rtx-cfd: the cuda feature builds again — the duplicate CudaKernelManager::stream removed, the legacy k-epsilon GPU model (broken since the initial commit) kept out of the build

crates/specialized/rtx-cfd/src/kernels/cuda_simple.rs

@@ -124,11 +124,6 @@ impl CudaKernelManager {
             .ok_or_else(|| CfdError::gpu_error(&format!("Module {} not found", name)))
     }
 
-    /// Get the CUDA stream
-    pub fn stream(&self) -> &Arc<CudaStream> {
-        &self.stream
-    }
-
     /// Perform GPU reduction to compute sum
     pub fn reduce_sum(&self, input: &CudaSlice<f32>) -> CfdResult<f32> {
         let n = input.len();

crates/specialized/rtx-cfd/src/turbulence/mod.rs

@@ -10,7 +10,10 @@
 pub mod k_epsilon;
 /// GPU-accelerated turbulence models
 #[cfg(feature = "cuda")]
-pub mod k_epsilon_gpu;
+// PERF-2 (2026-09-16): the legacy k-epsilon GPU model no longer matches
+// `KEpsilonConstants` and has not compiled since the initial commit; kept out
+// of the `cuda` build until someone needs it.
+// pub mod k_epsilon_gpu;
 pub mod smagorinsky;
 #[cfg(feature = "cuda")]
 pub mod smagorinsky_gpu;
@@ -19,7 +22,7 @@ pub mod wall_functions;
 
 pub use k_epsilon::{KEpsilonConstants, KEpsilonModel, KEpsilonVariant};
 #[cfg(feature = "cuda")]
-pub use k_epsilon_gpu::KEpsilonGpuModel;
+// pub use k_epsilon_gpu::KEpsilonGpuModel;
 pub use smagorinsky::{SmagorinskyConstants, SmagorinskyModel};
 pub use wall_functions::{EnhancedWallTreatment, LogLawWallFunction, WallFunction};