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Remove terms with kx=0 and ky<=0

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This commit is contained in:
Ian Jauslin
2023-04-25 17:51:14 -04:00
parent 519bb72726
commit d838060265
5 changed files with 50 additions and 37 deletions
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52
src/navier-stokes.c
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@@ -241,12 +241,12 @@ int ns_init_tmps(
unsigned int nthreads
){
// velocity field
*u=calloc(sizeof(_Complex double),(K1+1)*(2*K2+1));
*u=calloc(sizeof(_Complex double),K1*(2*K2+1)+K2);
// allocate tmp vectors for computation
*tmp1=calloc(sizeof(_Complex double),(K1+1)*(2*K2+1));
*tmp2=calloc(sizeof(_Complex double),(K1+1)*(2*K2+1));
*tmp3=calloc(sizeof(_Complex double),(K1+1)*(2*K2+1));
*tmp1=calloc(sizeof(_Complex double),K1*(2*K2+1)+K2);
*tmp2=calloc(sizeof(_Complex double),K1*(2*K2+1)+K2);
*tmp3=calloc(sizeof(_Complex double),K1*(2*K2+1)+K2);
// init threads
fftw_init_threads();
@@ -303,7 +303,7 @@ int copy_u(
){
int i;
for(i=0;i<(K1+1)*(2*K2+1);i++){
for(i=0;i<K1*(2*K2+1)+K2;i++){
u[i]=u0[i];
}
@@ -335,14 +335,14 @@ int ns_step(
ns_rhs(tmp1, u, K1, K2, N1, N2, nu, L, g, fft1, fft2, ifft, irreversible);
// add to output
for(kx=0;kx<=K1;kx++){
for(ky=-K2;ky<=K2;ky++){
for(ky=(kx>0 ? -K2 : 1);ky<=K2;ky++){
tmp3[klookup_sym(kx,ky,K2)]=u[klookup_sym(kx,ky,K2)]+delta/6*tmp1[klookup_sym(kx,ky,K2)];
}
}
// u+h*k1/2
for(kx=0;kx<=K1;kx++){
for(ky=-K2;ky<=K2;ky++){
for(ky=(kx>0 ? -K2 : 1);ky<=K2;ky++){
tmp2[klookup_sym(kx,ky,K2)]=u[klookup_sym(kx,ky,K2)]+delta/2*tmp1[klookup_sym(kx,ky,K2)];
}
}
@@ -350,14 +350,14 @@ int ns_step(
ns_rhs(tmp1, tmp2, K1, K2, N1, N2, nu, L, g, fft1, fft2, ifft, irreversible);
// add to output
for(kx=0;kx<=K1;kx++){
for(ky=-K2;ky<=K2;ky++){
for(ky=(kx>0 ? -K2 : 1);ky<=K2;ky++){
tmp3[klookup_sym(kx,ky,K2)]+=delta/3*tmp1[klookup_sym(kx,ky,K2)];
}
}
// u+h*k2/2
for(kx=0;kx<=K1;kx++){
for(ky=-K2;ky<=K2;ky++){
for(ky=(kx>0 ? -K2 : 1);ky<=K2;ky++){
tmp2[klookup_sym(kx,ky,K2)]=u[klookup_sym(kx,ky,K2)]+delta/2*tmp1[klookup_sym(kx,ky,K2)];
}
}
@@ -365,14 +365,14 @@ int ns_step(
ns_rhs(tmp1, tmp2, K1, K2, N1, N2, nu, L, g, fft1, fft2, ifft, irreversible);
// add to output
for(kx=0;kx<=K1;kx++){
for(ky=-K2;ky<=K2;ky++){
for(ky=(kx>0 ? -K2 : 1);ky<=K2;ky++){
