mirror of
https://github.com/smyalygames/FiniteVolumeGPU.git
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239 lines
8.6 KiB
Plaintext
239 lines
8.6 KiB
Plaintext
/*
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This OpenCL kernel implements the Kurganov-Petrova numerical scheme
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for the shallow water equations, described in
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A. Kurganov & Guergana Petrova
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A Second-Order Well-Balanced Positivity Preserving Central-Upwind
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Scheme for the Saint-Venant System Communications in Mathematical
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Sciences, 5 (2007), 133-160.
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Copyright (C) 2016 SINTEF ICT
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "common.h"
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#include "SWECommon.h"
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#include "limiters.h"
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__device__
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void computeFluxF(float Q[3][BLOCK_HEIGHT + 4][BLOCK_WIDTH + 4],
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float Qx[3][BLOCK_HEIGHT + 2][BLOCK_WIDTH + 2],
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float F[3][BLOCK_HEIGHT + 1][BLOCK_WIDTH + 1],
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const float g_) {
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// Index of thread within block
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{
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const unsigned int tx = threadIdx.x;
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const unsigned int ty = threadIdx.y;
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const unsigned int j = ty;
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const unsigned int l = j + 2; // Skip ghost cells
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for (unsigned int i = tx; i < BLOCK_WIDTH + 1; i += BLOCK_WIDTH) {
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const unsigned int k = i + 1;
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// Q at interface from the right and left
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const float3 Qp = make_float3(Q[0][l][k + 1] - 0.5f * Qx[0][j][i + 1],
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Q[1][l][k + 1] - 0.5f * Qx[1][j][i + 1],
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Q[2][l][k + 1] - 0.5f * Qx[2][j][i + 1]);
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const float3 Qm = make_float3(Q[0][l][k] + 0.5f * Qx[0][j][i],
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Q[1][l][k] + 0.5f * Qx[1][j][i],
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Q[2][l][k] + 0.5f * Qx[2][j][i]);
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// Computed flux
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const auto [x, y, z] = CentralUpwindFlux(Qm, Qp, g_);
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F[0][j][i] = x;
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F[1][j][i] = y;
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F[2][j][i] = z;
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}
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}
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}
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__device__
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void computeFluxG(float Q[3][BLOCK_HEIGHT + 4][BLOCK_WIDTH + 4],
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float Qy[3][BLOCK_HEIGHT + 2][BLOCK_WIDTH + 2],
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float G[3][BLOCK_HEIGHT + 1][BLOCK_WIDTH + 1],
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const float g_) {
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// Index of thread within block
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const unsigned int tx = threadIdx.x;
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const unsigned int ty = threadIdx.y;
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for (unsigned int j = ty; j < BLOCK_HEIGHT + 1; j += BLOCK_HEIGHT) {
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{
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const unsigned int l = j + 1;
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const unsigned int i = tx;
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const unsigned int k = i + 2; // Skip ghost cells
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// Q at interface from the right and left
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// Note that we swap hu and hv
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const float3 Qp = make_float3(Q[0][l + 1][k] - 0.5f * Qy[0][j + 1][i],
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Q[2][l + 1][k] - 0.5f * Qy[2][j + 1][i],
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Q[1][l + 1][k] - 0.5f * Qy[1][j + 1][i]);
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const float3 Qm = make_float3(Q[0][l][k] + 0.5f * Qy[0][j][i],
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Q[2][l][k] + 0.5f * Qy[2][j][i],
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Q[1][l][k] + 0.5f * Qy[1][j][i]);
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// Computed flux
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// Note that we swap back
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const auto [x, y, z] = CentralUpwindFlux(Qm, Qp, g_);
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G[0][j][i] = x;
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G[1][j][i] = z;
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G[2][j][i] = y;
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}
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}
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}
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__device__ void minmodSlopeX(float Q[3][BLOCK_HEIGHT + 4][BLOCK_WIDTH + 4],
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float Qx[3][BLOCK_HEIGHT + 2][BLOCK_WIDTH + 2],
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const float theta_) {
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// Reconstruct slopes along x-axis
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for (int p = 0; p < 3; ++p) {
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{
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const unsigned int j = threadIdx.y + 2;
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for (unsigned int i = threadIdx.x + 1; i < BLOCK_WIDTH + 3; i += BLOCK_WIDTH) {
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Qx[p][j - 2][i - 1] = minmodSlope(Q[p][j][i - 1], Q[p][j][i], Q[p][j][i + 1], theta_);
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}
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}
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}
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}
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/**
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* Reconstructs a minmod slope for a whole block along the ordinate
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*/
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__device__ void minmodSlopeY(float Q[3][BLOCK_HEIGHT + 4][BLOCK_WIDTH + 4],
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float Qy[3][BLOCK_HEIGHT + 2][BLOCK_WIDTH + 2],
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const float theta_) {
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//Reconstruct slopes along y-axis
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for (int p = 0; p < 3; ++p) {
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const unsigned int i = threadIdx.x + 2;
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for (unsigned int j = threadIdx.y + 1; j < BLOCK_HEIGHT + 3; j += BLOCK_HEIGHT) {
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{
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Qy[p][j - 1][i - 2] = minmodSlope(Q[p][j - 1][i], Q[p][j][i], Q[p][j + 1][i], theta_);
