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-fsi/tests/fsi2_harness/overset.rs

@@ -310,6 +310,13 @@ impl OversetFluid {
         let params = OversetParameters {
             stall_rounds: 2,
             max_rounds,
+            // `RTX_FSI2O_ROWS`: the overlap depth (patch rows kept non-hole
+            // below the acceptor row; default 4). A deeper overlap widens
+            // the band the acceptors' donors need on a bent patch.
+            overlap_rows: std::env::var("RTX_FSI2O_ROWS")
+                .ok()
+                .and_then(|v| v.parse().ok())
+                .unwrap_or(OversetParameters::default().overlap_rows),
             ..OversetParameters::default()
         };
         let mut solver = OversetPisoSolver::new(background, patch, (nx, ny, h, h), params)?;