose VTK export (CSV + plots '
+                             'only)')
+    args = parser.parse_args()
+    main(write_vtk=not args.no_vtk)
diff --git a/tests/README.md b/tests/README.md
index 7d007bc..ffcecf1 100644
--- a/tests/README.md
+++ b/tests/README.md
@@ -41,6 +41,20 @@ This dashboard provides an overview of all tests in the PyRPOD project, categori
 | `plume_integration_test_01.py`  | Integration    | Tests plume modeling in integrated systems.  | ❌     |
 | `plume_unit_test_01.py`         | Unit           | Verifies individual plume calculation methods.| ❌     |
 | `plume_verification_test_01.py` | Verification   | Validates plume outputs against benchmarks.  | ❌     |
+| `plume_verification_test_28.py` | Verification   | Cai 2016 Fig. 17: diffuse-plate Cp contours (manual-run figure). | ✅     |
+| `plume_verification_test_29.py` | Verification   | Cai 2016 Fig. 18: specular-plate Cp contours (manual-run figure). | ✅     |
+| `plume_verification_test_30.py` | Verification   | Cai 2016 Fig. 19: diffuse-plate Cf1 contours (manual-run figure). | ✅     |
+| `plume_verification_test_31.py` | Verification   | Cai 2016 Fig. 20: diffuse-plate Cf2 contours (manual-run figure). | ✅     |
+| `plume_verification_test_32.py` | Verification   | Cai 2016 Fig. 21: diffuse-plate Cq contours (manual-run figure). | ✅     |
+| `plume_verification_test_33.py` | Verification   | Cai 2016 Fig. 5: 2D diffuse-plate flowfield T contours (manual-run figure). | ✅     |
+| `plume_verification_test_34.py` | Verification   | Cai 2016 Fig. 6: 2D specular-plate flowfield T contours (manual-run figure). | ✅     |
+| `plume_verification_test_35.py` | Verification   | Cai 2016 Fig. 7: 2D diffuse-plate Cp profiles (manual-run figure). | ✅     |
+| `plume_verification_test_36.py` | Verification   | Cai 2016 Fig. 8: 2D specular-plate Cp profiles (manual-run figure). | ✅     |
+| `plume_verification_test_37.py` | Verification   | Cai 2016 Fig. 9: 2D diffuse-plate Cf profiles (manual-run figure). | ✅     |
+| `plume_verification_test_38.py` | Verification   | Cai 2016 Fig. 10: 2D diffuse-plate Cq profiles (manual-run figure). | ✅     |
+| `plume_verification_test_39.py` | Verification   | Cai 2016 Fig. 15: 3D diffuse-plate flowfield p contours (manual-run figure). | ✅     |
+| `plume_verification_test_40.py` | Verification   | Cai 2016 Fig. 16: 3D specular-plate flowfield p contours (manual-run figure). | ✅     |
+| `plume_impingement_error_summary.py` | Verification | Cai 2016 reference vs PyRPOD-chain max/mean error table (manual-run generator). | ✅     |
 
 ---
 
@@ -51,6 +65,7 @@ This dashboard provides an overview of all tests in the PyRPOD project, categori
 | `rpod_integration_test_02.py`   | Integration    | Asserts plume strikes for notional 1D approach.      | ✅     |
 | `rpod_integration_test_03.py`   | Integration    | Asserts plume strikes using KOZ geometry.            | ✅     |
 | `rpod_integration_test_04.py`   | Integration    | Asserts plume strikes using hollow cube geometry.    | ✅     |
+| `rpod_integration_test_07.py`   | Integration    | Cai 2016 inclined-plate case: pipeline loads vs exact reference. | ✅     |
 | `rpod_unit_test_01.py`          | Unit           | Verifies STL to VTK data conversion.                 | ✅     |
 | `rpod_unit_test_02.py`          | Unit           | Verifiy behavior of JFH reader.                      | ✅     |
 | `rpod_unit_test_03.py`          | Unit           | Produces JFH data according to produced equation.    | ⏳     |
diff --git a/tests/plume/data/digitized/README.md b/tests/plume/data/digitized/README.md
index 9f43dd1..29c2d9a 100644
--- a/tests/plume/data/digitized/README.md
+++ b/tests/plume/data/digitized/README.md
@@ -5,6 +5,18 @@ Drop digitized curves from Cai & Wang 2012 (JSR 49(1), DOI
 (`tests/plume/plume_verification_test_04` ... `_27`) will overlay them
 automatically on their next run. No code changes are needed.
 
+The same convention serves the Cai 2016 impingement figures
+(Aerospace 3(4):43, DOI 10.3390/aerospace3040043) reproduced by
+`plume_verification_test_28` ... `_40`, with a `cai16_` stem prefix so
+the 2016 paper's figure numbers never collide with the 2012 slots
+above: `cai16_fig05_*.csv` ... `cai16_fig10_*.csv` (Section 3, 2D
+planar plate), `cai16_fig15_*.csv`, `cai16_fig16_*.csv` (flowfield
+pressure contours), and `cai16_fig17_*.csv` ... `cai16_fig21_*.csv`
+(3D plate surface coefficients). One CSV per digitized DSMC/analytic
+curve or contour polyline in the figure's plotted units, e.g.
+`cai16_fig17_dsmc_0p2.csv` for the Cp = 0.2 line of the 2016 Fig. 17,
+or `cai16_fig07_dsmc.csv` for the DSMC Cp profile of the 2016 Fig. 7.
+
 ## File convention
 
 - Name: `<figstem>_<series>.csv`, where `<figstem>` is the paper figure
diff --git a/tests/plume/plume_figure_utils.py b/tests/plume/plume_figure_utils.py
index 194772e..0ac8a75 100644
--- a/tests/plume/plume_figure_utils.py
+++ b/tests/plume/plume_figure_utils.py
@@ -77,6 +77,11 @@
 BOLTZMANN = 1.380649e-23  # J / K
 
 OUTPUT_DIR = _THIS_DIR / 'output'
+# Cai & Wang 2012 figures live in their own output subfolder, parallel to
+# the Cai 2016 impingement set in output/Cai2016 (see
+# plume_impingement_utils.OUTPUT_DIR). OUTPUT_DIR itself stays the shared
+# output root so that derived path is unaffected.
+CAI2012_DIR = OUTPUT_DIR / 'Cai2012'
 DIGITIZED_DIR = _THIS_DIR / 'data' / 'digitized'
 
 X_MIN_OVER_D = 0.05    # models require X > 0
@@ -381,9 +386,9 @@ def annotate_error(ax, text, loc='lower left'):
 
 
 def save_figure(fig, name):
-    """Save PNG to tests/plume/output and return the path."""
-    OUTPUT_DIR.mkdir(parents=True, exist_ok=True)
-    path = OUTPUT_DIR / f'{name}.png'
+    """Save PNG to tests/plume/output/Cai2012 and return the path."""
+    CAI2012_DIR.mkdir(parents=True, exist_ok=True)
+    path = CAI2012_DIR / f'{name}.png'
     fig.savefig(path, dpi=200, bbox_inches='tight')
     plt.close(fig)
     return path
diff --git a/tests/plume/plume_impingement_error_summary.py b/tests/plume/plume_impingement_error_summary.py
new file mode 100644
index 0000000..04fbb40
--- /dev/null
+++ b/tests/plume/plume_impingement_error_summary.py
@@ -0,0 +1,108 @@
+# ========================
+# PyRPOD: tests/plume/plume_impingement_error_summary.py
+# ========================
+# Extends the model-vs-model error-summary pattern of
+# plume_verification_error_summary.py to the Cai 2016 inclined-plate
+# impingement study (Figs. 17-21 conditions): maximum and mean relative
+# differences between the exact reference surface coefficients
+# (pyrpod/plume/CaiImpingement2016.py, Eqs. 9-14) and the current
+# PyRPOD approximation (SimplifiedGasKinetics field + Shen/Maxwellian
+# wall formulas at the true incidence angle -- the Phase-2-fixed strike
+# pipeline chain), over the plate contour grid.
+#
+# As in the 2012 summary, each row restricts the comparison to the
+# region where the reference magnitude is at least 5% of its peak: the
+# largest relative differences otherwise occur near the plate corners
+# and sign-change lines where the reference value is near zero.
+# DSMC reference columns are pending digitized data
+# (tests/plume/data/digitized/fig17_*.csv ... fig21_*.csv).
+#
+# The filename intentionally avoids pytest's collection patterns
+# (test_*.py / *_test_*.py): this is a manual-run generator --
+#     python tests/plume/plume_impingement_error_summary.py
+# It writes tests/plume/output/Cai2016/cai2016_error_summary.csv and .md.
+
+import numpy as np
+
+import plume_impingement_utils as u
+from pyrpod.plume import CaiImpingement2016 as cai
+
+
+def build_rows():
+    # module self-verification first: quadrature convergence, symmetry,
+    # specular identity, and the n_w flux balance (raises on failure)
+    cai.run_sanity_checks(u.S_0, u.ALPHA_0, u.EPS, u.R_0, u.L_PLATE,
+                          verbose=False)
+
+    ref = u.reference_grid()
+    chain_d = u.chain_grid()            # diffuse chain (sigma = 1)
+    chain_s = u.chain_grid(sigma=0.0)   # specular chain for Cp,s
+
+    ref_shear = np.hypot(ref['Cf1_d'], ref['Cf2_d'])
+    comparisons = [
+        ('Cp,d (Fig. 17)', chain_d['Cp'], ref['Cp_d']),
+        ('Cp,s (Fig. 18)', chain_s['Cp'], ref['Cp_s']),
+        ('Cf1,d (Fig. 19)', chain_d['Cf1'], ref['Cf1_d']),
+        ('Cf2,d (Fig. 20)', chain_d['Cf2'], ref['Cf2_d']),
+        ('|Cf,d| (shear magnitude)', chain_d['Cshear'], ref_shear),
+        ('Cq,d (Fig. 21)', chain_d['Cq'], ref['Cq_d']),
+    ]
+
+    rows = []
+    for quantity, chain, reference in comparisons:
+        mask = u.significant_mask(reference)
+        rows.append({
+            'quantity': quantity,
+            'comparison': 'PyRPOD chain vs Cai 2016 exact',
+            'max_rel_diff': u.base.max_rel_diff(chain[mask],
+                                                reference[mask]),
+            'mean_rel_diff': u.mean_rel_diff(chain, reference, mask),
+            'restriction': '|ref| >= 5% of peak',
+            'vs_DSMC': 'pending digitized data',
+        })
+    return rows
+
+
+def write_summary():
+    rows = build_rows()
+    u.OUTPUT_DIR.mkdir(parents=True, exist_ok=True)
+    columns = ['quantity', 'comparison', 'max_rel_diff', 'mean_rel_diff',
+               'restriction', 'vs_DSMC']
+
+    csv_path = u.OUTPUT_DIR / 'cai2016_error_summary.csv'
+    with open(csv_path, 'w', encoding='utf-8', newline='') as fh:
+        fh.write(','.join(columns) + '\n')
+        for row in rows:
+            fh.write(','.join(
+                f'{row[c]:.4g}' if isinstance(row[c], float) else str(row[c])
+                for c in columns) + '\n')
+
+    md_path = u.OUTPUT_DIR / 'cai2016_error_summary.md'
+    with open(md_path, 'w', encoding='utf-8', newline='') as fh:
+        fh.write('# Cai 2016 impingement error summary '
+                 '(reference vs PyRPOD chain)\n\n')
+        fh.write('Section-4 conditions: argon, D = 1 m, S0 = 2.0, '
+                 'L = 4D, alpha0 = 60 deg, Tw/T0 = 1.5, 8 m x 8 m '
+                 'plate, contour grid '
+                 f'{u.GRID_N}x{u.GRID_N}. DSMC reference columns are '
+                 'pending digitized data.\n\n')
+        fh.write('| ' + ' | '.join(columns) + ' |\n')
+        fh.write('|' + '---|' * len(columns) + '\n')
+        for row in rows:
+            fh.write('| ' + ' | '.join(
+                f'{row[c]:.4g}' if isinstance(row[c], float) else str(row[c])
+                for c in columns) + ' |\n')
+        fh.write('\nNotes: the PyRPOD chain is the strike-pipeline '
+                 'computation (SimplifiedGasKinetics local field + '
+                 'Shen/Maxwellian wall model at the true incidence '
+                 'angle); Cp,s uses sigma = 0. Rows are restricted to '
+                 '|ref| >= 5% of the peak magnitude -- unrestricted '
+                 'maxima occur where the reference is near zero (plate '
+                 'corners, stagnation/sign-change lines), the same '
+                 'caveat as the 2012 summary.\n')
+    return csv_path, md_path
+
+
+if __name__ == '__main__':
+    for path in write_summary():
+        print(f'wrote {path}')
diff --git a/tests/plume/plume_impingement_utils.py b/tests/plume/plume_impingement_utils.py
new file mode 100644
index 0000000..37cf6be
--- /dev/null
+++ b/tests/plume/plume_impingement_utils.py
@@ -0,0 +1,374 @@
+# ========================
+# PyRPOD: tests/plume/plume_impingement_utils.py
+# ========================
+# Shared helpers for the manual-run verification figure scripts
+# plume_verification_test_28 ... _32, which reproduce Figs. 17-21 of
+# Cai, C., "Gaskinetic Modeling on Dilute Gaseous Plume Impingement
+# Flows," Aerospace 2016, 3(4), 43, doi:10.3390/aerospace3040043
+# (Section 4: round jet impinging on an inclined rectangular plate).
