63 lines
1.4 KiB
C
63 lines
1.4 KiB
C
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#include "init.h"
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#include "navier-stokes.h"
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#include <stdlib.h>
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#include <math.h>
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// random initial condition
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int init_random (
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_Complex double* u0,
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int K1,
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int K2,
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int seed
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){
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int kx,ky;
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double rescale;
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double x,y;
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srand(seed);
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// random init (set half, then the other half are the conjugates)
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for(kx=0;kx<=K1;kx++){
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for(ky=-K2;ky<=K2;ky++){
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if (kx!=0 || ky>0){
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x=-0.5+((double) rand())/RAND_MAX;
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y=-0.5+((double) rand())/RAND_MAX;
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u0[klookup(kx,ky,2*K1+1,2*K2+1)]=x+y*I;
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u0[klookup(-kx,-ky,2*K1+1,2*K2+1)]=conj(u0[klookup(kx,ky,2*K1+1,2*K2+1)]);
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}
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}
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}
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// rescale to match with Gallavotti's initialization
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rescale=0;
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for(kx=-K1;kx<=K1;kx++){
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for(ky=-K2;ky<=K2;ky++){
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rescale=rescale+((__real__ u0[klookup(kx,ky,2*K1+1,2*K2+1)])*(__real__ u0[klookup(kx,ky,2*K1+1,2*K2+1)])+(__imag__ u0[klookup(kx,ky,2*K1+1,2*K2+1)])*(__imag__ u0[klookup(kx,ky,2*K1+1,2*K2+1)]))*(kx*kx+ky*ky);
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}
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}
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for(kx=-K1;kx<=K1;kx++){
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for(ky=-K2;ky<=K2;ky++){
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u0[klookup(kx,ky,2*K1+1,2*K2+1)]=u0[klookup(kx,ky,2*K1+1,2*K2+1)]*sqrt(1.54511597324389e+02/rescale);
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}
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}
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return 0;
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}
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// Gaussian initial condition
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int init_gaussian (
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_Complex double* u0,
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int K1,
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int K2
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){
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int kx,ky;
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for(kx=-K1;kx<=K1;kx++){
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for(ky=-K2;ky<=K2;ky++){
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u0[klookup(kx,ky,2*K1+1,2*K2+1)]=(kx*kx+ky*ky)*exp(-(kx*kx+ky*ky));
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}
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}
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return 0;
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}
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