Initial commit

This commit is contained in:
redclawsystems
2026-03-04 00:08:42 +00:00
commit 4d88dc0584
4449 changed files with 1556714 additions and 0 deletions
@@ -0,0 +1,630 @@
//! GPU-accelerated D2Q9 Lattice Boltzmann solver
//!
//! Implementation of the D2Q9 (2D, 9 velocities) LBM scheme on GPU
//! for incompressible flow simulations.
use crate::kernels::CudaKernelManager;
use crate::solvers::BoundaryConditions;
use crate::solvers::incompressible::flow_field::FlowField;
use crate::{CfdConfig, CfdError, CfdResult};
use cudarc::driver::{CudaModule, CudaSlice, LaunchConfig, PushKernelArg};
use nalgebra::Vector2;
use std::sync::Arc;
/// GPU buffers for D2Q9 LBM solver
struct D2Q9GpuBuffers {
/// Distribution functions (9 velocities per cell)
f: CudaSlice<f32>,
/// Temporary distribution functions for streaming
f_temp: CudaSlice<f32>,
/// Equilibrium distributions
f_eq: CudaSlice<f32>,
/// Macroscopic density
density: CudaSlice<f32>,
/// Macroscopic velocity x-component
velocity_x: CudaSlice<f32>,
/// Macroscopic velocity y-component
velocity_y: CudaSlice<f32>,
/// Grid dimensions
nx: usize,
ny: usize,
}
/// GPU-accelerated D2Q9 Lattice Boltzmann solver
pub struct D2Q9GpuSolver {
/// CUDA kernel manager
kernel_manager: Arc<CudaKernelManager>,
/// LBM module with compiled kernels
lbm_module: Option<Arc<CudaModule>>,
/// GPU buffers
gpu_buffers: Option<D2Q9GpuBuffers>,
/// Relaxation parameter
omega: f64,
/// Lattice speed
cs2: f64,
}
impl D2Q9GpuSolver {
/// Create a new D2Q9 GPU solver
pub fn new(config: &CfdConfig) -> CfdResult<Self> {
let kernel_manager = Arc::new(CudaKernelManager::new(config)?);
Ok(Self {
kernel_manager,
lbm_module: None,
gpu_buffers: None,
omega: 1.0, // Will be computed from viscosity
cs2: 1.0 / 3.0, // Speed of sound squared for D2Q9
})
}
/// Initialize solver with flow field
pub fn initialize(&mut self, flow_field: &FlowField, viscosity: f64) -> CfdResult<()> {
// Compute relaxation parameter from viscosity
let dt = 1.0; // LBM time step
let dx = 1.0; // LBM space step
self.omega = 1.0 / (3.0 * viscosity * dt / (dx * dx) + 0.5);
// Load LBM kernels
self.load_lbm_kernels()?;
// Initialize GPU buffers
self.initialize_gpu_buffers(flow_field)?;
Ok(())
}
/// Load and compile LBM kernels
fn load_lbm_kernels(&mut self) -> CfdResult<()> {
// For now, use a placeholder - in real implementation would load PTX
// or compile CUDA kernels for D2Q9 operations
// The module would contain kernels for:
// - Collision step
// - Streaming step
// - Boundary conditions
// - Equilibrium computation
// - Macroscopic variables computation
let module = self.kernel_manager.get_module("lbm_d2q9_kernels")?;
self.lbm_module = Some(module.clone());
Ok(())
}
/// Initialize GPU buffers from flow field
fn initialize_gpu_buffers(&mut self, flow_field: &FlowField) -> CfdResult<()> {
let (nx, ny, _, _) = flow_field.grid_info();
let n_cells = nx * ny;
let n_velocities = 9;
let n_distributions = n_cells * n_velocities;
// Allocate GPU memory
let f = self.kernel_manager.allocate_f32(n_distributions)?;
let f_temp = self.kernel_manager.allocate_f32(n_distributions)?;
let f_eq = self.kernel_manager.allocate_f32(n_distributions)?;