+#
+# Design notes
+# ------------
+# * Paper validation conditions (Sec. 4): argon, D = 1.0 m, L = 4D,
+#   plate 8 m x 8 m (W0 = H0 = L), T0 = 200 K, S0 = 2.0, Tw = 300 K
+#   (eps = 1.5), alpha0 = 60 deg, fully diffuse plate. All plotted
+#   quantities are the paper's dimensionless coefficients, so n_0 is
+#   inert; 1e20 m^-3 matches plume_figure_utils.
+# * The exact reference curves delegate to
+#   pyrpod/plume/CaiImpingement2016.py (Eqs. 9-14); that module's
+#   docstring records the n_w interpretation and its validation.
+# * Every figure also overlays the CURRENT PYRPOD APPROXIMATION:
+#   SimplifiedGasKinetics local field values (evaluated at the plume
+#   coordinates distance / off-axis angle of each plate point) fed
+#   through the Shen/Maxwellian wall formulas at the TRUE incidence
+#   angle between the local flow direction (radial from the exit) and
+#   the inclined plate normal. This replicates exactly what the
+#   Phase-2-fixed strike pipeline computes per struck face, so the
+#   pipeline comparison in tests/rpod is apples-to-apples with these
+#   figures. The Shen shear magnitude is decomposed onto the plate's
+#   (s, tau) axes along the tangential projection of the flow
+#   direction to compare with the paper's Cf1/Cf2 components.
+# * Specular figure (Fig. 18): the comparable Maxwellian setting is
+#   sigma = 0 (fully specular reflection) -- Shen's formulas then drop
+#   the wall-temperature term, matching the paper's remark that the
+#   plate temperature has no effect on Cp,s.
+# * Scripts _33.._40 reproduce the paper's remaining figures from the
+#   same single source of truth (pyrpod/plume/CaiImpingement2016.py):
+#   Figs. 5-6 (Section-3 2D flowfield temperature with a diffuse /
+#   specular plate), Figs. 7-10 (2D plate surface Cp/Cf/Cq profiles),
+#   and Figs. 15-16 (Section-4 flowfield pressure in the Y = 0 plane).
+#   The Section-3 validation geometry (slot 2H, L = 4*(2H), plate
+#   semi-width W = 5*(2H)) is read off the paper's figures -- see the
+#   reference module docstring. These figures have no PyRPOD-chain
+#   overlay: SimplifiedGasKinetics is a round-nozzle model (not
+#   comparable to the 2D slot jet) and the strike pipeline computes no
+#   flowfields-with-plates, so they are reference + digitized-DSMC
+#   reproductions only.
+# * Digitized-overlay slots follow tests/plume/data/digitized/README.md
+#   with the cai16_ stem prefix (the 2016 paper's figure numbers would
+#   otherwise collide with the 2012 slots): cai16_fig05_*.csv ...
+#   cai16_fig21_*.csv (absent files silently skipped).
+# * Generic figure plumbing (run_script, overlay_digitized,
+#   annotate_error, max_rel_diff) is reused from plume_figure_utils;
+#   only the paper-specific constants live here. Figures are saved to
+#   the study's own subfolder, tests/plume/output/Cai2016, to keep the
+#   Cai 2016 verification set separate from the 2012 figure outputs.
+
+import sys
+from pathlib import Path
+
+import numpy as np
+
+_THIS_DIR = Path(__file__).resolve().parent
+_REPO_ROOT = _THIS_DIR.parents[1]
+if str(_REPO_ROOT) not in sys.path:  # direct `python tests/plume/...py` runs
+    sys.path.insert(0, str(_REPO_ROOT))
+
+import plume_figure_utils as base  # noqa: E402
+from plume_figure_utils import plt  # noqa: E402
+from pyrpod.plume import CaiImpingement2016 as cai  # noqa: E402
+from pyrpod.plume.RarefiedPlumeGasKinetics import (  # noqa: E402
+    AVOGADROS_NUMBER,
+    GAS_CONSTANT,
+    SimplifiedGasKinetics,
+    get_maxwellian_heat_transfer,
+    get_maxwellian_pressure,
+    get_maxwellian_shear_pressure,
+)
+
+# Cai 2016 Section-4 validation conditions (argon)
+R_SPECIFIC = 208.13            # J / (kg K)
+GAMMA = 5.0 / 3.0
+T_0 = 200.0                    # K
+N_0 = 1.0e20                   # m^-3 (inert for the coefficients)
+D_NOZZLE = 1.0                 # m
+R_0 = D_NOZZLE / 2.0           # m
+S_0 = 2.0
+U_0 = S_0 * np.sqrt(2.0 * R_SPECIFIC * T_0)   # ~577.07 m/s
+T_W = 300.0                    # K
+EPS = T_W / T_0                # 1.5
+ALPHA_0 = np.deg2rad(60.0)
+L_PLATE = 4.0 * D_NOZZLE       # m
+W_0 = H_0 = L_PLATE            # plate semi-width/semi-length (8 m x 8 m)
+SIGMA = 1.0
+
+M_PARTICLE = (GAS_CONSTANT / R_SPECIFIC) / AVOGADROS_NUMBER  # kg
+Q_DYN = 0.5 * N_0 * M_PARTICLE * U_0 ** 2      # n0*m*U0^2/2 (Pa)
+Q_DYN_HEAT = 0.5 * N_0 * M_PARTICLE * U_0 ** 3  # n0*m*U0^3/2 (W/m^2)
+
+GRID_N = 81                    # nodes per plate axis for contour grids
+
+OUTPUT_DIR = base.OUTPUT_DIR / 'Cai2016'   # figure output subfolder
+
+# Section-3 (2D slot jet) validation geometry in units of the slot
+# height D2 = 2H (read off the paper's figures; see the reference
+# module docstring): L = 4*(2H), plate semi-width W = 5*(2H).
+D2_SLOT = 1.0
+H_SLOT = D2_SLOT / 2.0
+L_2D = 4.0 * D2_SLOT
+W_2D = 5.0 * D2_SLOT
+ALPHA_2D = np.deg2rad(60.0)    # Figs. 5-6 inclination
+
+#: paper-legend line styles for the four-parameter profile figures
+PROFILE_STYLES = ['-', '--', (0, (6, 2)), '-.']
+
+THRUSTER_CHARACTERISTICS = {'d': D_NOZZLE, 've': U_0, 'R': R_SPECIFIC,
+                            'gamma': GAMMA, 'Te': T_0, 'n': N_0}
+
+_SIN_A, _COS_A = np.sin(ALPHA_0), np.cos(ALPHA_0)
+#: plate inward normal (flow side -> plate) and in-plane axes in global coords
+NORMAL_IN = np.array([_SIN_A, 0.0, -_COS_A])
+TANGENT_TAU = np.array([_COS_A, 0.0, _SIN_A])
+TANGENT_S = np.array([0.0, 1.0, 0.0])
+
+
+def plate_axes(n=GRID_N):
+    """(s, tau) axes in meters (= diameters, D = 1 m) spanning the plate."""
+    return np.linspace(-W_0, W_0, n), np.linspace(-H_0, H_0, n)
+
+
+def reference_grid(n=GRID_N):
+    """Exact Cai 2016 coefficients on the (s, tau) tensor grid; returns
+    dict of arrays shaped (len(tau), len(s)) for plt.contour."""
+    s, tau = plate_axes(n)
+    Sg, Tg = np.meshgrid(s, tau)
+    return cai.surface_coefficients_plate(Sg, Tg, S_0, ALPHA_0, EPS, R_0,
+                                          L_PLATE)
+
+
+def chain_point_loads(X, Y, Z, sigma=SIGMA):
+    """Current-PyRPOD approximation at one global plate point (X, Y, Z):
+    SimplifiedGasKinetics field state at the point's plume coordinates,
+    Shen/Maxwellian wall loads at the true incidence angle.
+
+    Returns (pressure, shear_magnitude, heat_flux) in SI units. This is
+    the per-face computation of the Phase-2-fixed strike pipeline
+    (PlumeStrikeCalculator), kept in one helper so the figures and the
+    pipeline comparison test share a single definition.
+    """
+    dist = float(np.sqrt(X * X + Y * Y + Z * Z))
+    theta_pos = float(np.arctan2(np.hypot(Y, Z), X))
+    plume = SimplifiedGasKinetics(dist, theta_pos, THRUSTER_CHARACTERISTICS,
+                                  T_W, sigma)
+    if theta_pos != 0.0:
+        n_ratio = plume.get_num_density_ratio()
+        T = T_0 * plume.get_temp_ratio()
+        u = plume.get_U_normalized() / plume.beta_0
+        w = plume.get_W_normalized() / plume.beta_0
+        U = float(np.hypot(u, w))
+    else:
+        n_ratio = plume.get_num_density_centerline()
+        T = T_0 * plume.get_temp_centerline()
+        U = plume.get_velocity_centerline() / plume.beta_0
+    rho_inf = N_0 * n_ratio * M_PARTICLE
+    S = U * plume.get_beta(T)
+
+    cos_inc = (X * _SIN_A - Z * _COS_A) / dist   # flow dir . inward normal
+    incidence = float(np.arccos(np.clip(cos_inc, -1.0, 1.0)))
+
+    pressure = get_maxwellian_pressure(rho_inf, U, S, sigma, incidence,
+                                       T, T_W)
+    shear = abs(get_maxwellian_shear_pressure(rho_inf, U, S, sigma,
+                                              incidence))
+    heat = get_maxwellian_heat_transfer(rho_inf, S, sigma, incidence,
+                                        T, T_W, R_SPECIFIC, GAMMA)
+    return pressure, shear, heat
+
+
+def chain_grid(n=GRID_N, sigma=SIGMA):
+    """Current-PyRPOD approximation coefficients on the (s, tau) grid.
+
+    Returns dict with 'Cp', 'Cf1', 'Cf2', 'Cshear', 'Cq' shaped like
+    reference_grid arrays. The shear magnitude from Shen's formula acts
+    along the tangential projection of the (radial) flow direction; its
+    components on the plate axes give Cf1 (inclined direction) and Cf2
+    (horizontal), signed like the paper's Figs. 19-20.
+    """
+    s, tau = plate_axes(n)
+    Sg, Tg = np.meshgrid(s, tau)
+    X, Y, Z = cai.plate_point_coords(Sg, Tg, ALPHA_0, L_PLATE)
+
+    Cp = np.empty_like(X)
+    Cf1 = np.empty_like(X)
+    Cf2 = np.empty_like(X)
+    Csh = np.empty_like(X)
+    Cq = np.empty_like(X)
+    it = np.nditer(X, flags=['multi_index'])
+    for _ in it:
+        i = it.multi_index
+        x, y, z = float(X[i]), float(Y[i]), float(Z[i])
+        p, sh, q = chain_point_loads(x, y, z, sigma=sigma)
+        dist = np.sqrt(x * x + y * y + z * z)
+        u_hat = np.array([x, y, z]) / dist
+        cos_inc = float(u_hat @ NORMAL_IN)
+        t_vec = u_hat - cos_inc * NORMAL_IN
+        t_norm = np.linalg.norm(t_vec)
+        t_hat = t_vec / t_norm if t_norm > 1e-12 else np.zeros(3)
+        Cp[i] = p / Q_DYN
+        Csh[i] = sh / Q_DYN
+        Cf1[i] = sh * float(t_hat @ TANGENT_TAU) / Q_DYN
+        Cf2[i] = sh * float(t_hat @ TANGENT_S) / Q_DYN
+        Cq[i] = q / Q_DYN_HEAT
+    return {'Cp': Cp, 'Cf1': Cf1, 'Cf2': Cf2, 'Cshear': Csh, 'Cq': Cq}
+
+
+def save_figure(fig, name):
+    """Save PNG to tests/plume/output/Cai2016 and return the path."""
