P6-b design 2: the Robin wall on the patch's Inner side — RobinWall { alpha, datum } with the wall velocity u_s + (t_f − datum)/α (explicit, damped by the wall's own viscous gain μ/(α d)) and the compliant-wall pressure term |S| p'/α implicit in the projection (the added-mass operator in the fluid's own response); Dirichlet bit for bit when off; MMS pin on the skewed annulus (orders 2.46/2.13 at α = 10 and 100 μ/h, the Dirichlet values; a 1e12 wall reproduces Dirichlet to 2e-6); OversetPisoSolver::patch_mut; harness knob RTX_FSI2O_ROBIN_ALPHA with the previous pass's tractions as the datum, printed in the header

Co-Authored-By: Claude Fable 5.1 <[email protected]>
Claude-Session: https://claude.ai/code/session_01YJPeT6WA2e7YvAnS875AHL

crates/specialized/rtx-cfd/src/solvers/incompressible/mod.rs

@@ -49,12 +49,12 @@ pub use boundary_conditions::{
 pub use curvilinear::{
     CurvilinearParameters, CurvilinearPisoSolver, CurvilinearResult, CurvilinearSolverState,
     NormalDiffusion, Operators, PatchBalance, PatchBoundaries, PatchConvection, PatchField,
-    PatchLoad, SideBc, StepGeometry,
+    PatchLoad, RobinWall, SideBc, StepGeometry,
 };
 pub use embedded::{EmbeddedParameters, EmbeddedPisoSolver, EmbeddedResult, EmbeddedSolverState};
 pub use embedded_body::{
-    EmbeddedBody, EmbeddedMask, FaceKind, SurfaceForce, SurfaceSample, polygon_interface_velocity,
-    polygon_signed_distance,
+    polygon_interface_velocity, polygon_signed_distance, EmbeddedBody, EmbeddedMask, FaceKind,
+    SurfaceForce, SurfaceSample,
 };
 pub use flow_field::FlowField;
 pub use overset::{