let density = self.kernel_manager.allocate_f32(n_cells)?;
let velocity_x = self.kernel_manager.allocate_f32(n_cells)?;
let velocity_y = self.kernel_manager.allocate_f32(n_cells)?;
// Initialize distributions from flow field
self.initialize_distributions_from_flow(
&f,
&density,
&velocity_x,
&velocity_y,
flow_field,
)?;
self.gpu_buffers = Some(D2Q9GpuBuffers {
f,
f_temp,
f_eq,
density,
velocity_x,
velocity_y,
nx,
ny,
});
Ok(())
}
/// Initialize distributions from flow field data
fn initialize_distributions_from_flow(
&self,
f: &CudaSlice<f32>,
density: &CudaSlice<f32>,
velocity_x: &CudaSlice<f32>,
velocity_y: &CudaSlice<f32>,
flow_field: &FlowField,
) -> CfdResult<()> {
// Copy flow field data to GPU
let (nx, ny, _, _) = flow_field.grid_info();
// Flatten flow field data for GPU transfer
let mut rho_host = Vec::with_capacity(nx * ny);
let mut u_host = Vec::with_capacity(nx * ny);
let mut v_host = Vec::with_capacity(nx * ny);
for j in 0..ny {
for i in 0..nx {
// For incompressible flow, use constant density
rho_host.push(1.0f32);
// Get velocity from FlowField - note the staggered grid
let (u_val, v_val) = flow_field.get_velocity_at(i, j).unwrap_or((0.0, 0.0));
u_host.push(u_val as f32);
v_host.push(v_val as f32);
}
}
// Copy to GPU (htod: host source, device destination - needs mutable)
let density_mut = &mut density.clone();
let velocity_x_mut = &mut velocity_x.clone();
let velocity_y_mut = &mut velocity_y.clone();
self.kernel_manager
.stream()
.memcpy_htod(&rho_host, density_mut)
.map_err(|e| CfdError::gpu_error(&format!("Failed to copy density to GPU: {}", e)))?;
self.kernel_manager
.stream()
.memcpy_htod(&u_host, velocity_x_mut)
.map_err(|e| {
CfdError::gpu_error(&format!("Failed to copy velocity_x to GPU: {}", e))
})?;
self.kernel_manager
.stream()
.memcpy_htod(&v_host, velocity_y_mut)
.map_err(|e| {
CfdError::gpu_error(&format!("Failed to copy velocity_y to GPU: {}", e))
})?;
// Initialize equilibrium distributions on GPU
self.compute_equilibrium_distributions(f, density, velocity_x, velocity_y, nx, ny)?;
Ok(())
}
/// Compute equilibrium distributions on GPU
fn compute_equilibrium_distributions(
&self,
f: &CudaSlice<f32>,
density: &CudaSlice<f32>,
velocity_x: &CudaSlice<f32>,
velocity_y: &CudaSlice<f32>,
nx: usize,
ny: usize,
) -> CfdResult<()> {
let module = self
.lbm_module
.as_ref()
.ok_or_else(|| CfdError::gpu_error("LBM module not loaded"))?;
let func = module.load_function("d2q9_equilibrium_init").map_err(|e| {
CfdError::gpu_error(&format!("Failed to get equilibrium kernel: {}", e))
})?;
let grid_dim_x = (nx as u32 + 15) / 16;
let grid_dim_y = (ny as u32 + 15) / 16;
let config = LaunchConfig {
grid_dim: (grid_dim_x, grid_dim_y, 1),
block_dim: (16, 16, 1),
shared_mem_bytes: 0,
};
unsafe {
self.kernel_manager
.stream()
.launch_builder(&func)
.arg(&mut f.clone())
.arg(density)
.arg(velocity_x)
.arg(velocity_y)
.arg(&(self.cs2 as f32))
.arg(&(nx as i32))
.arg(&(ny as i32))
.launch(config)
.map_err(|e| {
CfdError::gpu_error(&format!("Equilibrium init kernel launch failed: {}", e))
})?;
}
self.kernel_manager.synchronize()?;
Ok(())
}
/// Execute one LBM time step
pub async fn step(&mut self, boundary_conditions: &BoundaryConditions) -> CfdResult<()> {
