rtx-cfd legacy GPU: kernel outputs were device-buffer CLONES (every write lost) — the buffers are borrowed mutably now; the Poisson kernels keep boundary Dirichlet values; tests: the advection pulse marched 50 steps, the Jacobi budget 20k, the reduction reference in f64

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

@@ -147,7 +147,7 @@ impl PisoGpuSolver {
     fn copy_to_gpu(&self, flow_field: &FlowField) -> CfdResult<()> {
         let buffers = self
             .gpu_buffers
-            .as_ref()
+            .as_mut()
             .ok_or_else(|| CfdError::gpu_error("GPU buffers not initialized"))?;
 
         // Convert nalgebra matrices to flat vectors
@@ -171,7 +171,7 @@ impl PisoGpuSolver {
     fn copy_from_gpu(&self, flow_field: &mut FlowField) -> CfdResult<()> {
         let buffers = self
             .gpu_buffers
-            .as_ref()
+            .as_mut()
             .ok_or_else(|| CfdError::gpu_error("GPU buffers not initialized"))?;
 
         // Copy from GPU
@@ -271,7 +271,7 @@ impl PisoGpuSolver {
         let (nx, ny) = {
             let buffers = self
                 .gpu_buffers
-                .as_ref()
+                .as_mut()
                 .ok_or_else(|| CfdError::gpu_error("GPU buffers not initialized"))?;
             (buffers.nx, buffers.ny)
         };
@@ -313,7 +313,7 @@ impl PisoGpuSolver {
         let residual_norm = {
             let buffers = self
                 .gpu_buffers
-                .as_ref()
+                .as_mut()
                 .ok_or_else(|| CfdError::gpu_error("GPU buffers not initialized"))?;
             self.matrix_ops_kernel.vector_norm(&buffers.mass_source)?
         };
@@ -464,8 +464,8 @@ impl PisoGpuSolver {
                 .stream()
                 .launch_builder(&func)
                 .arg(&buffers.pressure_correction)
-                .arg(&mut buffers.u_correction.clone())
-                .arg(&mut buffers.v_correction.clone())
+                .arg(&mut buffers.u_correction)
+                .arg(&mut buffers.v_correction)
                 .arg(&correction_factor)
                 .arg(&dx)
                 .arg(&dy)