+    OUTPUT_DIR.mkdir(parents=True, exist_ok=True)
+    path = OUTPUT_DIR / f'{name}.png'
+    fig.savefig(path, dpi=200, bbox_inches='tight')
+    plt.close(fig)
+    return path
+
+
+def mean_rel_diff(candidate, reference, mask):
+    """mean |candidate - reference| / |reference| over the masked entries."""
+    candidate = np.asarray(candidate, dtype=float)
+    reference = np.asarray(reference, dtype=float)
+    m = mask & np.isfinite(candidate) & np.isfinite(reference)
+    return float(np.mean(np.abs(candidate[m] - reference[m])
+                         / np.abs(reference[m])))
+
+
+def significant_mask(reference, fraction=0.05):
+    """Entries where |reference| >= fraction * max|reference| -- the
+    region where relative errors are meaningful (the largest relative
+    differences otherwise sit in the near-zero plate corners, the same
+    caveat the 2012 error summary records)."""
+    reference = np.asarray(reference, dtype=float)
+    return np.abs(reference) >= fraction * np.max(np.abs(reference))
+
+
+def impingement_contour_figure(fig_stem, ref_field, chain_field, levels,
+                               title, file_name, chain_label='PyRPOD chain',
+                               fmt='%g'):
+    """Shared Figs. 17-21 builder: reference contours (solid black),
+    current-PyRPOD-approximation contours (dashed red, same levels),
+    digitized slots, and a max/mean relative-error annotation over the
+    significant region."""
+    s, tau = plate_axes()
+
+    fig, ax = plt.subplots(figsize=(6, 6))
+    cs = ax.contour(s, tau, ref_field, levels=levels, colors='k',
+                    linewidths=1.2)
+    ax.clabel(cs, fmt=fmt, fontsize=7)
+    ax.contour(s, tau, chain_field, levels=levels, colors='r',
+               linewidths=0.9, linestyles='dashed')
+    n_dig = base.overlay_digitized(ax, fig_stem, style='line')
+
+    ax.set_xlim(-W_0, W_0)
+    ax.set_ylim(-H_0, H_0)
+    ax.set_xlabel('s')
+    ax.set_ylabel(r'$\tau$')
+    ax.set_title(title)
+    handles = [plt.Line2D([], [], color='k', lw=1.2,
+                          label='Cai 2016 (exact)'),
+               plt.Line2D([], [], color='r', lw=0.9, ls='--',
+                          label=chain_label)]
+    if n_dig:
+        handles.append(plt.Line2D([], [], color='k', lw=1.0,
+                                  label='DSMC (digitized)'))
+    ax.legend(handles=handles, fontsize=7, loc='upper right')
+
+    mask = significant_mask(ref_field)
+    base.annotate_error(
+        ax,
+        f'max rel diff = {base.max_rel_diff(chain_field[mask], ref_field[mask]):.2g}\n'
+        f'mean rel diff = {mean_rel_diff(chain_field, ref_field, mask):.2g}\n'
+        r'(where $|C_{ref}| \geq$ 5% of peak)')
+    return save_figure(fig, file_name)
+
+
+def _draw_plate_trace(ax, alpha_0, L, semi_length):
+    """Plate trace in the plotted plane (2D plate line or the 3D plate's
+    Y = 0 section), drawn like the paper's contour figures."""
+    tau = np.array([-semi_length, semi_length])
+    ax.plot(L + tau * np.cos(alpha_0), tau * np.sin(alpha_0), 'k-', lw=1.6)
+
+
+def planar_temperature_contour_figure(plate, levels, fig_stem, file_name,
+                                      title, S_0=2.0, grid_n=161):
+    """Figs. 5-6 builder: 2D flowfield temperature contours T/T0 for the
+    slot jet with a diffuse or specular plate (delegates to
+    cai.planar_flowfield), solid black with labels, plate line drawn,
+    digitized slots overlaid."""
+    x = np.linspace(0.05, 8.0, grid_n)
+    y = np.linspace(-4.0, 4.0, grid_n)
+    Xg, Yg = np.meshgrid(x * D2_SLOT, y * D2_SLOT)
+    T = cai.planar_flowfield(Xg, Yg, S_0, ALPHA_2D, EPS, H_SLOT, L_2D,
+                             W_2D, plate=plate)['T']
+
+    fig, ax = plt.subplots(figsize=(6, 6))
+    cs = ax.contour(x, y, T, levels=levels, colors='k', linewidths=1.1)
+    ax.clabel(cs, fmt='%g', fontsize=7)
+    _draw_plate_trace(ax, ALPHA_2D, L_2D, W_2D)
+    n_dig = base.overlay_digitized(ax, fig_stem, style='line')
+
+    ax.set_xlim(0, 8)
+    ax.set_ylim(-4, 4)
+    ax.set_xlabel('X/(2H)')
+    ax.set_ylabel('Y/(2H)')
+    ax.set_title(title)
+    handles = [plt.Line2D([], [], color='k', lw=1.1, label='Analytical')]
+    if n_dig:
+        handles.append(plt.Line2D([], [], color='k', lw=1.0,
+                                  label='DSMC (digitized)'))
+    ax.legend(handles=handles, fontsize=7, loc='lower right')
+    return save_figure(fig, file_name)
+
+
+def planar_profile_figure(quantity, params, fig_stem, file_name, title,
+                          ylabel, ylim, n_s=401):
+    """Figs. 7-10 builder: 2D plate surface coefficient profiles vs
+    s/(2H) for (S_0, alpha_0 deg) parameter combinations (delegates to
+    cai.planar_surface_coefficients), paper-style black line styles,
+    digitized slots overlaid."""
+    s = np.linspace(-5.0, 5.0, n_s) * D2_SLOT
+
+    fig, ax = plt.subplots(figsize=(6, 4.5))
+    for (S_0, alpha_deg), ls in zip(params, PROFILE_STYLES):
+        coeffs = cai.planar_surface_coefficients(
+            s, S_0, np.deg2rad(alpha_deg), EPS, H_SLOT, L_2D)
+        ax.plot(s / D2_SLOT, coeffs[quantity], color='k', ls=ls, lw=1.1,
+                label=f'$S_0$={S_0:g}, {alpha_deg:g}$^\\circ$')
+    base.overlay_digitized(ax, fig_stem)
+
+    ax.set_xlim(-5, 6)
+    ax.set_ylim(*ylim)
+    ax.set_xlabel('s/(2H)')
+    ax.set_ylabel(ylabel)
+    ax.set_title(title)
+    ax.legend(fontsize=8)
+    return save_figure(fig, file_name)
+
+
+def pressure_contour_figure_3d(plate, levels, fig_stem, file_name, title,
+                               S_0=2.0, grid_n=141):
+    """Figs. 15-16 builder: Section-4 flowfield static-pressure contours
+    p/p0 in the vertical Y = 0 plane with a diffuse or specular plate
+    (delegates to cai.flowfield_pressure_plane), plate section drawn,
+    digitized slots overlaid."""
+    x = np.linspace(0.05, 8.0, grid_n)
+    z = np.linspace(-4.0, 4.0, grid_n)
+    Xg, Zg = np.meshgrid(x * D_NOZZLE, z * D_NOZZLE)
+    p = cai.flowfield_pressure_plane(
+        Xg, Zg, S_0, ALPHA_0, EPS, R_0, L_PLATE, W_0, H_0,
+        plate=plate)['p']
+
+    fig, ax = plt.subplots(figsize=(6, 6))
+    cs = ax.contour(x, z, p, levels=levels, colors='k', linewidths=1.1)
+    ax.clabel(cs, fmt='%g', fontsize=7)
+    _draw_plate_trace(ax, ALPHA_0, L_PLATE, H_0)
+    n_dig = base.overlay_digitized(ax, fig_stem, style='line')
+
+    ax.set_xlim(0, 8)
+    ax.set_ylim(-4, 4)
+    ax.set_xlabel('$X/(2R_0)$')
+    ax.set_ylabel('$W/(2R_0)$')
+    ax.set_title(title)
+    handles = [plt.Line2D([], [], color='k', lw=1.1, label='Analytical')]
+    if n_dig:
+        handles.append(plt.Line2D([], [], color='k', lw=1.0,
+                                  label='DSMC (digitized)'))
+    ax.legend(handles=handles, fontsize=7, loc='lower right')
+    return save_figure(fig, file_name)
diff --git a/tests/plume/plume_verification_error_summary.py b/tests/plume/plume_verification_error_summary.py
index b99b6d7..a3963e1 100644
--- a/tests/plume/plume_verification_error_summary.py
+++ b/tests/plume/plume_verification_error_summary.py
@@ -16,7 +16,7 @@
 # The filename intentionally avoids pytest's collection patterns
 # (test_*.py / *_test_*.py): this is a manual-run generator --
 #     python tests/plume/plume_verification_error_summary.py
-# It writes tests/plume/output/model_error_summary.csv and .md.
+# It writes tests/plume/output/Cai2012/model_error_summary.csv and .md.
 
 import numpy as np
 
@@ -77,11 +77,11 @@ def build_rows():
 
 def write_summary():
     rows = build_rows()
-    u.OUTPUT_DIR.mkdir(parents=True, exist_ok=True)
+    u.CAI2012_DIR.mkdir(parents=True, exist_ok=True)
     columns = ['curve', 'quantity', 'comparison', 'max_rel_diff',
                'max_rel_diff_restricted', 'restriction', 'vs_DSMC']
 
-    csv_path = u.OUTPUT_DIR / 'model_error_summary.csv'
+    csv_path = u.CAI2012_DIR / 'model_error_summary.csv'
     with open(csv_path, 'w', encoding='utf-8', newline='') as fh:
         fh.write(','.join(columns) + '\n')
         for row in rows:
@@ -89,7 +89,7 @@ def write_summary():
                 f'{row[c]:.4g}' if isinstance(row[c], float) else str(row[c])
                 for c in columns) + '\n')
 
-    md_path = u.OUTPUT_DIR / 'model_error_summary.md'
+    md_path = u.CAI2012_DIR / 'model_error_summary.md'
     with open(md_path, 'w', encoding='utf-8', newline='') as fh:
         fh.write('# Model-vs-model error summary (Table 1 analog)\n\n')
         fh.write(f'Cai & Wang 2012 conditions, S0 = {S_0}. DSMC reference '
diff --git a/tests/plume/plume_verification_test_04.py b/tests/plume/plume_verification_test_04.py
index 5978a31..0429d24 100644
--- a/tests/plume/plume_verification_test_04.py
+++ b/tests/plume/plume_verification_test_04.py
@@ -8,7 +8,7 @@
 # Manual-run verification script (design decision D5): it defines no
 # pytest tests and is executed directly --
 #     python tests/plume/plume_verification_test_04.py
-# The figure is saved to tests/plume/output/.
+# The figure is saved to tests/plume/output/Cai2012/.
 # Digitized overlays looked for: fig02_*.csv (none published -- Fig. 2
 # has no DSMC data in the paper).
 
diff --git a/tests/plume/plume_verification_test_28.py b/tests/plume/plume_verification_test_28.py
new file mode 100644
index 0000000..7e3a818
--- /dev/null
+++ b/tests/plume/plume_verification_test_28.py
@@ -0,0 +1,34 @@
+# ========================
+# PyRPOD: tests/plume/plume_verification_test_28.py
+# ========================
+# Reproduces Cai 2016 Fig. 17: diffuse-plate surface pressure contours
+# Cp,d(s, tau) for a round argon jet (D = 1 m, S0 = 2.0, T0 = 200 K) on
+# the 8 m x 8 m plate at L = 4D, alpha0 = 60 deg, Tw/T0 = 1.5 (Eq. 9,
+# solid black). Overlaid dashed red: the current PyRPOD approximation
+# (SimplifiedGasKinetics field + Shen/Maxwellian wall pressure at the
+# true incidence angle, sigma = 1) -- exactly what the fixed strike
+# pipeline computes per struck face.
+#
+# Manual-run verification script (design decision D5): no pytest tests;
+# run directly -- python tests/plume/plume_verification_test_28.py
+# Digitized overlays looked for: cai16_fig17_*.csv (e.g.
+# cai16_fig17_dsmc_0p2.csv, one CSV per digitized contour polyline; the
+# cai16_ prefix keeps the 2016 paper's slots distinct from the Cai &
+# Wang 2012 fig17 slot).
