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Commit 8f6c887a authored by Cristian Lalescu's avatar Cristian Lalescu
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implement time stepping scheme

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src/fluid_solver.cpp
+ 101
− 14
View file @ 8f6c887a
......@@ -20,6 +20,7 @@
#include <cassert>
#include <cmath>
#include "fluid_solver.hpp"
#include "fftw_tools.hpp"
......@@ -28,7 +29,7 @@
/*****************************************************************************/
/* macros for loops */
/* complex loop */
/* Fourier space loop */
#define CLOOP(expression) \
\
{ \
......@@ -45,6 +46,23 @@
} \
}
/* real space loop */
#define RLOOP(expression) \
\
{ \
int rindex; \
for (int zindex = 0; zindex < this->rd->subsizes[0]; zindex++) \
for (int yindex = 0; yindex < this->rd->subsizes[1]; yindex++) \
{ \
rindex = (zindex * this->rd->sizes[1] + yindex)*this->rd->sizes[2]; \
for (int xindex = 0; xindex < this->rd->subsizes[2]; xindex++) \
{ \
expression; \
rindex++; \
} \
} \
}
/*****************************************************************************/
......@@ -151,8 +169,9 @@ fluid_solver<R>::fluid_solver( \
this->rv[2], this->cv[2], \
MPI_COMM_WORLD, FFTW_ESTIMATE | FFTW_MPI_TRANSPOSED_OUT); \
\
/* wavenumbers etc */ \
/* ``physical'' parameters etc */ \
\
this->nu = 0.01; \
this->dkx = DKX; \
this->dky = DKY; \
this->dkz = DKZ; \
......@@ -257,26 +276,94 @@ void fluid_solver<R>::omega_nonlin( \
k2 = (this->kx[xindex]*this->kx[xindex] + \
this->ky[yindex]*this->ky[yindex] + \
this->kz[zindex]*this->kz[zindex]); \
this->cu[cindex*3 + 0][0] = (this->ky[yindex]*this->cv[src][cindex*3+2][1] - this->kz[zindex]*this->cv[src][cindex*3+1][1]) / k2; \
this->cu[cindex*3 + 1][0] = (this->kz[zindex]*this->cv[src][cindex*3+0][1] - this->kx[xindex]*this->cv[src][cindex*3+2][1]) / k2; \
this->cu[cindex*3 + 2][0] = (this->kx[xindex]*this->cv[src][cindex*3+1][1] - this->ky[yindex]*this->cv[src][cindex*3+0][1]) / k2; \
this->cu[cindex*3 + 0][1] = (this->ky[yindex]*this->cv[src][cindex*3+2][0] - this->kz[zindex]*this->cv[src][cindex*3+1][0]) / k2; \
this->cu[cindex*3 + 1][1] = (this->kz[zindex]*this->cv[src][cindex*3+0][0] - this->kx[xindex]*this->cv[src][cindex*3+2][0]) / k2; \
this->cu[cindex*3 + 2][1] = (this->kx[xindex]*this->cv[src][cindex*3+1][0] - this->ky[yindex]*this->cv[src][cindex*3+0][0]) / k2; \
this->cu[cindex*3+0][0] = (this->ky[yindex]*this->cv[src][cindex*3+2][1] - this->kz[zindex]*this->cv[src][cindex*3+1][1]) / k2; \
this->cu[cindex*3+1][0] = (this->kz[zindex]*this->cv[src][cindex*3+0][1] - this->kx[xindex]*this->cv[src][cindex*3+2][1]) / k2; \
this->cu[cindex*3+2][0] = (this->kx[xindex]*this->cv[src][cindex*3+1][1] - this->ky[yindex]*this->cv[src][cindex*3+0][1]) / k2; \