// Collision step
self.gpu_collision_step()?;
// Streaming step
self.gpu_streaming_step()?;
// Apply boundary conditions
self.gpu_apply_boundaries(boundary_conditions)?;
// Compute macroscopic variables
self.gpu_compute_macroscopic()?;
Ok(())
}
/// GPU-accelerated collision step
fn gpu_collision_step(&self) -> CfdResult<()> {
let buffers = self
.gpu_buffers
.as_ref()
.ok_or_else(|| CfdError::gpu_error("GPU buffers not initialized"))?;
// First compute equilibrium distributions
self.gpu_compute_equilibrium()?;
// Then perform collision: f = f + omega * (f_eq - f)
let module = self
.lbm_module
.as_ref()
.ok_or_else(|| CfdError::gpu_error("LBM module not loaded"))?;
let func = module
.load_function("d2q9_collision")
.map_err(|e| CfdError::gpu_error(&format!("Failed to get collision kernel: {}", e)))?;
let grid_dim_x = (buffers.nx as u32 + 15) / 16;
let grid_dim_y = (buffers.ny as u32 + 15) / 16;
let config = LaunchConfig {
grid_dim: (grid_dim_x, grid_dim_y, 1),
block_dim: (16, 16, 1),
shared_mem_bytes: 0,
};
unsafe {
self.kernel_manager
.stream()
.launch_builder(&func)
.arg(&mut buffers.f.clone())
.arg(&buffers.f_eq)
.arg(&(self.omega as f32))
.arg(&(buffers.nx as i32))
.arg(&(buffers.ny as i32))
.launch(config)
.map_err(|e| {
CfdError::gpu_error(&format!("Collision kernel launch failed: {}", e))
})?;
}
self.kernel_manager.synchronize()?;
Ok(())
}
/// GPU-accelerated streaming step
pub fn gpu_streaming_step(&self) -> CfdResult<()> {
let buffers = self
.gpu_buffers
.as_ref()
.ok_or_else(|| CfdError::gpu_error("GPU buffers not initialized"))?;
let module = self
.lbm_module
.as_ref()
.ok_or_else(|| CfdError::gpu_error("LBM module not loaded"))?;
let func = module
.load_function("d2q9_streaming")
.map_err(|e| CfdError::gpu_error(&format!("Failed to get streaming kernel: {}", e)))?;
let grid_dim_x = (buffers.nx as u32 + 15) / 16;
let grid_dim_y = (buffers.ny as u32 + 15) / 16;
let config = LaunchConfig {
grid_dim: (grid_dim_x, grid_dim_y, 1),
block_dim: (16, 16, 1),
shared_mem_bytes: 0,
};
unsafe {
self.kernel_manager
.stream()
.launch_builder(&func)
.arg(&mut buffers.f_temp.clone())
.arg(&buffers.f)
.arg(&(buffers.nx as i32))
.arg(&(buffers.ny as i32))
.launch(config)
.map_err(|e| {
CfdError::gpu_error(&format!("Streaming kernel launch failed: {}", e))
})?;
}
// Swap buffers: f = f_temp
// In real implementation, would swap buffer pointers
self.kernel_manager.synchronize()?;
Ok(())
}
/// GPU-accelerated macroscopic variable computation
fn gpu_compute_macroscopic(&self) -> CfdResult<()> {
let buffers = self
.gpu_buffers
.as_ref()
.ok_or_else(|| CfdError::gpu_error("GPU buffers not initialized"))?;
let module = self
.lbm_module
.as_ref()
.ok_or_else(|| CfdError::gpu_error("LBM module not loaded"))?;
let func = module.load_function("d2q9_macroscopic").map_err(|e| {
CfdError::gpu_error(&format!("Failed to get macroscopic kernel: {}", e))
})?;
let grid_dim_x = (buffers.nx as u32 + 15) / 16;
let grid_dim_y = (buffers.ny as u32 + 15) / 16;
let config = LaunchConfig {
grid_dim: (grid_dim_x, grid_dim_y, 1),
block_dim: (16, 16, 1),
shared_mem_bytes: 0,
};
unsafe {
self.kernel_manager
.stream()
.launch_builder(&func)
.arg(&mut buffers.density.clone())