+
+import plume_impingement_utils as u
+
+
+def generate_figure():
+    ref = u.reference_grid()
+    chain = u.chain_grid()
+    levels = [0.005, 0.01, 0.05, 0.1, 0.2]
+    return u.impingement_contour_figure(
+        'cai16_fig17', ref['Cp_d'], chain['Cp'], levels,
+        'Diffuse plate $C_{p,d}(s,\\tau)$, $S_0$=2.0, '
+        '$T_w/T_0$=1.5, $\\alpha_0$=60$^\\circ$ (Fig. 17)',
+        'fig17_diffuse_pressure')
+
+
+if __name__ == '__main__':
+    u.base.run_script(generate_figure)
diff --git a/tests/plume/plume_verification_test_29.py b/tests/plume/plume_verification_test_29.py
new file mode 100644
index 0000000..858221e
--- /dev/null
+++ b/tests/plume/plume_verification_test_29.py
@@ -0,0 +1,32 @@
+# ========================
+# PyRPOD: tests/plume/plume_verification_test_29.py
+# ========================
+# Reproduces Cai 2016 Fig. 18: specular-plate surface pressure contours
+# Cp,s(s, tau) (Eq. 14, solid black) at the Section-4 conditions
+# (argon, D = 1 m, S0 = 2.0, L = 4D, alpha0 = 60 deg). Overlaid dashed
+# red: the current PyRPOD approximation with sigma = 0 -- Shen's
+# Maxwellian pressure reduces to the fully specular reflection, and,
+# consistent with the paper, the wall temperature drops out.
+#
+# Manual-run verification script (design decision D5): no pytest tests;
+# run directly -- python tests/plume/plume_verification_test_29.py
+# Digitized overlays looked for: cai16_fig18_*.csv (one CSV per
+# digitized contour polyline; cai16_ prefix avoids the 2012 fig18 slot).
+
+import plume_impingement_utils as u
+
+
+def generate_figure():
+    ref = u.reference_grid()
+    chain = u.chain_grid(sigma=0.0)
+    levels = [0.005, 0.01, 0.05, 0.1, 0.2, 0.3]
+    return u.impingement_contour_figure(
+        'cai16_fig18', ref['Cp_s'], chain['Cp'], levels,
+        'Specular plate $C_{p,s}(s,\\tau)$, $S_0$=2.0, '
+        '$\\alpha_0$=60$^\\circ$ (Fig. 18)',
+        'fig18_specular_pressure',
+        chain_label='PyRPOD chain ($\\sigma$=0)')
+
+
+if __name__ == '__main__':
+    u.base.run_script(generate_figure)
diff --git a/tests/plume/plume_verification_test_30.py b/tests/plume/plume_verification_test_30.py
new file mode 100644
index 0000000..964be20
--- /dev/null
+++ b/tests/plume/plume_verification_test_30.py
@@ -0,0 +1,33 @@
+# ========================
+# PyRPOD: tests/plume/plume_verification_test_30.py
+# ========================
+# Reproduces Cai 2016 Fig. 19: diffuse-plate friction coefficient
+# Cf1,d(s, tau) along the inclined direction (Eq. 11, solid black) at
+# the Section-4 conditions. The zero contour is the stagnation line
+# (tau ~ -2): gas flows up-plate above it (positive Cf1) and down-plate
+# below. Overlaid dashed red: the current PyRPOD approximation -- the
+# Shen/Maxwellian shear magnitude at the true incidence angle,
+# decomposed onto the inclined plate axis along the tangential
+# projection of the radial flow direction.
+#
+# Manual-run verification script (design decision D5): no pytest tests;
+# run directly -- python tests/plume/plume_verification_test_30.py
+# Digitized overlays looked for: cai16_fig19_*.csv (one CSV per
+# digitized contour polyline; cai16_ prefix avoids the 2012 fig19 slot).
+
+import plume_impingement_utils as u
+
+
+def generate_figure():
+    ref = u.reference_grid()
+    chain = u.chain_grid()
+    levels = [-0.001, 0.0, 0.001, 0.01, 0.05]
+    return u.impingement_contour_figure(
+        'cai16_fig19', ref['Cf1_d'], chain['Cf1'], levels,
+        'Diffuse plate $C_{f_1,d}(s,\\tau)$, $S_0$=2.0, '
+        '$T_w/T_0$=1.5, $\\alpha_0$=60$^\\circ$ (Fig. 19)',
+        'fig19_diffuse_friction_tau')
+
+
+if __name__ == '__main__':
+    u.base.run_script(generate_figure)
diff --git a/tests/plume/plume_verification_test_31.py b/tests/plume/plume_verification_test_31.py
new file mode 100644
index 0000000..2801257
--- /dev/null
+++ b/tests/plume/plume_verification_test_31.py
@@ -0,0 +1,32 @@
+# ========================
+# PyRPOD: tests/plume/plume_verification_test_31.py
+# ========================
+# Reproduces Cai 2016 Fig. 20: diffuse-plate friction coefficient
+# Cf2,d(s, tau) along the horizontal direction (Eq. 12, solid black) at
+# the Section-4 conditions -- antisymmetric in s (gas flows outward to
+# both sides of the vertical symmetry plane). Overlaid dashed red: the
+# current PyRPOD approximation, decomposed onto the horizontal plate
+# axis (see plume_verification_test_30 header).
+#
+# Manual-run verification script (design decision D5): no pytest tests;
+# run directly -- python tests/plume/plume_verification_test_31.py
+# Digitized overlays looked for: cai16_fig20_*.csv (one CSV per
+# digitized contour polyline; cai16_ prefix avoids the 2012 fig20 slot).
+
+import plume_impingement_utils as u
+
+
+def generate_figure():
+    ref = u.reference_grid()
+    chain = u.chain_grid()
+    levels = [-0.02, -0.01, -0.005, -0.001,
+              0.001, 0.005, 0.01, 0.02]
+    return u.impingement_contour_figure(
+        'cai16_fig20', ref['Cf2_d'], chain['Cf2'], levels,
+        'Diffuse plate $C_{f_2,d}(s,\\tau)$, $S_0$=2.0, '
+        '$T_w/T_0$=1.5, $\\alpha_0$=60$^\\circ$ (Fig. 20)',
+        'fig20_diffuse_friction_s')
+
+
+if __name__ == '__main__':
+    u.base.run_script(generate_figure)
diff --git a/tests/plume/plume_verification_test_32.py b/tests/plume/plume_verification_test_32.py
new file mode 100644
index 0000000..d4115af
--- /dev/null
+++ b/tests/plume/plume_verification_test_32.py
@@ -0,0 +1,30 @@
+# ========================
+# PyRPOD: tests/plume/plume_verification_test_32.py
+# ========================
+# Reproduces Cai 2016 Fig. 21: diffuse-plate heat-flux coefficient
+# Cq,d(s, tau) (Eq. 13, solid black) at the Section-4 conditions --
+# peak just beneath the plate center, as the paper notes. Overlaid
+# dashed red: the current PyRPOD approximation (SimplifiedGasKinetics
+# field + Shen/Maxwellian heat transfer at the true incidence angle).
+#
+# Manual-run verification script (design decision D5): no pytest tests;
+# run directly -- python tests/plume/plume_verification_test_32.py
+# Digitized overlays looked for: cai16_fig21_*.csv (one CSV per
+# digitized contour polyline; cai16_ prefix avoids the 2012 fig21 slot).
+
+import plume_impingement_utils as u
+
+
+def generate_figure():
+    ref = u.reference_grid()
+    chain = u.chain_grid()
+    levels = [0.001, 0.01, 0.05]
+    return u.impingement_contour_figure(
+        'cai16_fig21', ref['Cq_d'], chain['Cq'], levels,
+        'Diffuse plate $C_{q,d}(s,\\tau)$, $S_0$=2.0, '
+        '$T_w/T_0$=1.5, $\\alpha_0$=60$^\\circ$ (Fig. 21)',
+        'fig21_diffuse_heat_flux')
+
+
+if __name__ == '__main__':
+    u.base.run_script(generate_figure)
diff --git a/tests/plume/plume_verification_test_33.py b/tests/plume/plume_verification_test_33.py
new file mode 100644
index 0000000..acebd38
--- /dev/null
+++ b/tests/plume/plume_verification_test_33.py
@@ -0,0 +1,30 @@
+# ========================
+# PyRPOD: tests/plume/plume_verification_test_33.py
+# ========================
+# Reproduces Cai 2016 Fig. 5: temperature contours T/T0 for the 2D slot
+# jet (S0 = 2.0) impinging on the inclined DIFFUSE planar plate
+# (alpha0 = 60 deg, Tw/T0 = 1.5, L = 4*(2H), W = 5*(2H)) -- the combined
+# free-jet + wall-emission field of Section 3, with the stagnation
+# heating peaking at T/T0 ~ 2.4 in front of the plate. Delegates to
+# pyrpod/plume/CaiImpingement2016.planar_flowfield (single source of
+# truth); the analytic field is evaluated on the whole X > 0 plane with
+# no shadowing, exactly as the paper's contours are drawn.
+#
+# Manual-run verification script (design decision D5): no pytest tests;
+# run directly -- python tests/plume/plume_verification_test_33.py
+# Digitized overlays looked for: cai16_fig05_*.csv (one CSV per
+# digitized contour polyline).
+
+import plume_impingement_utils as u
+
+
+def generate_figure():
+    return u.planar_temperature_contour_figure(
+        'diffuse', [1.0, 1.4, 1.8, 2.0, 2.2, 2.4], 'cai16_fig05',
+        'cai16_fig05_planar_diffuse_temperature',
+        '2D jet on diffuse plate, $T/T_0$, $S_0$=2.0, '
+        '$\\alpha_0$=60$^\\circ$, $T_w/T_0$=1.5 (Fig. 5)')
+
+
+if __name__ == '__main__':
+    u.base.run_script(generate_figure)
diff --git a/tests/plume/plume_verification_test_34.py b/tests/plume/plume_verification_test_34.py
new file mode 100644
index 0000000..787d1da
--- /dev/null
+++ b/tests/plume/plume_verification_test_34.py
@@ -0,0 +1,31 @@
+# ========================
+# PyRPOD: tests/plume/plume_verification_test_34.py
+# ========================
+# Reproduces Cai 2016 Fig. 6: temperature contours T/T0 for the 2D slot
+# jet (S0 = 2.0) impinging on the inclined SPECULAR planar plate
+# (alpha0 = 60 deg, L = 4*(2H)) -- the free jet plus the paper's
+# virtual-nozzle construction (mirrored exit and drift, Eq. 7), whose
+# defining property is the contour symmetry about the plate line that
+# the module's sanity checks assert to machine precision; counterflow
+# stagnation heating peaks at T/T0 ~ 3.5. Delegates to
+# pyrpod/plume/CaiImpingement2016.planar_flowfield (single source of
+# truth).
+#
+# Manual-run verification script (design decision D5): no pytest tests;
+# run directly -- python tests/plume/plume_verification_test_34.py
+# Digitized overlays looked for: cai16_fig06_*.csv (one CSV per
+# digitized contour polyline).
+
+import plume_impingement_utils as u
+
+
+def generate_figure():
+    return u.planar_temperature_contour_figure(
+        'specular', [1.0, 1.5, 2.0, 2.5, 3.0, 3.5], 'cai16_fig06',
+        'cai16_fig06_planar_specular_temperature',
+        '2D jet on specular plate, $T/T_0$, $S_0$=2.0, '
+        '$\\alpha_0$=60$^\\circ$ (Fig. 6)')
+
+
+if __name__ == '__main__':
+    u.base.run_script(generate_figure)
diff --git a/tests/plume/plume_verification_test_35.py b/tests/plume/plume_verification_test_35.py
new file mode 100644
index 0000000..79dff66
--- /dev/null
+++ b/tests/plume/plume_verification_test_35.py
@@ -0,0 +1,31 @@
+# ========================
+# PyRPOD: tests/plume/plume_verification_test_35.py
+# ========================
+# Reproduces Cai 2016 Fig. 7: 2D diffuse-plate surface pressure
+# profiles Cp,d(s) (Eq. 2, with the A0-integral non-penetration wall
+# density) for (S0, alpha0) = (2.0, 60), (2.0, 30), (1.5, 60),
+# (1.5, 30) deg at Tw/T0 = 1.5 -- the profiles skew with smaller
+# inclination angle, peaking at ~0.93 for the DSMC-validated
+# (2.0, 60 deg) case. Delegates to
+# pyrpod/plume/CaiImpingement2016.planar_surface_coefficients (single
+# source of truth).