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}
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}
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}
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}
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/**
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* This unsplit kernel computes the 2D numerical scheme with a TVD RK2 time integration scheme
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*/
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extern "C" {
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__global__ void KP07Kernel(
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const int nx_, const int ny_,
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const float dx_, const float dy_, const float dt_,
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const float g_,
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const float theta_,
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const int step_order_,
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const int boundary_conditions_,
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// Input h^n
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float *h0_ptr_, const int h0_pitch_,
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float *hu0_ptr_, const int hu0_pitch_,
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float *hv0_ptr_, const int hv0_pitch_,
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// Output h^{n+1}
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float *h1_ptr_, const int h1_pitch_,
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float *hu1_ptr_, const int hu1_pitch_,
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float *hv1_ptr_, const int hv1_pitch_,
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// Output CFL
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float *cfl_,
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// Subarea of internal domain to compute
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const int x0 = 0, const int y0 = 0,
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int x1 = 0, int y1 = 0) {
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if (x1 == 0)
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x1 = nx_;
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if (y1 == 0)
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y1 = ny_;
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constexpr unsigned int w = BLOCK_WIDTH;
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constexpr unsigned int h = BLOCK_HEIGHT;
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constexpr unsigned int gc_x = 2;
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constexpr unsigned int gc_y = 2;
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constexpr unsigned int vars = 3;
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// Index of thread within block
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const unsigned int tx = threadIdx.x;
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const unsigned int ty = threadIdx.y;
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// Index of cell within domain
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const unsigned int ti = blockDim.x * blockIdx.x + threadIdx.x + 2; //Skip global ghost cells, i.e., +2
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const unsigned int tj = blockDim.y * blockIdx.y + threadIdx.y + 2;
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// Shared memory variables
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__shared__ float Q[3][h + 4][w + 4];
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__shared__ float Qx[3][h + 2][w + 2];
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__shared__ float Qy[3][h + 2][w + 2];
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__shared__ float F[3][h + 1][w + 1];
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__shared__ float G[3][h + 1][w + 1];
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// Read into shared memory
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readBlock<w, h, gc_x, gc_y, 1, 1>(h0_ptr_, h0_pitch_, Q[0], nx_, ny_, boundary_conditions_, x0, y0, x1, y1);
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readBlock<w, h, gc_x, gc_y, -1, 1>(hu0_ptr_, hu0_pitch_, Q[1], nx_, ny_, boundary_conditions_, x0, y0, x1, y1);
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readBlock<w, h, gc_x, gc_y, 1, -1>(hv0_ptr_, hv0_pitch_, Q[2], nx_, ny_, boundary_conditions_, x0, y0, x1, y1);
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// Reconstruct slopes along x and axis
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minmodSlopeX(Q, Qx, theta_);
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minmodSlopeY(Q, Qy, theta_);
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__syncthreads();
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// Compute fluxes along the x and y axis
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computeFluxF(Q, Qx, F, g_);
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computeFluxG(Q, Qy, G, g_);
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__syncthreads();
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// Sum fluxes and advance in time for all internal cells
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if (ti > 1 && ti < nx_ + 2 && tj > 1 && tj < ny_ + 2) {
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const unsigned int i = tx + 2; // Skip local ghost cells, i.e., +2
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const unsigned int j = ty + 2;
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Q[0][j][i] += (F[0][ty][tx] - F[0][ty][tx + 1]) * dt_ / dx_
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+ (G[0][ty][tx] - G[0][ty + 1][tx]) * dt_ / dy_;
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Q[1][j][i] += (F[1][ty][tx] - F[1][ty][tx + 1]) * dt_ / dx_
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+ (G[1][ty][tx] - G[1][ty + 1][tx]) * dt_ / dy_;
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Q[2][j][i] += (F[2][ty][tx] - F[2][ty][tx + 1]) * dt_ / dx_
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+ (G[2][ty][tx] - G[2][ty + 1][tx]) * dt_ / dy_;
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const auto h_row = reinterpret_cast<float *>(reinterpret_cast<char *>(h1_ptr_) + h1_pitch_ * tj);
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const auto hu_row = reinterpret_cast<float *>(reinterpret_cast<char *>(hu1_ptr_) + hu1_pitch_ * tj);
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auto *const hv_row = reinterpret_cast<float *>(reinterpret_cast<char *>(hv1_ptr_) + hv1_pitch_ * tj);
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if (getOrder(step_order_) == 2 && getStep(step_order_) == 1) {
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// Write to main memory
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h_row[ti] = 0.5f * (h_row[ti] + Q[0][j][i]);
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hu_row[ti] = 0.5f * (hu_row[ti] + Q[1][j][i]);
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hv_row[ti] = 0.5f * (hv_row[ti] + Q[2][j][i]);
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} else {
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h_row[ti] = Q[0][j][i];
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hu_row[ti] = Q[1][j][i];
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hv_row[ti] = Q[2][j][i];
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}
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}
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// Compute the CFL for this block
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if (cfl_ != nullptr) {
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writeCfl<w, h, gc_x, gc_y, vars>(Q, Q[0], nx_, ny_, dx_, dy_, g_, cfl_);
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}
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}
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} // extern "C"
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