this->cu[cindex*3+0][1] = (this->ky[yindex]*this->cv[src][cindex*3+2][0] - this->kz[zindex]*this->cv[src][cindex*3+1][0]) / k2; \
this->cu[cindex*3+1][1] = (this->kz[zindex]*this->cv[src][cindex*3+0][0] - this->kx[xindex]*this->cv[src][cindex*3+2][0]) / k2; \
this->cu[cindex*3+2][1] = (this->kx[xindex]*this->cv[src][cindex*3+1][0] - this->ky[yindex]*this->cv[src][cindex*3+0][0]) / k2; \
); \
/* $\imath k \times DFT(u \times \omega)$ */ \
/* get fields from Fourier space to real space */ \
FFTW(execute)(*((FFTW(plan)*)this->r2c_vorticity)); \
FFTW(execute)(*((FFTW(plan)*)this->c2r_velocity )); \
FFTW(execute)(*((FFTW(plan)*)this->vc2r[src])); \
/* compute cross product $u \times \omega$, and normalize */ \
R tmpx0, tmpy0, tmpz0; \
RLOOP ( \
tmpx0 = (this->ru[rindex*3+1]*this->rv[src][rindex*3+2] - this->ru[rindex*3+2]*this->rv[src][rindex*3+1]); \
tmpy0 = (this->ru[rindex*3+2]*this->rv[src][rindex*3+0] - this->ru[rindex*3+0]*this->rv[src][rindex*3+2]); \
tmpz0 = (this->ru[rindex*3+0]*this->rv[src][rindex*3+1] - this->ru[rindex*3+1]*this->rv[src][rindex*3+0]); \
this->ru[rindex*3+0] = tmpx0 / (this->rd->full_size / 3); \
this->ru[rindex*3+1] = tmpy0 / (this->rd->full_size / 3); \
this->ru[rindex*3+2] = tmpz0 / (this->rd->full_size / 3); \
); \
/* go back to Fourier space */ \
FFTW(execute)(*((FFTW(plan)*)this->r2c_velocity )); \
/* compute cross product into vr */ \
/* get cross product back into Fourier space */ \
FFTW(execute)(*((FFTW(plan)*)this->c2r_velocity)); \
/* dealiasing */ \
/* $\imath k \times DFT(u \times \omega)$ */ \
R tmpx1, tmpy1, tmpz1; \
CLOOP( \
tmpx0 = (this->ky[yindex]*this->cu[cindex*3+2][1] - this->kz[zindex]*this->cu[cindex*3+1][1]); \
tmpy0 = (this->kz[zindex]*this->cu[cindex*3+0][1] - this->kx[xindex]*this->cu[cindex*3+2][1]); \
tmpz0 = (this->kx[xindex]*this->cu[cindex*3+1][1] - this->ky[yindex]*this->cu[cindex*3+0][1]); \
tmpx1 = (this->ky[yindex]*this->cu[cindex*3+2][0] - this->kz[zindex]*this->cu[cindex*3+1][0]); \
tmpy1 = (this->kz[zindex]*this->cu[cindex*3+0][0] - this->kx[xindex]*this->cu[cindex*3+2][0]); \
tmpz1 = (this->kx[xindex]*this->cu[cindex*3+1][0] - this->ky[yindex]*this->cu[cindex*3+0][0]); \
this->cu[cindex*3+0][0] = tmpx0;\
this->cu[cindex*3+1][0] = tmpy0;\
this->cu[cindex*3+2][0] = tmpz0;\
this->cu[cindex*3+0][1] = tmpx1;\
this->cu[cindex*3+1][1] = tmpy1;\
this->cu[cindex*3+2][1] = tmpz1;\
); \
} \
\
template<> \
void fluid_solver<R>::step(double dt) \
{ \
double k2, factor0, factor1; \
this->omega_nonlin(0); \
CLOOP( \
k2 = (this->kx[xindex]*this->kx[xindex] + \
this->ky[yindex]*this->ky[yindex] + \
this->kz[zindex]*this->kz[zindex]); \
factor0 = exp(-this->nu * k2 * dt); \
this->cv[1][cindex*3+0][0] = (this->cv[0][cindex*3+0][0] + dt*this->cu[cindex*3+0][0])*factor0; \