+#
+# Manual-run verification script (design decision D5): no pytest tests;
+# run directly -- python tests/plume/plume_verification_test_35.py
+# Digitized overlays looked for: cai16_fig07_*.csv (e.g.
+# cai16_fig07_dsmc.csv, the paper's S0 = 2.0 / 60 deg DSMC symbols).
+
+import plume_impingement_utils as u
+
+PARAMS = [(2.0, 60.0), (2.0, 30.0), (1.5, 60.0), (1.5, 30.0)]
+
+
+def generate_figure():
+    return u.planar_profile_figure(
+        'Cp_d', PARAMS, 'cai16_fig07', 'cai16_fig07_planar_cp_diffuse',
+        'Diffuse planar plate $C_{p,d}(s)$, $T_w/T_0$=1.5 (Fig. 7)',
+        '$C_p$', (0.0, 1.0))
+
+
+if __name__ == '__main__':
+    u.base.run_script(generate_figure)
diff --git a/tests/plume/plume_verification_test_36.py b/tests/plume/plume_verification_test_36.py
new file mode 100644
index 0000000..79cca26
--- /dev/null
+++ b/tests/plume/plume_verification_test_36.py
@@ -0,0 +1,30 @@
+# ========================
+# PyRPOD: tests/plume/plume_verification_test_36.py
+# ========================
+# Reproduces Cai 2016 Fig. 8: 2D specular-plate surface pressure
+# profiles Cp,s(s) (Eq. 8 -- twice the jet-only normal momentum flux,
+# wall temperature drops out) for (S0, alpha0) = (2.0, 60), (2.0, 30),
+# (1.5, 60), (1.5, 30) deg, peaking at ~1.23 for the DSMC-validated
+# (2.0, 60 deg) case. Delegates to
+# pyrpod/plume/CaiImpingement2016.planar_surface_coefficients (single
+# source of truth).
+#
+# Manual-run verification script (design decision D5): no pytest tests;
+# run directly -- python tests/plume/plume_verification_test_36.py
+# Digitized overlays looked for: cai16_fig08_*.csv (e.g.
+# cai16_fig08_dsmc.csv).
+
+import plume_impingement_utils as u
+
+PARAMS = [(2.0, 60.0), (2.0, 30.0), (1.5, 60.0), (1.5, 30.0)]
+
+
+def generate_figure():
+    return u.planar_profile_figure(
+        'Cp_s', PARAMS, 'cai16_fig08', 'cai16_fig08_planar_cp_specular',
+        'Specular planar plate $C_{p,s}(s)$ (Fig. 8)',
+        '$C_p$', (0.0, 1.25))
+
+
+if __name__ == '__main__':
+    u.base.run_script(generate_figure)
diff --git a/tests/plume/plume_verification_test_37.py b/tests/plume/plume_verification_test_37.py
new file mode 100644
index 0000000..634e2bf
--- /dev/null
+++ b/tests/plume/plume_verification_test_37.py
@@ -0,0 +1,31 @@
+# ========================
+# PyRPOD: tests/plume/plume_verification_test_37.py
+# ========================
+# Reproduces Cai 2016 Fig. 9: 2D diffuse-plate surface friction
+# profiles Cf,d(s) (Eq. 3) for (S0, alpha0) = (2.0, 60), (2.0, 30),
+# (1.5, 60), (1.5, 30) deg at Tw/T0 = 1.5. Smaller inclination angles
+# create larger friction; the (2.0, 60 deg) profile crosses zero near
+# s/(2H) ~ -2 (the paper's possible flow-separation spot; the module
+# anchor reproduces it at -2.12). Delegates to
+# pyrpod/plume/CaiImpingement2016.planar_surface_coefficients (single
+# source of truth).
+#
+# Manual-run verification script (design decision D5): no pytest tests;
+# run directly -- python tests/plume/plume_verification_test_37.py
+# Digitized overlays looked for: cai16_fig09_*.csv (e.g.
+# cai16_fig09_dsmc.csv).
+
+import plume_impingement_utils as u
+
+PARAMS = [(2.0, 60.0), (2.0, 30.0), (1.5, 60.0), (1.5, 30.0)]
+
+
+def generate_figure():
+    return u.planar_profile_figure(
+        'Cf_d', PARAMS, 'cai16_fig09', 'cai16_fig09_planar_cf_diffuse',
+        'Diffuse planar plate $C_{f,d}(s)$, $T_w/T_0$=1.5 (Fig. 9)',
+        '$C_f$', (-0.1, 0.4))
+
+
+if __name__ == '__main__':
+    u.base.run_script(generate_figure)
diff --git a/tests/plume/plume_verification_test_38.py b/tests/plume/plume_verification_test_38.py
new file mode 100644
index 0000000..8952487
--- /dev/null
+++ b/tests/plume/plume_verification_test_38.py
@@ -0,0 +1,31 @@
+# ========================
+# PyRPOD: tests/plume/plume_verification_test_38.py
+# ========================
+# Reproduces Cai 2016 Fig. 10: 2D diffuse-plate surface heat-flux
+# profiles Cq,d(s) (Eq. 4, incoming energy flux minus the wall-Maxwellian
+# effusion at Tw) for (S0, alpha0) = (2.0, 60), (2.0, 90), (1.5, 60),
+# (1.5, 90) deg at Tw/T0 = 1.5 -- the larger S0, the larger the heat
+# flux, peaking at ~0.27 for the DSMC-validated (2.0, 60 deg) case.
+# Delegates to
+# pyrpod/plume/CaiImpingement2016.planar_surface_coefficients (single
+# source of truth).
+#
+# Manual-run verification script (design decision D5): no pytest tests;
+# run directly -- python tests/plume/plume_verification_test_38.py
+# Digitized overlays looked for: cai16_fig10_*.csv (e.g.
+# cai16_fig10_dsmc.csv).
+
+import plume_impingement_utils as u
+
+PARAMS = [(2.0, 60.0), (2.0, 90.0), (1.5, 60.0), (1.5, 90.0)]
+
+
+def generate_figure():
+    return u.planar_profile_figure(
+        'Cq_d', PARAMS, 'cai16_fig10', 'cai16_fig10_planar_cq_diffuse',
+        'Diffuse planar plate $C_{q,d}(s)$, $T_w/T_0$=1.5 (Fig. 10)',
+        '$C_q$', (0.0, 0.3))
+
+
+if __name__ == '__main__':
+    u.base.run_script(generate_figure)
diff --git a/tests/plume/plume_verification_test_39.py b/tests/plume/plume_verification_test_39.py
new file mode 100644
index 0000000..72871f7
--- /dev/null
+++ b/tests/plume/plume_verification_test_39.py
@@ -0,0 +1,33 @@
+# ========================
+# PyRPOD: tests/plume/plume_verification_test_39.py
+# ========================
+# Reproduces Cai 2016 Fig. 15: static-pressure contours p/p0 in the
+# vertical Y = 0 plane for the Section-4 round jet (argon, D = 1 m,
+# S0 = 2.0) impinging on the inclined DIFFUSE rectangular plate
+# (alpha0 = 60 deg, L = 4D, Tw/T0 = 1.5) -- the free-jet field (2012
+# exit-disk integrals, imported from RarefiedPlumeGasKinetics) combined
+# with the Eq.-9 wall-emission population, showing the paper's gas
+# accumulation in the impingement center region (peak p/p0 ~ 0.58 just
+# below the plate center vs the paper's 0.5 innermost contour).
+# Delegates to
+# pyrpod/plume/CaiImpingement2016.flowfield_pressure_plane (single
+# source of truth).
+#
+# Manual-run verification script (design decision D5): no pytest tests;
+# run directly -- python tests/plume/plume_verification_test_39.py
+# Digitized overlays looked for: cai16_fig15_*.csv (one CSV per
+# digitized contour polyline).
+
+import plume_impingement_utils as u
+
+
+def generate_figure():
+    return u.pressure_contour_figure_3d(
+        'diffuse', [0.05, 0.1, 0.2, 0.4, 0.5], 'cai16_fig15',
+        'cai16_fig15_pressure_diffuse',
+        'Round jet on diffuse plate, $p/p_0$ in $Y$=0 plane, '
+        '$S_0$=2.0, $\\alpha_0$=60$^\\circ$ (Fig. 15)')
+
+
+if __name__ == '__main__':
+    u.base.run_script(generate_figure)
diff --git a/tests/plume/plume_verification_test_40.py b/tests/plume/plume_verification_test_40.py
new file mode 100644
index 0000000..cf9ad18
--- /dev/null
+++ b/tests/plume/plume_verification_test_40.py
@@ -0,0 +1,33 @@
+# ========================
+# PyRPOD: tests/plume/plume_verification_test_40.py
+# ========================
+# Reproduces Cai 2016 Fig. 16: static-pressure contours p/p0 in the
+# vertical Y = 0 plane for the Section-4 round jet (argon, D = 1 m,
+# S0 = 2.0) impinging on the inclined SPECULAR rectangular plate
+# (alpha0 = 60 deg, L = 4D) -- the free-jet field plus the paper's 3D
+# virtual nozzle at (L(1 - cos 2a0), 0, -L sin 2a0) with mirrored drift
+# (see the reference module docstring for the drift-sign resolution),
+# whose mirror symmetry about the plate plane the module's sanity
+# checks assert to machine precision; peak p/p0 ~ 0.50 vs the paper's
+# 0.4 innermost contour. Delegates to
+# pyrpod/plume/CaiImpingement2016.flowfield_pressure_plane (single
+# source of truth).
+#
+# Manual-run verification script (design decision D5): no pytest tests;
+# run directly -- python tests/plume/plume_verification_test_40.py
+# Digitized overlays looked for: cai16_fig16_*.csv (one CSV per
+# digitized contour polyline).
+
+import plume_impingement_utils as u
+
+
+def generate_figure():
+    return u.pressure_contour_figure_3d(
+        'specular', [0.01, 0.05, 0.1, 0.2, 0.3, 0.4], 'cai16_fig16',
+        'cai16_fig16_pressure_specular',
+        'Round jet on specular plate, $p/p_0$ in $Y$=0 plane, '
+        '$S_0$=2.0, $\\alpha_0$=60$^\\circ$ (Fig. 16)')
+
+
+if __name__ == '__main__':
+    u.base.run_script(generate_figure)
diff --git a/tests/rpod/rpod_integration_test_07.py b/tests/rpod/rpod_integration_test_07.py
new file mode 100644
index 0000000..d47cc6d
--- /dev/null
+++ b/tests/rpod/rpod_integration_test_07.py
@@ -0,0 +1,204 @@
+# ========================
+# PyRPOD: tests/rpod/rpod_integration_test_07.py
+# ========================
+# Cai 2016 inclined-plate verification: runs case/plume/plume_inclined_plate
+# (argon round jet, D = 1 m, S0 = 2.0, 8 m x 8 m plate at L = 4D inclined
+# 60 deg, Tw/T0 = 1.5, sigma = 1) through PlumeStrikeEstimationStudy,
+# converts the per-face dimensional loads to the paper's coefficient
+# normalization (pressure/shear by n0*m*U0^2/2, heat flux by n0*m*U0^3/2),
+# and compares face-by-face against the exact reference functions
+# (pyrpod/plume/CaiImpingement2016.py, Eqs. 9-13) evaluated at the face
+# centroids.
+#
+# Hard assertions cover what must be exact:
+#   - geometry: every plate face is struck exactly once (the whole plate
+#     sits inside the gating wedge/radius at this pose);
+#   - the vectorized and scalar strike paths agree (strike arrays exactly,
+#     kinetics arrays to 1e-12, per the plume_unit_test_04 convention);
+#   - internal consistency: the pipeline loads match the analytic
+#     PyRPOD-approximation chain of tests/plume/plume_impingement_utils
+#     (same SimplifiedGasKinetics field + Shen/Maxwellian wall model at the
+#     true incidence angle) to <2% -- the only difference is the hit test's
+#     legacy 3.14-based positional theta feeding the field evaluation.
+#
+# The pipeline-vs-reference gap itself is QUANTITATIVE DOCUMENTATION, not a
+# hard tolerance gate: the Maxwellian chain is an engineering approximation
+# of Cai's exact solution, and the deliverable is the measured gap. Max and
+# mean relative errors (restricted to faces where the reference magnitude
+# is >= 5% of its peak, as in the error summaries) are printed and appended
+# to tests/plume/output/cai2016_pipeline_error_summary.md.
