embedded3 item 10: the apertured cut-cell wall (AM-wall) — cutwall.rs classification, apertured projection with the compatible wall flux, cut predictor (V_u = αhA, averaged mass fluxes, implicit wall shear, inertia floor), cut load route; sphere MMS CutCell ≤ GhostBinary at n 12/24 (ratio 0.96), loads 9.3/10.7 % at n 24

Co-Authored-By: Claude Fable 5.1 <[email protected]>

crates/specialized/rtx-cfd/src/solvers/incompressible/embedded3/wall.rs

@@ -10,6 +10,7 @@
 
 use super::Grid;
 use super::body::Body;
+use super::cut::CutGeometry;
 use super::step::{Boundaries, Side};
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
@@ -45,7 +46,7 @@ pub(crate) struct StencilNode {
 }
 
 #[derive(Debug, Clone)]
-struct Ghost {
+pub(super) struct Ghost {
     idx: usize,
     x: f64,
     y: f64,
@@ -62,17 +63,20 @@ struct Ghost {
 
 #[derive(Clone)]
 pub struct Mask {
-    grid: Grid,
-    periodic_z: bool,
-    cell_fluid: Vec<bool>,
-    u_kind: Vec<FaceKind>,
-    v_kind: Vec<FaceKind>,
-    w_kind: Vec<FaceKind>,
-    u_ghosts: Vec<Ghost>,
-    v_ghosts: Vec<Ghost>,
-    w_ghosts: Vec<Ghost>,
-    anchor: usize,
-    fluid_cells: usize,
+    pub(super) grid: Grid,
+    pub(super) periodic_z: bool,
+    pub(super) cell_fluid: Vec<bool>,
+    pub(super) u_kind: Vec<FaceKind>,
+    pub(super) v_kind: Vec<FaceKind>,
+    pub(super) w_kind: Vec<FaceKind>,
+    pub(super) u_ghosts: Vec<Ghost>,
+    pub(super) v_ghosts: Vec<Ghost>,
+    pub(super) w_ghosts: Vec<Ghost>,
+    pub(super) anchor: usize,
+    pub(super) fluid_cells: usize,
+    /// The cut geometry of the apertured wall (`WallScheme::CutCell`,
+    /// `cutwall.rs`); `None` on the binary ghost wall.
+    pub(super) cut: Option<CutGeometry>,
 }
 
 /// The z lattice position of a query: the lower plane index, the upper
@@ -479,9 +483,38 @@ impl Mask {
             w_ghosts,
             anchor,
             fluid_cells,
+            cut: None,
         })
     }
 
+    /// The cut geometry (apertured wall only).
+    #[must_use]
+    pub fn cut(&self) -> Option<&CutGeometry> {
+        self.cut.as_ref()
+    }
+    /// Fluid area fraction of a u / v / w face (1 on the binary wall).
+    #[inline]
+    #[must_use]
+    pub fn a_u(&self, idx: usize) -> f64 {
+        self.cut.as_ref().map_or(1.0, |c| c.a_u[idx])
+    }
+    #[inline]
+    #[must_use]
+    pub fn a_v(&self, idx: usize) -> f64 {
+        self.cut.as_ref().map_or(1.0, |c| c.a_v[idx])
+    }
+    #[inline]
+    #[must_use]
+    pub fn a_w(&self, idx: usize) -> f64 {
+        self.cut.as_ref().map_or(1.0, |c| c.a_w[idx])
+    }
+    /// Fluid volume fraction of a cell (1 on the binary wall).
+    #[inline]
+    #[must_use]
+    pub fn vol(&self, idx: usize) -> f64 {
+        self.cut.as_ref().map_or(1.0, |c| c.vol[idx])
+    }
+
     #[inline]
     #[must_use]
     pub fn is_fluid_cell(&self, idx: usize) -> bool {