embedded3 S2-2a/S2-3: moving bodies on the device (phased tables, host rebuild per step, impose kernel; gate test), the per-span cut wall route, the flag-wake driver and its geometry pre-flight

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

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

@@ -472,6 +472,22 @@ impl Mask {
         Some([p[0] + s[0], p[1] + s[1], p[2] + s[2]])
     }
 
+    /// The cut-cell load route restricted to the cells (and faces) of the
+    /// planes `k0..k1`, divided by the slab's thickness: the load per unit
+    /// span on a body's mid-section.
+    pub fn cut_wall_force_per_span(
+        &self,
+        body: &Body,
+        f: &Field,
+        mu: f64,
+        t: f64,
+        (k0, k1): (usize, usize),
+    ) -> Option<[f64; 3]> {
+        let (p, s) = self.cut_wall_force_parts_in(body, f, mu, t, Some((k0, k1)))?;
+        let lz = (k1 - k0) as f64 * self.grid.dz;
+        Some([(p[0] + s[0]) / lz, (p[1] + s[1]) / lz, (p[2] + s[2]) / lz])
+    }
+
     /// The cut-cell load route split into its pressure and shear parts.
     pub fn cut_wall_force_parts(
         &self,
@@ -479,14 +495,27 @@ impl Mask {
         f: &Field,
         mu: f64,
         t: f64,
+    ) -> Option<([f64; 3], [f64; 3])> {
+        self.cut_wall_force_parts_in(body, f, mu, t, None)
+    }
+
+    fn cut_wall_force_parts_in(
+        &self,
+        body: &Body,
+        f: &Field,
+        mu: f64,
+        t: f64,
+        planes: Option<(usize, usize)>,
     ) -> Option<([f64; 3], [f64; 3])> {
         let cut = self.cut.as_ref()?;
         let g = self.grid;
         let (nx, ny, nz) = (g.nx, g.ny, g.nz);
+        let (k0, k1) = planes.unwrap_or((0, nz));
         let mut pressure = [0.0; 3];
         let mut force = [0.0; 3];
         for (idx, w) in cut.wall.iter().enumerate() {
-            if self.cell_fluid[idx] {
+            let k = g.kji(idx).0;
+            if self.cell_fluid[idx] && k >= k0 && k < k1 {
                 for c in 0..3 {
                     pressure[c] += f.p[idx] * w[c];
                 }
@@ -497,9 +526,9 @@ impl Mask {
         let w_range = if self.periodic_z { 0..nz } else { 1..nz };
         for c in 0..3 {
             let (ir, jr, kr) = match c {
-                0 => (1..nx, 0..ny, 0..nz),
-                1 => (0..nx, 1..ny, 0..nz),
-                _ => (0..nx, 0..ny, w_range.clone()),
+                0 => (1..nx, 0..ny, k0..k1),
+                1 => (0..nx, 1..ny, k0..k1),
+                _ => (0..nx, 0..ny, w_range.start.max(k0)..w_range.end.min(k1)),
             };
             for k in kr {
                 for j in jr.clone() {