+#
+# Run:  python -m pytest rpod/rpod_integration_test_07.py -s   (from tests/)
+
+import sys
+import time
+import unittest
+from pathlib import Path
+
+import numpy as np
+
+_TESTS_DIR = Path(__file__).resolve().parents[1]
+if str(_TESTS_DIR / 'plume') not in sys.path:
+    sys.path.insert(0, str(_TESTS_DIR / 'plume'))
+if str(_TESTS_DIR.parent) not in sys.path:  # repo root for direct runs
+    sys.path.insert(0, str(_TESTS_DIR.parent))
+
+import plume_impingement_utils as piu  # noqa: E402
+from pyrpod.mission import MissionEnvironment  # noqa: E402
+from pyrpod.plume import CaiImpingement2016 as cai  # noqa: E402
+from pyrpod.plume.PlumeStrikeCalculator import (  # noqa: E402
+    _compute_plume_strikes_scalar,
+    compute_face_centroids,
+    compute_plume_strikes,
+)
+from pyrpod.rpod import JetFiringHistory, PlumeStrikeEstimationStudy  # noqa: E402
+from pyrpod.vehicle import TargetVehicle, VisitingVehicle  # noqa: E402
+
+CASE_DIR = '../case/plume/plume_inclined_plate/'
+SUMMARY_PATH = _TESTS_DIR / 'plume' / 'output' / 'Cai2016' / \
+    'cai2016_pipeline_error_summary.md'
+
+
+def face_areas(vectors):
+    v0, v1, v2 = vectors[:, 0], vectors[:, 1], vectors[:, 2]
+    return 0.5 * np.linalg.norm(np.cross(v1 - v0, v2 - v0), axis=1)
+
+
+class InclinedPlateVerificationChecks(unittest.TestCase):
+
+    def test_pipeline_vs_cai2016_reference(self):
+        # 1. Set up (driver pattern of rpod_integration_test_05)
+        jfh = JetFiringHistory.JetFiringHistory(CASE_DIR)
+        jfh.read_jfh()
+
+        tv = TargetVehicle.TargetVehicle(CASE_DIR)
+        tv.set_stl()
+
+        vv = VisitingVehicle.VisitingVehicle(CASE_DIR)
+        vv.set_thruster_config()
+        vv.set_thruster_metrics()
+
+        me = MissionEnvironment.MissionEnvironment(CASE_DIR)
+
+        study = PlumeStrikeEstimationStudy.PlumeStrikeEstimationStudy(me)
+        study.study_init(jfh, tv, vv)
+
+        # 2. Execute the full pipeline (writes VTK to the case results dir)
+        t0 = time.perf_counter()
+        firing_data = study.jfh_plume_strikes()
+        t_pipeline = time.perf_counter() - t0
+
+        self.assertEqual(list(firing_data.keys()), ['1'])
+        result = firing_data['1']
+
+        target = tv.mesh
+        n_faces = len(target.vectors)
+        centroids = compute_face_centroids(target.vectors)
+        normals = target.get_unit_normals()
+
+        # 3. Geometry: the whole plate lies inside the gating wedge/radius
+        # at the paper pose, so every face must be struck exactly once.
+        np.testing.assert_array_equal(result['strikes'], np.ones(n_faces))
+
+        # 4. Vectorized and scalar paths must agree (shared incidence fix).
+        step = {'thrusters': jfh.JFH[0]['thrusters'],
+                'xyz': np.array(jfh.JFH[0]['xyz']),
+                'dcm': np.array(jfh.JFH[0]['dcm']),
+                't': float(jfh.JFH[0]['t'])}
+        vec = compute_plume_strikes(target, normals, vv, step, me,
+                                    face_centroids=centroids)
+        scal = _compute_plume_strikes_scalar(target, normals, vv, step, me)
+        np.testing.assert_array_equal(vec['strikes'], scal['strikes'])
+        for key in ('pressures', 'shear_stress', 'heat_flux_rate'):
+            self.assertTrue(np.allclose(vec[key], scal[key],
+                                        rtol=1e-12, atol=1e-12),
+                            msg=f'{key}: scalar vs vectorized differ')
+
+        # 5. Convert to the paper's coefficients. Thruster at the origin
+        # firing +X, so centroid coordinates are the paper's (X, Y, Z).
+        Cp_pipe = result['pressures'] / piu.Q_DYN
+        Csh_pipe = result['shear_stress'] / piu.Q_DYN
+        Cq_pipe = result['heat_flux_rate'] / piu.Q_DYN_HEAT
+        # firing time is 1 s, so the load equals the rate
+        self.assertTrue(np.allclose(result['heat_flux_load'],
+                                    result['heat_flux_rate']))
+
+        # 6. Exact reference at the face centroids.
+        ref = cai.surface_coefficients(
+            centroids[:, 0], centroids[:, 1], centroids[:, 2],
+            piu.S_0, piu.ALPHA_0, piu.EPS, piu.R_0)
+        ref_shear = np.hypot(ref['Cf1_d'], ref['Cf2_d'])
+
+        # 7. Internal consistency vs the Phase-1 analytic chain on a face
+        # subsample (every 97th face covers the plate quasi-uniformly).
+        # Denominators are floored at 5% of the subsample peak: the
+        # Maxwellian heat flux changes sign on the plate (adiabatic-wall
+        # crossover), so a purely relative test would divide by ~0 there
+        # while the absolute agreement stays tight.
+        sub = np.arange(0, n_faces, 97)
+        chain = np.array([piu.chain_point_loads(*centroids[i]) for i in sub])
+        for pipe_vals, chain_vals, name in [
+                (result['pressures'][sub], chain[:, 0], 'pressure'),
+                (result['shear_stress'][sub], chain[:, 1], 'shear'),
+                (result['heat_flux_rate'][sub], chain[:, 2], 'heat flux')]:
+            scale = np.maximum(np.abs(chain_vals),
+                               0.05 * np.max(np.abs(chain_vals)))
+            rel = np.abs(pipe_vals - chain_vals) / scale
+            self.assertLess(np.max(rel), 2e-2,
+                            msg=f'pipeline diverged from analytic chain '
+                                f'({name}): max rel {np.max(rel):.3g}')
+
+        # 8. Quantitative documentation of the pipeline-vs-reference gap.
+        areas = face_areas(target.vectors)
+        rows = []
+        for name, pipe, reference in [
+                ('Cp,d', Cp_pipe, ref['Cp_d']),
+                ('|Cf,d|', Csh_pipe, ref_shear),
+                ('Cq,d', Cq_pipe, ref['Cq_d'])]:
+            mask = piu.significant_mask(reference)
+            rel = np.abs(pipe[mask] - reference[mask]) / np.abs(reference[mask])
+            rows.append((name, float(np.max(rel)), float(np.mean(rel)),
+                         float(np.sum(pipe * areas) / np.sum(areas)),
+                         float(np.sum(reference * areas) / np.sum(areas))))
+            print(f'[cai2016] {name}: max rel err {np.max(rel):.3f}, '
+                  f'mean rel err {np.mean(rel):.3f} '
+                  f'(over {mask.sum()}/{n_faces} significant faces)')
+        print(f'[cai2016] pipeline wall time: {t_pipeline:.1f} s '
+              f'({n_faces} faces, 1 firing)')
+
+        SUMMARY_PATH.parent.mkdir(parents=True, exist_ok=True)
+        with open(SUMMARY_PATH, 'w', encoding='utf-8', newline='') as fh:
+            fh.write('# Cai 2016 pipeline error summary '
+                     '(strike pipeline vs exact reference)\n\n')
+            fh.write('Written by tests/rpod/rpod_integration_test_07.py: '
+                     'face-by-face comparison of the '
+                     'PlumeStrikeEstimationStudy loads (Simplified '
+                     'kinetics + Maxwellian wall model at the true '
+                     'incidence angle) against '
+                     'pyrpod/plume/CaiImpingement2016.py at the paper '
+                     f'conditions; {n_faces} faces, pipeline wall time '
+                     f'{t_pipeline:.1f} s.\n\n')
+            fh.write('| quantity | max_rel_err | mean_rel_err | '
+                     'plate avg (pipeline) | plate avg (reference) |\n')
+            fh.write('|---|---|---|---|---|\n')
+            for name, mx, mn, avg_p, avg_r in rows:
+                fh.write(f'| {name} | {mx:.4g} | {mn:.4g} | {avg_p:.4g} | '
+                         f'{avg_r:.4g} |\n')
+            fh.write('\nRelative errors restricted to faces with '
+                     '|reference| >= 5% of its peak (the same near-zero '
+                     'caveat as the other summaries). The gap is the '
+                     'documented accuracy of the Maxwellian engineering '
+                     'chain vs the exact collisionless solution -- not a '
+                     'regression gate.\n')
+        print(f'[cai2016] wrote {SUMMARY_PATH}')
+
+        # Loose envelope so a future regression that breaks the chain
+        # entirely (e.g. reverting to positional theta) fails loudly:
+        # with the orientation-blind bug, mean Cp error was ~3x larger.
+        self.assertLess(rows[0][2], 0.15,
+                        msg='mean Cp error vs reference far above the '
+                            'documented Maxwellian-chain gap')
+
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/tests/rpod/rpod_verification_test_06.py b/tests/rpod/rpod_verification_test_06.py
new file mode 100644
index 0000000..9693006
--- /dev/null
+++ b/tests/rpod/rpod_verification_test_06.py
@@ -0,0 +1,398 @@
+# ========================
+# PyRPOD: tests/rpod/rpod_verification_test_06.py
+# ========================
+# Cai 2016 flat-plate SWEEP verification: the swept analog of
+# rpod_integration_test_07. Runs the 95-firing sweep JFH of
+# case/plume/plume_flat_plate_sweep (a flat alpha0 = 0 reframing of the
+# paper geometry; VV on arcs of radius L about the stationary plate,
+# thruster aimed at the plate center; 19 approach angles alpha = -90..90 deg
+# x 5 stand-off distances L/D in {2,4,6,8,10}) through the strike pipeline's
+# per-firing core (compute_plume_strikes -- the same function
+# PlumeStrikeEstimationStudy calls per firing), reduces each pose to the
+# Eq.-15 plate-averaged coefficients, and compares them against the exact
+# reference (pyrpod/plume/CaiImpingement2016.py). The 60 deg inclined sweep
+# lives in the sibling case plume_inclined_plate_sweep (driven by the study
+# script); the reframing is physics-invariant, so both give identical
+# coefficients -- flat just reads more cleanly in ParaView.
+#
+# This is the pytest promotion of the assertion-relevant core of
+# scripts/inclined_plate_sweep_study.py; that script is kept intact as the
+# full-artifact generator (CSV, coefficient/peak plots, per-pose VTK +
+# ParaView collections). Only the invariants live here -- no plots/CSV.
+# Per-pose strike VTK (one .vtu per pose + ParaView .pvd collections, for
+# visual inspection) is OPT-IN: set the env var PYRPOD_SWEEP_VTK=1 to write
+# them to the case's results/sweep/ (gitignored); the default run is lean.
+#
+# Hard gates (a paper-frame convention error breaks these as O(1)):
+#   - the sweep JFH has exactly len(ALPHAS) x len(L/D) = 95 firings;
+#   - mirror symmetry: results in +/-alpha match to <1e-5 relative (the
+#     JFH stores DCMs to 6 significant digits, so mirrored poses reproduce
+#     to ~1e-6); the edge-on +/-90 deg poses are excluded (their strike
+#     membership is float32-epsilon-arbitrary, see the script docstring);
+#   - CF2 vanishes identically by symmetry (~0 to 1e-4 of the CP scale).
+#
+# The pipeline-vs-reference gap is QUANTITATIVE DOCUMENTATION with a loose
+# regression gate (as in rpod_integration_test_07): the Maxwellian chain
+# is an engineering approximation of Cai's exact solution. Plate-averaged
+# CP/CF1/CQ max/mean relative errors (non-edge-on poses) are printed and
+# written to tests/plume/output/Cai2016/cai2016_sweep_error_summary.md.