.arg(&mut buffers.velocity_x.clone())
.arg(&mut buffers.velocity_y.clone())
.arg(&buffers.f)
.arg(&(buffers.nx as i32))
.arg(&(buffers.ny as i32))
.launch(config)
.map_err(|e| {
CfdError::gpu_error(&format!(
"Macroscopic variables kernel launch failed: {}",
e
))
})?;
}
self.kernel_manager.synchronize()?;
Ok(())
}
/// Compute equilibrium distributions on GPU
fn gpu_compute_equilibrium(&self) -> CfdResult<()> {
let buffers = self
.gpu_buffers
.as_ref()
.ok_or_else(|| CfdError::gpu_error("GPU buffers not initialized"))?;
let module = self
.lbm_module
.as_ref()
.ok_or_else(|| CfdError::gpu_error("LBM module not loaded"))?;
let func = module.load_function("d2q9_equilibrium").map_err(|e| {
CfdError::gpu_error(&format!("Failed to get equilibrium kernel: {}", e))
})?;
let grid_dim_x = (buffers.nx as u32 + 15) / 16;
let grid_dim_y = (buffers.ny as u32 + 15) / 16;
let config = LaunchConfig {
grid_dim: (grid_dim_x, grid_dim_y, 1),
block_dim: (16, 16, 1),
shared_mem_bytes: 0,
};
unsafe {
self.kernel_manager
.stream()
.launch_builder(&func)
.arg(&mut buffers.f_eq.clone())
.arg(&buffers.density)
.arg(&buffers.velocity_x)
.arg(&buffers.velocity_y)
.arg(&(buffers.nx as i32))
.arg(&(buffers.ny as i32))
.launch(config)
.map_err(|e| {
CfdError::gpu_error(&format!("Equilibrium kernel launch failed: {}", e))
})?;
}
self.kernel_manager.synchronize()?;
Ok(())
}
/// GPU-accelerated bounce-back boundary conditions
pub fn gpu_apply_bounce_back_boundaries(&self) -> CfdResult<()> {
let buffers = self
.gpu_buffers
.as_ref()
.ok_or_else(|| CfdError::gpu_error("GPU buffers not initialized"))?;
let module = self
.lbm_module
.as_ref()
.ok_or_else(|| CfdError::gpu_error("LBM module not loaded"))?;
let func = module
.load_function("d2q9_bounce_back_boundaries")
.map_err(|e| CfdError::gpu_error(&format!("Failed to get boundary kernel: {}", e)))?;
let grid_dim_x = (buffers.nx as u32 + 15) / 16;
let grid_dim_y = (buffers.ny as u32 + 15) / 16;
let config = LaunchConfig {
grid_dim: (grid_dim_x, grid_dim_y, 1),
block_dim: (16, 16, 1),
shared_mem_bytes: 0,
};
unsafe {
self.kernel_manager
.stream()
.launch_builder(&func)
.arg(&mut buffers.f.clone())
.arg(&(buffers.nx as i32))
.arg(&(buffers.ny as i32))
.launch(config)
.map_err(|e| {
CfdError::gpu_error(&format!("Boundary kernel launch failed: {}", e))
})?;
}
self.kernel_manager.synchronize()?;
Ok(())
}
/// Complete GPU LBM time step
pub fn gpu_step(&self) -> CfdResult<()> {
self.gpu_collision_step()?;
self.gpu_streaming_step()?;
self.gpu_apply_bounce_back_boundaries()?;
self.gpu_compute_macroscopic()?;
Ok(())
}
/// Initialize flow with uniform velocity
pub fn initialize_uniform_flow(
&mut self,
density: f64,
velocity: Vector2<f64>,
) -> CfdResult<()> {
let buffers = self
.gpu_buffers
.as_ref()
.ok_or_else(|| CfdError::gpu_error("GPU buffers not initialized"))?;
let module = self
.lbm_module
.as_ref()
.ok_or_else(|| CfdError::gpu_error("LBM module not loaded"))?;
let func = module.load_function("d2q9_init_uniform").map_err(|e| {
CfdError::gpu_error(&format!("Failed to get initialization kernel: {}", e))
})?;
let grid_dim_x = (buffers.nx as u32 + 15) / 16;
let grid_dim_y = (buffers.ny as u32 + 15) / 16;
let config = LaunchConfig {