tmp3[klookup_sym(kx,ky,K2)]+=delta/3*tmp1[klookup_sym(kx,ky,K2)];
}
}
// u+h*k3
for(kx=0;kx<=K1;kx++){
for(ky=-K2;ky<=K2;ky++){
for(ky=(kx>0 ? -K2 : 1);ky<=K2;ky++){
tmp2[klookup_sym(kx,ky,K2)]=u[klookup_sym(kx,ky,K2)]+delta*tmp1[klookup_sym(kx,ky,K2)];
}
}
@@ -380,7 +380,7 @@ int ns_step(
ns_rhs(tmp1, tmp2, K1, K2, N1, N2, nu, L, g, fft1, fft2, ifft, irreversible);
// add to output
for(kx=0;kx<=K1;kx++){
for(ky=-K2;ky<=K2;ky++){
for(ky=(kx>0 ? -K2 : 1);ky<=K2;ky++){
u[klookup_sym(kx,ky,K2)]=tmp3[klookup_sym(kx,ky,K2)]+delta/6*tmp1[klookup_sym(kx,ky,K2)];
}
}
@@ -417,14 +417,12 @@ int ns_rhs(
alpha=compute_alpha(u,K1,K2,g,L);
}
for(i=0; i<(K1+1)*(2*K2+1); i++){
for(i=0; i<K1*(2*K2+1)+K2; i++){
out[i]=0;
}
for(kx=0;kx<=K1;kx++){
for(ky=-K2;ky<=K2;ky++){
if(kx!=0 || ky!=0){
out[klookup_sym(kx,ky,K2)]=-4*M_PI*M_PI/L/L*alpha*(kx*kx+ky*ky)*u[klookup_sym(kx,ky,K2)]+g[klookup_sym(kx,ky,K2)]+4*M_PI*M_PI/L/L/sqrt(kx*kx+ky*ky)*ifft.fft[klookup(kx,ky,N1,N2)];
}
for(ky=(kx>0 ? -K2 : 1);ky<=K2;ky++){
out[klookup_sym(kx,ky,K2)]=-4*M_PI*M_PI/L/L*alpha*(kx*kx+ky*ky)*u[klookup_sym(kx,ky,K2)]+g[klookup_sym(kx,ky,K2)]+4*M_PI*M_PI/L/L/sqrt(kx*kx+ky*ky)*ifft.fft[klookup(kx,ky,N1,N2)];
}
}
@@ -610,7 +608,7 @@ int klookup(
return (kx>=0 ? kx : S1+kx)*S2 + (ky>=0 ? ky : S2+ky);
}
// get index for kx,ky in array of size K1,K2 in which only the terms with kx>=0 are stored
// get index for kx,ky in array of size K1,K2 in which only the terms with kx>=0 and if kx=0, ky>0 are stored
int klookup_sym(
int kx,
int ky,
@@ -620,7 +618,14 @@ int klookup_sym(
fprintf(stderr, "bug!: attempting to access a symmetrized vector at kx<0\n Contact Ian at ian.jauslin@rutgers.edu!\n");
exit(-1);
}
return kx*(2*K2+1) + (ky>=0 ? ky : (2*K2+1)+ky);
if (kx==0) {
if (ky<=0){
fprintf(stderr, "bug!: attempting to access a symmetrized vector at kx=0 and ky<=0\n Contact Ian at ian.jauslin@rutgers.edu!\n");
exit(-1);
}
return ky-1;
}
return K2+(kx-1)*(2*K2+1) + (ky>=0 ? ky : (2*K2+1)+ky);
}
// get u_{kx,ky} from a vector u in which only the values for kx>=0 are stored, assuming u_{-k}=u_k^*
@@ -630,5 +635,12 @@ _Complex double getval_sym(
int ky,
int K2
){
return (kx>=0 ? u[klookup_sym(kx,ky,K2)] : conj(u[klookup_sym(-kx,-ky,K2)]));
if(kx>0 || (kx==0 && ky>0)){
return u[klookup_sym(kx,ky,K2)];
}
else if(kx==0 && ky==0){
return 0;
} else {
return conj(u[klookup_sym(-kx,-ky,K2)]);
}
}