+#
+# Run:  python -m pytest rpod/rpod_verification_test_06.py -s   (from tests/)
+# Inspect: PYRPOD_SWEEP_VTK=1 python -m pytest rpod/rpod_verification_test_06.py -s
+#          (writes the per-pose strike .vtu files + sweep_LoD*.pvd)
+
+import os
+import sys
+import time
+import unittest
+from pathlib import Path
+
+import numpy as np
+
+_TESTS_DIR = Path(__file__).resolve().parents[1]
+if str(_TESTS_DIR / 'plume') not in sys.path:
+    sys.path.insert(0, str(_TESTS_DIR / 'plume'))
+if str(_TESTS_DIR.parent) not in sys.path:  # repo root for direct runs
+    sys.path.insert(0, str(_TESTS_DIR.parent))
+
+import plume_impingement_utils as piu  # noqa: E402
+from pyrpod.mission import MissionEnvironment  # noqa: E402
+from pyrpod.plume import CaiImpingement2016 as cai  # noqa: E402
+from pyrpod.plume.PlumeStrikeCalculator import (  # noqa: E402
+    compute_face_centroids,
+    compute_plume_strikes,
+)
+from pyrpod.rpod import JetFiringHistory  # noqa: E402
+from pyrpod.util.stl.stl import convert_stl_to_vtk  # noqa: E402
+from pyrpod.vehicle import TargetVehicle, VisitingVehicle  # noqa: E402
+
+# Dedicated flat-plate sweep case (alpha0 = 0, plate center at the origin):
+# a pure global-frame reframing of the paper geometry so the swept strikes
+# read cleanly in ParaView (flat plate in the X-Y plane, VV swept above it).
+# Its config.ini selects the flat STL (flat_plate_transformed.stl) and the
+# flat sweep JFH (jfh_flat_plate_sweep.A), so no runtime override is needed;
+# the ALPHA0_DEG/PLATE_CENTER constants below match those assets (generated
+# by stl/transform_inclined_plate.py --alpha0-deg 0 --distance 0 and
+# jfh/generate_sweep_jfh.py --alpha0-deg 0 --distance 0). The paper single
+# pose lives in plume_inclined_plate (rpod_integration_test_07); the 60 deg
+# sweep in plume_inclined_plate_sweep (the study script).
+CASE_DIR = '../case/plume/plume_flat_plate_sweep/'
+SUMMARY_PATH = _TESTS_DIR / 'plume' / 'output' / 'Cai2016' / \
+    'cai2016_sweep_error_summary.md'
+
+# Per-pose strike VTK export (opt-in for inspection in ParaView; off by
+# default so the normal pytest run stays lean). Enable by setting the
+# environment variable PYRPOD_SWEEP_VTK=1. Strikes follow the standard RPOD
+# pipeline convention -- one .vtu per firing, numbered by JFH index:
+#   results/strikes/firing-<i>.vtu   (i = 0 .. 94, one pose each)
+#   results/strikes/sweep_LoD<LD>.pvd  (ParaView collections; alpha as time)
+WRITE_VTK = bool(os.environ.get('PYRPOD_SWEEP_VTK'))
+_CASE_ROOT = _TESTS_DIR.parent / 'case' / 'plume' / 'plume_flat_plate_sweep'
+STRIKES_DIR = _CASE_ROOT / 'results' / 'strikes'
+
+# Sweep definition (mirrors scripts/inclined_plate_sweep_study.py).
+PLATE_CENTER = np.array([0.0, 0.0, 0.0])
+ALPHA0_DEG = 0.0                       # the mesh's fixed global tilt
+ALPHAS_DEG = np.arange(-90.0, 90.0 + 1e-9, 10.0)
+L_OVER_D = [2.0, 4.0, 6.0, 8.0, 10.0]
+COEFF_NAMES = ['CP', 'CF1', 'CF2', 'CQ', 'CM', 's_cc']
+
+_A0 = np.deg2rad(ALPHA0_DEG)
+NORMAL_OUT = np.array([-np.sin(_A0), 0.0, np.cos(_A0)])  # toward the VV side
+TANGENT_TAU = np.array([np.cos(_A0), 0.0, np.sin(_A0)])
+TANGENT_S = np.array([0.0, 1.0, 0.0])
+
+
+def face_areas(vectors):
+    v0, v1, v2 = vectors[:, 0], vectors[:, 1], vectors[:, 2]
+    return 0.5 * np.linalg.norm(np.cross(v1 - v0, v2 - v0), axis=1)
+
+
+def pipeline_coeffs(result, centroids, areas, tau_face, thruster_pos,
+                    alpha_deg):
+    """Eq.-15 averaged coefficients, per-face peaks, and the case-frame
+    per-face field arrays (for VTK) for one firing.
+
+    Faithful to scripts/inclined_plate_sweep_study.py's pipeline_row.
+    Signed shear components are decomposed onto the plate (tau, s) axes
+    along the tangential projection of the radial flow direction; alpha > 0
+    poses are sign-flipped (CF1/CM) into the paper convention. The returned
+    face_fields carry the un-flipped case-frame components, matching the
+    actual mesh (as the script's VTK export does).
+    """
+    S_tot = float(np.sum(areas))
+    Cp = result['pressures'] / piu.Q_DYN
+    Csh = result['shear_stress'] / piu.Q_DYN
+    Cq = result['heat_flux_rate'] / piu.Q_DYN_HEAT
+
+    rel = centroids - thruster_pos
+    dist = np.linalg.norm(rel, axis=1)
+    u_hat = rel / dist[:, None]
+    n_in = -NORMAL_OUT
+    cos_inc = u_hat @ n_in
+    t_vec = u_hat - cos_inc[:, None] * n_in
+    t_norm = np.linalg.norm(t_vec, axis=1)
+    safe = t_norm > 1e-12
+    t_hat = np.zeros_like(t_vec)
+    t_hat[safe] = t_vec[safe] / t_norm[safe, None]
+    Cf1 = Csh * (t_hat @ TANGENT_TAU)
+    Cf2 = Csh * (t_hat @ TANGENT_S)
+
+    flip = -1.0 if alpha_deg > 0 else 1.0   # into the paper convention
+    CP = float(np.sum(Cp * areas) / S_tot)
+    CF1 = flip * float(np.sum(Cf1 * areas) / S_tot)
+    CF2 = float(np.sum(Cf2 * areas) / S_tot)
+    CQ = float(np.sum(Cq * areas) / S_tot)
+    CM = flip * float(np.sum(tau_face * Cp * areas) / (2.0 * piu.H_0 * S_tot))
+    s_cc = CM / CP if CP != 0.0 else float('nan')
+
+    face_fields = {
+        'strikes': result['strikes'],
+        'pressure_Pa': result['pressures'],
+        'shear_Pa': result['shear_stress'],
+        'heat_flux_W_m2': result['heat_flux_rate'],
+        'Cp': Cp,
+        'Cshear': Csh,
+        'Cf1_case': Cf1,
+        'Cf2_case': Cf2,
+        'Cq': Cq,
+    }
+    return ({'CP': CP, 'CF1': CF1, 'CF2': CF2, 'CQ': CQ, 'CM': CM,
+             's_cc': s_cc},
+            {'peak_Cp': float(np.max(Cp)), 'peak_Cshear': float(np.max(Csh)),
+             'peak_Cq': float(np.max(Cq)),
+             'n_struck': int(np.count_nonzero(result['strikes']))},
+            face_fields)
+
+
+def write_pose_vtk(target, face_fields, vtk_dir, base_name):
+    """Write one pose's per-face fields to vtk_dir/<base_name>.vtu via the
+    shared convert_stl_to_vtk writer (pyevtk needs C-contiguous float64)."""
+    cell_data = {k: np.ascontiguousarray(v, dtype=np.float64)
+                 for k, v in face_fields.items()}
+    convert_stl_to_vtk(target, vtk_dir, filename=base_name,
+                       cellData=cell_data)
+
+
+def write_pvd(path, entries):
+    """ParaView collection grouping (timestep, relative_vtu_path) entries."""
+    lines = ['<?xml version="1.0"?>',
+             '<VTKFile type="Collection" version="0.1" '
+             'byte_order="LittleEndian">', '  <Collection>']
+    for timestep, rel_file in sorted(entries):
+        lines.append(f'    <DataSet timestep="{timestep:g}" group="" '
+                     f'part="0" file="{rel_file}"/>')
+    lines += ['  </Collection>', '</VTKFile>']
+    path.write_text('\n'.join(lines) + '\n', encoding='utf-8')
+
+
+def reference_rows():
+    """Exact Eq.-15 coefficients per (|alpha|, L), cached (mirror-invariant)."""
+    cache = {}
+    for L in L_OVER_D:
+        for abs_alpha in sorted({abs(a) for a in ALPHAS_DEG}):
+            alpha_paper = np.deg2rad(90.0 - abs_alpha)
+            cache[(abs_alpha, L)] = cai.averaged_coefficients(
+                piu.S_0, alpha_paper, piu.EPS, piu.R_0, L, piu.W_0, piu.H_0)
+    return cache
+
+
+def check_mirror_symmetry(rows):
+    """Results must be mirror-symmetric in +/-alpha (paper convention).
+
+    The +/-90 deg poses are excluded: their strike membership comes from
+    float32-epsilon signs in the facing test, which are not mirrored.
+    CF2 is checked separately -- it vanishes identically by symmetry, so
+    normalizing its asymmetry by its own (noise) scale is meaningless.
+    """
+    worst = 0.0
+    for L in L_OVER_D:
+        by_alpha = {r['alpha_deg']: r for r in rows if r['L_over_D'] == L
+                    and abs(r['alpha_deg']) < 90.0}
+        cp_scale = max(abs(r['CP_pipe']) for r in by_alpha.values())
+        # tolerance covers the triangulation's O(h^2) s-asymmetry (the
+        # cell-diagonal split is not mirror-invariant)
+        assert max(abs(r['CF2_pipe']) for r in by_alpha.values()) \
+            < 1e-4 * cp_scale, f'CF2 not ~0 at L/D={L}'
+        for a in ALPHAS_DEG[(ALPHAS_DEG > 0) & (ALPHAS_DEG < 90.0)]:
+            for name in ('CP', 'CF1', 'CQ', 'CM'):
+                lo, hi = by_alpha[-a][f'{name}_pipe'], by_alpha[a][f'{name}_pipe']
+                scale = max(abs(v) for r in by_alpha.values()
+                            for v in [r[f'{name}_pipe']])
+                scale = max(scale, 1e-6 * cp_scale)
+                worst = max(worst, abs(hi - lo) / scale)
+    # tolerance: the JFH file stores DCMs to 6 significant digits (and
+    # positions to 9), so mirrored poses reproduce to ~1e-6 relative;
+    # a convention error would show up as O(1).
+    assert worst < 1e-5, f'mirror symmetry violated: {worst:.3g}'
+    return worst
+
+
+def reference_envelope(rows):
+    """Plate-averaged pipeline-vs-reference relative error over the
+    non-edge-on poses (|alpha| < 90). Denominators are floored at 5% of
+    each coefficient's own reference peak so the near-zero angles do not
+    divide by ~0 (the significant_mask convention). Returns
+    {name: (max_rel, mean_rel, n_poses)} for CP/CF1/CQ."""
+    sub = [r for r in rows if abs(r['alpha_deg']) < 90.0]
+    out = {}
+    for name in ('CP', 'CF1', 'CQ'):
+        pipe = np.array([r[f'{name}_pipe'] for r in sub])
+        ref = np.array([r[f'{name}_ref'] for r in sub])
+        scale = np.maximum(np.abs(ref), 0.05 * np.max(np.abs(ref)))
+        rel = np.abs(pipe - ref) / scale
+        out[name] = (float(np.max(rel)), float(np.mean(rel)), len(sub))
+    return out
+
+
+class InclinedPlateSweepVerification(unittest.TestCase):
+
+    def test_sweep_vs_cai2016_reference(self):
+        # 1. Set up the flat-sweep case; its config.ini already selects the
+        # flat STL + 95-firing angle x distance JFH, so no override is needed.
+        jfh = JetFiringHistory.JetFiringHistory(CASE_DIR)
+        jfh.read_jfh()
+
+        tv = TargetVehicle.TargetVehicle(CASE_DIR)
+        tv.set_stl()
+
+        vv = VisitingVehicle.VisitingVehicle(CASE_DIR)
+        vv.set_thruster_config()
+        vv.set_thruster_metrics()
+
+        me = MissionEnvironment.MissionEnvironment(CASE_DIR)
+
+        n_firings = len(jfh.JFH)
+        self.assertEqual(
+            n_firings, len(ALPHAS_DEG) * len(L_OVER_D),
+            msg=f'unexpected sweep JFH length {n_firings}; regenerate with '
+                'case/plume/plume_flat_plate_sweep/jfh/generate_sweep_jfh.py '
+                '--alpha0-deg 0 --distance 0 --out jfh_flat_plate_sweep.A')
+
+        # 2. Precompute the plate geometry once (poses share one mesh).
