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added mix gradient

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James McClure 2020-10-05 14:36:26 -04:00
parent c232f076dc
commit 8b095b24ad
1 changed files with 48 additions and 0 deletions
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cpu/MixedGradient.cpp Normal file
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/* Implement Mixed Gradient (Lee et al. JCP 2016)*/
extern "C" void ScaLBL_D3Q19_MixedGradient(int *Map, double *Phi, double *Gradient, int start, int finish, int Np, int Nx, int Ny, int Nz)
{
static int D3Q19[18][3]={{1,0,0},{-1,0,0},{0,1,0},{0,-1,0},{0,0,1},{0,0,-1},
{1,1,0},{-1,-1,0},{1,-1,0},{-1,1,0},
{1,0,1},{-1,0,-1},{1,0,-1},{-1,0,1},
{0,1,1},{0,-1,-1},{0,1,-1},{0,-1,1}};
int i,j,k,n,N;
int np,np2,nm; // neighbors
double v,vp,vp2,vm; // values at neighbors
double grad;
for (int idx=start; idx<finish; idx++){
n = Map[idx]; // layout in regular array
//.......Back out the 3-D indices for node n..............
k = n/(Nx*Ny);
j = (n-Nx*Ny*k)/Nx;
i = n-Nx*Ny*k-Nx*j;
v = Phi[n];
grad = 0.0;
for (int q=0; q<6; q++){
int iqx = D3Q19[q][0];
int iqy = D3Q19[q][1];
int iqz = D3Q19[q][2];
np = (k+iqz)*Nx*Ny + (j+iqy)*Nx + i + iqx;
np2 = (k+2*iqz)*Nx*Ny + (j+2*iqy)*Nx + i + 2*iqx;
nm = (k-iqz)*Nx*Ny + (j-iqy)*Nx + i - iqx;
vp = Phi[np];
vp2 = Phi[np2];
vm = Phi[nm];
grad += 0.25*(5.0*vp1-vp2-3.0*v-vm);
}
for (int q=6; q<18; q++){
int iqx = D3Q19[q][0];
int iqy = D3Q19[q][1];
int iqz = D3Q19[q][2];
np = (k+iqz)*Nx*Ny + (j+iqy)*Nx + i + iqx;
np2 = (k+2*iqz)*Nx*Ny + (j+2*iqy)*Nx + i + 2*iqx;
nm = (k-iqz)*Nx*Ny + (j-iqy)*Nx + i - iqx;
vp = Phi[np];
vp2 = Phi[np2];
vm = Phi[nm];
grad += 0.125*(5.0*vp1-vp2-3.0*v-vm);
}
Gradient[n] = grad;
}
}