rtx-cfd: curvilinear collocated PISO on a structured patch (overset A-P0, WIP) — PatchMesh (right-handed s,n; periodic seam with shift; face metrics), patch generators (TFI, skewed annulus, sheared/varying-skew channels), CSR + Jacobi-BiCGSTAB, the Zang–Street–Koseff incremental step with the node-based 9-point L_f, LSQ gradients, explicit and line-implicit-n predictors, adjustPhi; tests: mesh metrics (5 green), operators exact on linear fields incl. the seam (green), sparse (2 green), MMS ladder (Cartesian 16/32: 1.37–1.39x the staggered error, order 0.83; n=64 stalls at a |du/dt| floor 2e-4 — open, tolerance-scaling hypothesis), annulus/Poiseuille not yet run

Co-Authored-By: Claude Fable 5.1 <[email protected]>
Claude-Session: https://claude.ai/code/session_01X2GmJXeQ2njUecEKiJZ1G2

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

@@ -13,6 +13,8 @@ use crate::{CfdConfig, CfdError, CfdResult};
 pub mod ale;
 /// Boundary conditions
 pub mod boundary_conditions;
+/// Collocated PISO on a structured curvilinear patch (the overset patch)
+pub mod curvilinear;
 /// PISO on the fixed grid with an embedded body
 pub mod embedded;
 /// Embedded-body geometry, classification and loads
@@ -32,6 +34,8 @@ pub mod simple;
 /// GPU-accelerated SIMPLE algorithm implementation
 #[cfg(feature = "cuda")]
 pub mod simple_gpu;
+/// CSR matrix + Jacobi-BiCGSTAB for the curvilinear pressure equation
+pub mod sparse_bicgstab;
 
 // Re-export main types
 pub use ale::{
@@ -40,6 +44,10 @@ pub use ale::{
 pub use boundary_conditions::{
     BoundaryCondition, BoundaryConditions, BoundaryLocation, BoundaryType,
 };
+pub use curvilinear::{
+    CurvilinearParameters, CurvilinearPisoSolver, CurvilinearResult, CurvilinearSolverState,
+    NormalDiffusion, Operators, PatchBoundaries, PatchConvection, PatchField, SideBc,
+};
 pub use embedded::{EmbeddedParameters, EmbeddedPisoSolver, EmbeddedResult, EmbeddedSolverState};
 pub use embedded_body::{
     EmbeddedBody, EmbeddedMask, FaceKind, SurfaceForce, SurfaceSample, polygon_interface_velocity,