grid_dim: (grid_dim_x, grid_dim_y, 1),
block_dim: (16, 16, 1),
shared_mem_bytes: 0,
};
unsafe {
self.kernel_manager
.stream()
.launch_builder(&func)
.arg(&mut buffers.f.clone())
.arg(&mut buffers.density.clone())
.arg(&mut buffers.velocity_x.clone())
.arg(&mut buffers.velocity_y.clone())
.arg(&(density as f32))
.arg(&(velocity.x as f32))
.arg(&(velocity.y as f32))
.arg(&(buffers.nx as i32))
.arg(&(buffers.ny as i32))
.launch(config)
.map_err(|e| {
CfdError::gpu_error(&format!("Initialization kernel launch failed: {}", e))
})?;
}
self.kernel_manager.synchronize()?;
Ok(())
}
/// Get macroscopic variables at a specific point (copy from GPU)
pub fn get_macroscopic_at(&self, i: usize, j: usize) -> CfdResult<(f64, Vector2<f64>)> {
let buffers = self
.gpu_buffers
.as_ref()
.ok_or_else(|| CfdError::gpu_error("GPU buffers not initialized"))?;
let idx = j * buffers.nx + i;
// Copy single values from GPU
let mut density_val = vec![0.0f32; 1];
let mut vx_val = vec![0.0f32; 1];
let mut vy_val = vec![0.0f32; 1];
self.kernel_manager
.stream()
.memcpy_dtoh(&buffers.density.slice(idx..idx + 1), &mut density_val)
.map_err(|e| CfdError::gpu_error(&format!("Failed to copy density from GPU: {}", e)))?;
self.kernel_manager
.stream()
.memcpy_dtoh(&buffers.velocity_x.slice(idx..idx + 1), &mut vx_val)
.map_err(|e| {
CfdError::gpu_error(&format!("Failed to copy velocity_x from GPU: {}", e))
})?;
self.kernel_manager
.stream()
.memcpy_dtoh(&buffers.velocity_y.slice(idx..idx + 1), &mut vy_val)
.map_err(|e| {
CfdError::gpu_error(&format!("Failed to copy velocity_y from GPU: {}", e))
})?;
self.kernel_manager.synchronize()?;
Ok((
density_val[0] as f64,
Vector2::new(vx_val[0] as f64, vy_val[0] as f64),
))
}
/// Apply boundary conditions
fn gpu_apply_boundaries(&self, _boundary_conditions: &BoundaryConditions) -> CfdResult<()> {
// For now, just apply bounce-back
self.gpu_apply_bounce_back_boundaries()?;
Ok(())
}
/// Update flow field from GPU results
pub fn update_flow_field(&self, flow_field: &mut FlowField) -> CfdResult<()> {
let buffers = self
.gpu_buffers
.as_ref()
.ok_or_else(|| CfdError::gpu_error("GPU buffers not initialized"))?;
let (nx, ny, _, _) = flow_field.grid_info();
let n_cells = nx * ny;
// Copy results back from GPU
let mut density_host = vec![0.0f32; n_cells];
let mut vx_host = vec![0.0f32; n_cells];
let mut vy_host = vec![0.0f32; n_cells];
self.kernel_manager
.stream()
.memcpy_dtoh(&buffers.density, &mut density_host)
.map_err(|e| CfdError::gpu_error(&format!("Failed to copy density from GPU: {}", e)))?;
self.kernel_manager
.stream()
.memcpy_dtoh(&buffers.velocity_x, &mut vx_host)
.map_err(|e| {
CfdError::gpu_error(&format!("Failed to copy velocity_x from GPU: {}", e))
})?;
self.kernel_manager
.stream()
.memcpy_dtoh(&buffers.velocity_y, &mut vy_host)
.map_err(|e| {
CfdError::gpu_error(&format!("Failed to copy velocity_y from GPU: {}", e))
})?;
self.kernel_manager.synchronize()?;
// Update flow field velocities
for j in 0..ny {
for i in 0..nx {
let idx = j * nx + i;
// Note: density is not stored in incompressible FlowField
// Update velocities using set_velocity method
flow_field.set_velocity(i, j, vx_host[idx] as f64, vy_host[idx] as f64)?;
}
}
Ok(())
}
}