compressible_ops_kernel.h

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#ifndef __FLUID_COMPRESSIBLE_OPS_KERNEL_H__
#define __FLUID_COMPRESSIBLE_OPS_KERNEL_H__
 
#include <device/device_config.h>
 
template< typename T>
__global__ void compute_max_wave_speed_kernel(T * __restrict__ max_wave_speed,
                                              const T * __restrict__ u,
                                              const T * __restrict__ v,
                                              const T * __restrict__ w,
                                              const T gamma,
                                              const T * __restrict__ p,
                                              const T * __restrict__ rho,
                                              const int n) {
 
  const int idx = blockIdx.x * blockDim.x + threadIdx.x;
  const int str = blockDim.x * gridDim.x;
 
  for (int i = idx; i < n; i += str) {
    T vel_mag = sqrt(u[i]*u[i] + v[i]*v[i] + w[i]*w[i]);
    T sound_speed = sqrt(gamma * p[i] / rho[i]);
    max_wave_speed[i] = vel_mag + sound_speed;
  }
 
}
 
template< typename T>
__global__ void compute_entropy_kernel(T * __restrict__ S,
                                       const T * __restrict__ p,
                                       const T * __restrict__ rho,
                                       const T gamma,
                                       const int n) {
 
  const int idx = blockIdx.x * blockDim.x + threadIdx.x;
  const int str = blockDim.x * gridDim.x;
 
  for (int i = idx; i < n; i += str) {
    // S = 1/(gamma-1) * rho * (log(p) - gamma * log(rho))
    T log_p = log(p[i]);
    T log_rho = log(rho[i]);
    S[i] = (1.0 / (gamma - 1.0)) * rho[i] * (log_p - gamma * log_rho);
  }
 
}
 
template< typename T>
__global__ void update_uvw_kernel(T* __restrict__ u,
                                  T* __restrict__ v,
                                  T* __restrict__ w,
                                  const T* __restrict__ m_x,
                                  const T* __restrict__ m_y,
                                  const T* __restrict__ m_z,
                                  const T* __restrict__ rho,
                                  const int n) {
 
 
  const int idx = blockIdx.x * blockDim.x + threadIdx.x;
  const int str = blockDim.x * gridDim.x;
 
  for (int i = idx; i < n; i += str) {
    u[i] = m_x[i] / rho[i];
    v[i] = m_y[i] / rho[i];
    w[i] = m_z[i] / rho[i];
  }
 
}
 
 
template< typename T>
__global__ void update_mxyz_p_ruvw_kernel(T* __restrict__ m_x,
                                          T* __restrict__ m_y,
                                          T* __restrict__ m_z,
                                          T* __restrict__ p,
                                          T* __restrict__ ruvw,
                                          const T* __restrict__ u,
                                          const T* __restrict__ v,
                                          const T* __restrict__ w,
                                          const T* __restrict__ E,
                                          const T* __restrict__ rho,
                                          const T gamma,
                                          const int n) {
  
  const int idx = blockIdx.x * blockDim.x + threadIdx.x;
  const int str = blockDim.x * gridDim.x;
 
  for (int i = idx; i < n; i += str) {
    m_x[i] = u[i] * rho[i];
    m_y[i] = v[i] * rho[i];
    m_z[i] = w[i] * rho[i];
 
    /* Update p = (gamma - 1) * (E - 0.5 * rho * (u^2 + v^2 + w^2)) */
    const real tmp = 0.5 * rho[i] * (u[i]*u[i] + v[i]*v[i] + w[i]*w[i]);
    p[i] = (gamma - 1.0) * (E[i] - tmp);
    ruvw[i] = tmp;
  }
}
 
#define MAX(a,b) (((a)>(b))?(a):(b))
 
template< typename T>
__global__ void update_e_kernel(T* __restrict__ E,
                                T* __restrict__ p,
                                const T* __restrict__ ruvw,
                                const T gamma,
                                const int n) {
  
  const int idx = blockIdx.x * blockDim.x + threadIdx.x;
  const int str = blockDim.x * gridDim.x;
  
  for (int i = idx; i < n; i += str) {
    /* Ensure pressure is positive */
    p[i] = MAX(p[i], 1e-12);
    /* E = p / (gamma - 1) + 0.5 * rho * (u^2 + v^2 + w^2) */
    E[i] = p[i] * (1.0 / (gamma - 1.0)) + ruvw[i];
  }
}
 
#endif // __FLUID_COMPRESSIBLE_OPS_KERNEL_H__