this->cv[1][cindex*3+1][0] = (this->cv[0][cindex*3+1][0] + dt*this->cu[cindex*3+1][0])*factor0; \
this->cv[1][cindex*3+2][0] = (this->cv[0][cindex*3+2][0] + dt*this->cu[cindex*3+2][0])*factor0; \
this->cv[1][cindex*3+0][1] = (this->cv[0][cindex*3+0][1] + dt*this->cu[cindex*3+0][1])*factor0; \
this->cv[1][cindex*3+1][1] = (this->cv[0][cindex*3+1][1] + dt*this->cu[cindex*3+1][1])*factor0; \
this->cv[1][cindex*3+2][1] = (this->cv[0][cindex*3+2][1] + dt*this->cu[cindex*3+2][1])*factor0; \
); \
\
this->omega_nonlin(1); \
CLOOP( \
k2 = (this->kx[xindex]*this->kx[xindex] + \
this->ky[yindex]*this->ky[yindex] + \
this->kz[zindex]*this->kz[zindex]); \
factor0 = exp(-this->nu * k2 * dt/2); \
factor1 = exp( this->nu * k2 * dt/2); \
this->cv[2][cindex*3+0][0] = (3*this->cv[0][cindex*3+0][0]*factor0 + (this->cv[1][cindex*3+0][0] + dt*this->cu[cindex*3+0][0])*factor1)*0.25; \
this->cv[2][cindex*3+1][0] = (3*this->cv[0][cindex*3+1][0]*factor0 + (this->cv[1][cindex*3+1][0] + dt*this->cu[cindex*3+1][0])*factor1)*0.25; \
this->cv[2][cindex*3+2][0] = (3*this->cv[0][cindex*3+2][0]*factor0 + (this->cv[1][cindex*3+2][0] + dt*this->cu[cindex*3+2][0])*factor1)*0.25; \
this->cv[2][cindex*3+0][1] = (3*this->cv[0][cindex*3+0][1]*factor0 + (this->cv[1][cindex*3+0][1] + dt*this->cu[cindex*3+0][1])*factor1)*0.25; \
this->cv[2][cindex*3+1][1] = (3*this->cv[0][cindex*3+1][1]*factor0 + (this->cv[1][cindex*3+1][1] + dt*this->cu[cindex*3+1][1])*factor1)*0.25; \
this->cv[2][cindex*3+2][1] = (3*this->cv[0][cindex*3+2][1]*factor0 + (this->cv[1][cindex*3+2][1] + dt*this->cu[cindex*3+2][1])*factor1)*0.25; \
); \
\
this->omega_nonlin(2); \
CLOOP( \
k2 = (this->kx[xindex]*this->kx[xindex] + \
this->ky[yindex]*this->ky[yindex] + \
this->kz[zindex]*this->kz[zindex]); \
factor0 = exp(-this->nu * k2 * dt); \
factor1 = exp(-this->nu * k2 * dt/2); \
this->cv[3][cindex*3+0][0] = (this->cv[0][cindex*3+0][0]*factor0 + 2*(this->cv[1][cindex*3+0][0] + dt*this->cu[cindex*3+0][0])*factor1)/3; \
this->cv[3][cindex*3+1][0] = (this->cv[0][cindex*3+1][0]*factor0 + 2*(this->cv[1][cindex*3+1][0] + dt*this->cu[cindex*3+1][0])*factor1)/3; \
this->cv[3][cindex*3+2][0] = (this->cv[0][cindex*3+2][0]*factor0 + 2*(this->cv[1][cindex*3+2][0] + dt*this->cu[cindex*3+2][0])*factor1)/3; \
this->cv[3][cindex*3+0][1] = (this->cv[0][cindex*3+0][1]*factor0 + 2*(this->cv[1][cindex*3+0][1] + dt*this->cu[cindex*3+0][1])*factor1)/3; \
this->cv[3][cindex*3+1][1] = (this->cv[0][cindex*3+1][1]*factor0 + 2*(this->cv[1][cindex*3+1][1] + dt*this->cu[cindex*3+1][1])*factor1)/3; \
this->cv[3][cindex*3+2][1] = (this->cv[0][cindex*3+2][1]*factor0 + 2*(this->cv[1][cindex*3+2][1] + dt*this->cu[cindex*3+2][1])*factor1)/3; \
); \
\
}
/*****************************************************************************/
......
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