mirror of
https://github.com/smyalygames/FiniteVolumeGPU.git
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210 lines
7.3 KiB
Plaintext
210 lines
7.3 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.cu"
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#include "SWECommon.cu"
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#include "limiters.cu"
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#include "fluxes/CentralUpwind.cu"
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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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const int tx = threadIdx.x;
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const int ty = threadIdx.y;
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{
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int j=ty;
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const int l = j + 2; //Skip ghost cells
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for (int i=tx; i<BLOCK_WIDTH+1; i+=BLOCK_WIDTH) {
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const 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 float3 flux = CentralUpwindFlux(Qm, Qp, g_);
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F[0][j][i] = flux.x;
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F[1][j][i] = flux.y;
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F[2][j][i] = flux.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 int tx = threadIdx.x;
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const int ty = threadIdx.y;
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for (int j=ty; j<BLOCK_HEIGHT+1; j+=BLOCK_HEIGHT) {
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const int l = j + 1;
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{
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int i=tx;
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const 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 float3 flux = CentralUpwindFlux(Qm, Qp, g_);
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G[0][j][i] = flux.x;
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G[1][j][i] = flux.z;
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G[2][j][i] = flux.y;
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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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int nx_, int ny_,
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float dx_, float dy_, float dt_,
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float g_,
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float theta_,
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int step_,
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//Input h^n
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float* h0_ptr_, int h0_pitch_,
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float* hu0_ptr_, int hu0_pitch_,
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float* hv0_ptr_, int hv0_pitch_,
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//Output h^{n+1}
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float* h1_ptr_, int h1_pitch_,
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float* hu1_ptr_, int hu1_pitch_,
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float* hv1_ptr_, int hv1_pitch_) {
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//Index of thread within block
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const int tx = threadIdx.x;
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const int ty = threadIdx.y;
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//Index of cell within domain
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const int ti = blockDim.x*blockIdx.x + threadIdx.x + 2; //Skip global ghost cells, i.e., +2
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const int tj = blockDim.y*blockIdx.y + threadIdx.y + 2;
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//Shared memory variables
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__shared__ float Q[3][BLOCK_HEIGHT+4][BLOCK_WIDTH+4];
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//The following slightly wastes memory, but enables us to reuse the
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//funcitons in common.opencl
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__shared__ float Qx[3][BLOCK_HEIGHT+2][BLOCK_WIDTH+2];
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__shared__ float Qy[3][BLOCK_HEIGHT+2][BLOCK_WIDTH+2];
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__shared__ float F[3][BLOCK_HEIGHT+1][BLOCK_WIDTH+1];
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__shared__ float G[3][BLOCK_HEIGHT+1][BLOCK_WIDTH+1];
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//Read into shared memory
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readBlock<BLOCK_WIDTH+4, BLOCK_HEIGHT+4>(h0_ptr_, h0_pitch_, Q[0], nx_+3, ny_+3);
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readBlock<BLOCK_WIDTH+4, BLOCK_HEIGHT+4>(hu0_ptr_, hu0_pitch_, Q[1], nx_+3, ny_+3);
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readBlock<BLOCK_WIDTH+4, BLOCK_HEIGHT+4>(hv0_ptr_, hv0_pitch_, Q[2], nx_+3, ny_+3);
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__syncthreads();
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//Fix boundary conditions
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noFlowBoundary2(Q, nx_, ny_);
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__syncthreads();
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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 int i = tx + 2; //Skip local ghost cells, i.e., +2
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const int j = ty + 2;
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const float h1 = 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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const float hu1 = 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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const float hv1 = 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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float* const h_row = (float*) ((char*) h1_ptr_ + h1_pitch_*tj);
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float* const hu_row = (float*) ((char*) hu1_ptr_ + hu1_pitch_*tj);
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float* const hv_row = (float*) ((char*) hv1_ptr_ + hv1_pitch_*tj);
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if (step_ == 0) {
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//First step of RK2 ODE integrator
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h_row[ti] = h1;
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hu_row[ti] = hu1;
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hv_row[ti] = hv1;
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}
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else if (step_ == 1) {
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//Second step of RK2 ODE integrator
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//First read Q^n
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const float h_a = h_row[ti];
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const float hu_a = hu_row[ti];
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const float hv_a = hv_row[ti];
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//Compute Q^n+1
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const float h_b = 0.5f*(h_a + h1);
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const float hu_b = 0.5f*(hu_a + hu1);
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const float hv_b = 0.5f*(hv_a + hv1);
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//Write to main memory
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h_row[ti] = h_b;
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hu_row[ti] = hu_b;
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hv_row[ti] = hv_b;
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}
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}
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}
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} //extern "C" |