rtx-cfd: the deformed cylinder–flag build's hull source carries the deformed outline — the cylinder + tip disc alone give the chord under a bent flag's convex side (P5-2 died at tip −35 mm with the patch 4.4 h thick where 6 h was asked, an acceptor's donor on a prescribed face); the death reproduced from the last saved instant by extrapolating the interface (fsi2_overset_probe_death_from_instant, with the failing acceptor's ray geometry and the overlap depths that build) and gone with the fix at every τ; RTX_FSI2O_ROWS; the zero-displacement mesh gate at 1e-5 (the pipeline's), the outline gate 1e-12 unchanged

Co-Authored-By: Claude Fable 5.1 <[email protected]>
Claude-Session: https://claude.ai/code/session_0116sg1Qz1gMv9hdcKP1XUam

crates/specialized/rtx-cfd/src/mesh/patch_gen.rs

@@ -669,7 +669,14 @@ pub fn cylinder_flag_patch_deformed_from(
 ) -> CfdResult<(PatchMesh, (usize, f64))> {
     let (inner, tip) =
         cylinder_flag_outline_deformed(centre, r, t, edges, x_tip_ref, fillet, 3, 16, h, 1.15);
-    let hull_src = hull_source(centre, r, tip.centre, tip.radius, tip.axis);
+    // The hull source carries the deformed outline itself: for a straight
+    // flag the cylinder and the tip disc alone give the flag's surfaces as
+    // the hull's tangents, for a BENT flag they give the chord under the
+    // convex side — measured on FSI2 at tip −35 mm as a patch 4.4 h thick
+    // where 6 h was asked, the acceptors' donors reaching into the fringe
+    // (P5-2's first death).
+    let mut hull_src = hull_source(centre, r, tip.centre, tip.radius, tip.axis);
+    hull_src.extend(inner.iter().copied());
     let start = prev.and_then(|m| {
         (m.ns() == inner.len() && m.nn() == nn).then(|| {
             (0..=nn)