+        target = tv.mesh
+        n_faces = len(target.vectors)
+        normals = target.get_unit_normals()
+        centroids = compute_face_centroids(target.vectors)
+        areas = face_areas(target.vectors)
+        tau_face = (centroids - PLATE_CENTER) @ TANGENT_TAU
+
+        # 3. Exact reference coefficients, cached per (|alpha|, L).
+        t0 = time.perf_counter()
+        ref_cache = reference_rows()
+        t_ref = time.perf_counter() - t0
+
+        # 4. Run every firing through the per-firing pipeline core. When
+        # PYRPOD_SWEEP_VTK is set, also write each pose's per-face strikes
+        # and loads to results/strikes/firing-<i>.vtu (one file per firing,
+        # numbered by JFH index -- the standard RPOD strike convention;
+        # independent poses, no cumulative accumulation).
+        if WRITE_VTK:
+            STRIKES_DIR.mkdir(parents=True, exist_ok=True)
+        pvd_entries = {}   # L/D -> [(alpha_deg, relative vtu path)]
+
+        rows = []
+        t0 = time.perf_counter()
+        for i in range(n_firings):
+            L = L_OVER_D[i // len(ALPHAS_DEG)]
+            alpha_deg = float(ALPHAS_DEG[i % len(ALPHAS_DEG)])
+            step = {'thrusters': jfh.JFH[i]['thrusters'],
+                    'xyz': np.array(jfh.JFH[i]['xyz']),
+                    'dcm': np.array(jfh.JFH[i]['dcm']),
+                    't': float(jfh.JFH[i]['t'])}
+            result = compute_plume_strikes(target, normals, vv, step, me,
+                                           face_centroids=centroids)
+            coeffs, peaks, face_fields = pipeline_coeffs(
+                result, centroids, areas, tau_face, step['xyz'], alpha_deg)
+            ref = ref_cache[(abs(alpha_deg), L)]
+            row = {'alpha_deg': alpha_deg, 'L_over_D': L, **peaks}
+            for name in COEFF_NAMES:
+                row[f'{name}_pipe'] = coeffs[name]
+                row[f'{name}_ref'] = float(ref[name])
+            rows.append(row)
+
+            if WRITE_VTK:
+                base = f'firing-{i}'   # strict JFH-index numbering
+                write_pose_vtk(target, face_fields, STRIKES_DIR, base)
+                pvd_entries.setdefault(L, []).append(
+                    (alpha_deg, f'{base}.vtu'))
+        t_sweep = time.perf_counter() - t0
+
+        if WRITE_VTK:
+            for L, entries in pvd_entries.items():
+                write_pvd(STRIKES_DIR / f'sweep_LoD{int(L):02d}.pvd', entries)
+            print(f'[cai2016-sweep] wrote {n_firings} per-pose strike VTK '
+                  f'files to {STRIKES_DIR} (+ {len(pvd_entries)} '
+                  f'sweep_LoD*.pvd collections)')
+
+        # 5. Report the edge-on poses (excluded from the gates: strike
+        # membership is epsilon-degenerate there, see the script docstring).
+        head_on = {r['L_over_D']: r['CP_pipe'] for r in rows
+                   if r['alpha_deg'] == 0.0}
+        for r in rows:
+            if abs(r['alpha_deg']) == 90.0:
+                print(f"[cai2016-sweep] edge-on alpha={r['alpha_deg']:+.0f}, "
+                      f"L/D={r['L_over_D']:g}: {r['n_struck']} faces pass the "
+                      f"epsilon-degenerate facing test; CP={r['CP_pipe']:.3e} "
+                      f"(head-on {head_on[r['L_over_D']]:.3e})")
+
+        # 6. Hard convention gates.
+        worst = check_mirror_symmetry(rows)
+        self.assertLess(worst, 1e-5,
+                        msg=f'mirror symmetry violated: {worst:.3g}')
+        print(f'[cai2016-sweep] mirror-symmetry worst normalized asymmetry '
+              f'{worst:.2e}')
+
+        # 7. Quantitative documentation of the pipeline-vs-reference gap.
+        env = reference_envelope(rows)
+        for name in ('CP', 'CF1', 'CQ'):
+            mx, mn, n = env[name]
+            print(f'[cai2016-sweep] {name}: max rel err {mx:.3f}, '
+                  f'mean rel err {mn:.3f} (over {n} non-edge-on poses)')
+        print(f'[cai2016-sweep] timings: sweep {t_sweep:.1f} s '
+              f'({t_sweep / n_firings * 1e3:.0f} ms/firing, {n_faces} faces), '
+              f'reference {t_ref:.1f} s')
+
+        SUMMARY_PATH.parent.mkdir(parents=True, exist_ok=True)
+        with open(SUMMARY_PATH, 'w', encoding='utf-8', newline='') as fh:
+            fh.write('# Cai 2016 inclined-plate sweep error summary '
+                     '(strike pipeline vs exact reference)\n\n')
+            fh.write('Written by tests/rpod/rpod_verification_test_06.py: '
+                     'plate-averaged Eq.-15 coefficients from the '
+                     'PlumeStrikeEstimationStudy per-firing core '
+                     '(compute_plume_strikes; Simplified kinetics + '
+                     'Maxwellian wall model at the true incidence angle) '
+                     'over the 95-firing angle x distance sweep, compared '
+                     'against pyrpod/plume/CaiImpingement2016.py '
+                     f'(Eq. 15 quadrature). {len(ALPHAS_DEG)} approach '
+                     f'angles x {len(L_OVER_D)} distances, {n_faces} faces, '
+                     f'sweep wall time {t_sweep:.1f} s.\n\n')
+            fh.write(f'Mirror-symmetry worst normalized asymmetry: '
+                     f'{worst:.2e} (gate < 1e-5).\n\n')
+            fh.write('| quantity | max_rel_err | mean_rel_err | poses |\n')
+            fh.write('|---|---|---|---|\n')
+            for name in ('CP', 'CF1', 'CQ'):
+                mx, mn, n = env[name]
+                fh.write(f'| {name} | {mx:.4g} | {mn:.4g} | {n} |\n')
+            fh.write('\nPlate-averaged relative errors over the non-edge-on '
+                     'poses (|alpha| < 90 deg), denominators floored at 5% '
+                     "of each coefficient's reference peak. The gap is the "
+                     'documented accuracy of the Maxwellian engineering '
+                     'chain vs the exact collisionless solution -- not a '
+                     'regression gate.\n')
+        print(f'[cai2016-sweep] wrote {SUMMARY_PATH}')
+
+        # 8. Loose envelope so a convention regression (e.g. a dropped
+        # paper-frame sign flip) fails loudly while the normal
+        # Maxwellian-chain gap passes. Calibrated from the measured run
+        # (CP tracks reference ~1-3%, CF1 ~5%).
+        self.assertLess(env['CP'][1], 0.08,
+                        msg='mean plate-averaged CP error vs reference far '
+                            'above the documented Maxwellian-chain gap')
+        self.assertLess(env['CF1'][1], 0.15,
+                        msg='mean plate-averaged CF1 error vs reference far '
+                            'above the documented Maxwellian-chain gap')
+
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/tests/rpod/rpod_verification_test_07.py b/tests/rpod/rpod_verification_test_07.py
new file mode 100644
index 0000000..57942ea
--- /dev/null
+++ b/tests/rpod/rpod_verification_test_07.py
@@ -0,0 +1,112 @@
+# ========================
+# PyRPOD: tests/rpod/rpod_verification_test_07.py
+# ========================
+# Cylinder-target sweep SMOKE test: exercises the strike pipeline on a
+# CURVED, closed target (case/plume/plume_cylinder_sweep -- the shared
+# high-res cylinder mesh data/stl/cylinder.stl: 14036 faces, radius 2 m,
+# axis along X in [-7, 0], centroid (-3.5, 0, 0)) instead of a flat plate. The
+# visiting vehicle (single argon thruster) is swept over 19 approach
+# angles x 5 orbit radii (95 firings; jfh_cylinder_sweep.A) about the
+# cylinder centroid, and the full PlumeStrikeEstimationStudy pipeline
+# (jfh_plume_strikes) is run end-to-end.
+#
+# This confirms the case RUNS -- the pipeline loads the cylinder, sweeps
+# every pose, and produces per-firing strikes -- NOT that the loads are
+# physically meaningful (the orbit is a geometric smoke sweep, not a
+# validated impingement scenario). Assertions therefore gate only on the
+# pipeline completing with well-formed per-firing results and the sweep
+# actually illuminating the cylinder.
+#
+# Run:  python -m pytest rpod/rpod_verification_test_07.py -s   (from tests/)
+
+import sys
+import time
+import unittest
+from pathlib import Path
+
+import numpy as np
+
+_TESTS_DIR = Path(__file__).resolve().parents[1]
+if str(_TESTS_DIR.parent) not in sys.path:  # repo root for direct runs
+    sys.path.insert(0, str(_TESTS_DIR.parent))
+
+from pyrpod.mission import MissionEnvironment  # noqa: E402
+from pyrpod.rpod import (  # noqa: E402
+    JetFiringHistory,
+    PlumeStrikeEstimationStudy,
+)
+from pyrpod.vehicle import TargetVehicle, VisitingVehicle  # noqa: E402
+
+CASE_DIR = '../case/plume/plume_cylinder_sweep/'
+N_ANGLES = 19
+N_RADII = 5
+N_FACES = 14036   # data/stl/cylinder.stl (high-res target mesh)
+
+
+class CylinderSweepSmoke(unittest.TestCase):
+
+    def test_cylinder_sweep_runs(self):
+        # 1. Set up the case (minimal driver, as in rpod_integration_test_07);
+        # the case config already selects the cylinder STL + sweep JFH.
+        jfh = JetFiringHistory.JetFiringHistory(CASE_DIR)
+        jfh.read_jfh()
+
+        tv = TargetVehicle.TargetVehicle(CASE_DIR)
+        tv.set_stl()
+
+        vv = VisitingVehicle.VisitingVehicle(CASE_DIR)
+        vv.set_thruster_config()
+        vv.set_thruster_metrics()
+
+        me = MissionEnvironment.MissionEnvironment(CASE_DIR)
+
+        study = PlumeStrikeEstimationStudy.PlumeStrikeEstimationStudy(me)
+        study.study_init(jfh, tv, vv)
+
+        # 2. Geometry sanity: the 95-firing sweep on the cylinder mesh.
+        n_firings = len(jfh.JFH)
+        self.assertEqual(n_firings, N_ANGLES * N_RADII,
+                         msg=f'unexpected sweep length {n_firings}; regenerate '
+                             'with case/plume/plume_cylinder_sweep/jfh/'
+                             'generate_cylinder_sweep_jfh.py')
+        n_faces = len(tv.mesh.vectors)
+        self.assertEqual(n_faces, N_FACES,
+                         msg=f'unexpected target mesh ({n_faces} faces); '
+                             'expected the cylinder_transformed.stl target')
+
+        # 3. Execute the full pipeline end-to-end.
+        t0 = time.perf_counter()
+        firing_data = study.jfh_plume_strikes()
+        dt = time.perf_counter() - t0
+
+        # 4. Every firing produced well-formed per-face results.
+        self.assertEqual(len(firing_data), n_firings)
+        total_strikes = 0
+        for key, cell in firing_data.items():
+            strikes = np.asarray(cell['strikes'])
+            self.assertEqual(strikes.shape, (n_faces,),
+                             msg=f'firing {key}: bad strikes shape')
+            # strikes are a 0/1 membership mask
+            self.assertTrue(np.all((strikes == 0) | (strikes == 1)),
+                            msg=f'firing {key}: strikes not binary')
+            # cumulative strikes never fall below this firing's own strikes
+            cum = np.asarray(cell['cum_strikes'])
+            self.assertTrue(np.all(cum >= strikes),
+                            msg=f'firing {key}: cum_strikes < strikes')
+            total_strikes += int(strikes.sum())
+
+        # 5. The sweep must actually illuminate the cylinder somewhere
+        # (a geometry/aiming regression would strike zero faces everywhere).
+        self.assertGreater(total_strikes, 0,
+                           msg='no faces struck across the whole sweep -- '
+                               'the orbit never illuminates the cylinder')
+
+        peak = max(int(np.asarray(c['strikes']).sum())
+                   for c in firing_data.values())
+        print(f'[cylinder-sweep] {n_firings} firings x {n_faces} faces ran in '
+              f'{dt:.2f} s; {total_strikes} total face-strikes, peak '
+              f'{peak}/{n_faces} struck in a single firing')
+
+
+if __name__ == '__main__':
+    unittest.main()