rtx-cfd: cylinder_flag_patch_deformed_from — the warm-started regeneration (P5's cost lever): the previous patch's interior and its outer ring projected onto the new offset polygon as the start, and an IDEMPOTENT build (one Winslow sweep alternating with the ray re-spacing; the P4-0 one-shot is not a fixed point — measured as the interior moving 0.05 h per build at rest), so a base converged as that map's fixed point stays put (9e-11 h at rest) and each build tracks the outline (interior/wall motion 0.99–1.14, worst angle 74.7°, wall row 0.37 h) 4.5× faster than the cold build; the rigid generator untouched (pins pass); fsi2 overset harness: RTX_FSI2O_WARM_SWEEPS with the converged base as the initial patch and the committed step's mesh as each step's warm start

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_march.rs

@@ -119,6 +119,7 @@ pub fn run_march_overset(case: BenchmarkCase, config: &OversetMarchConfig) -> Ov
     }
     // The release time is the fluid's clock (the rigid step count rounds).
     let t_release = fluid.time();
+    fluid.commit_base();
     let (rigid_drag, rigid_lift) = fluid.measure_force();
     println!(
         "  {} OVERSET rigid phase: {rigid_steps} steps (dt {dt_fluid:.3e}) to t = {:.2} s in {:.0} s wall; wall drag {rigid_drag:.2} (rigid-flag reference {:.1}; the overset's own CFD2 at ny = 41: 137.8), lift {rigid_lift:.2}; rounds mean {:.2}",
@@ -286,8 +287,7 @@ pub fn run_march_overset(case: BenchmarkCase, config: &OversetMarchConfig) -> Ov
                 }
                 let (pd, bd, div) = fl.last_defects.get();
                 let (rough, flips, tn_max, tn_mean) = fl.wall_roughness();
-                let (level, wall_flux, wall_area, poly_flux, poly_area) =
-                    fl.level_and_wall_flux();
+                let (level, wall_flux, wall_area, poly_flux, poly_area) = fl.level_and_wall_flux();
                 let area_rate = (poly_area - prev_area.get()) / dt;
                 println!(
                     "    step {step} pass: |d_new − d_candidate| = {residual:.3e}, |d_new| = {:.3e}, nodal Σ|F| {load:.2} ΣF ({fx:+.2}, {fy:+.2}), power {power:+.3e} W/m, wall t_n roughness {rough:.2} ({flips} flips, max {tn_max:.1} mean {tn_mean:.1} Pa), patch p level {level:+.1} Pa, wall net flux {wall_flux:+.3e} m²/s over {wall_area:.3} m (polygon {poly_flux:+.3e}; flag area rate {area_rate:+.3e}), patch mass defect {pd:.2e} bg {bd:.2e} div {div:.1e}, {faces} faces",
@@ -363,6 +363,7 @@ pub fn run_march_overset(case: BenchmarkCase, config: &OversetMarchConfig) -> Ov
         flag_state = new_state;
         committed_nodal = nodal;
         prev_area.set(fluid.borrow().shared.read().unwrap().area());
+        fluid.borrow_mut().commit_base();
         worst_conservation = worst_conservation.max(conservation);
         faces_used = faces;
         let ux = flag_state.displacement[a_dofs[0]];