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Reversible equation

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This commit is contained in:
Ian Jauslin
2023-04-05 20:33:38 -04:00
parent 75de7e03b7
commit 0bf223bcb9
3 changed files with 87 additions and 29 deletions
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77
src/navier-stokes.c
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@@ -15,6 +15,7 @@ int uk(
double L,
_Complex double* u0,
_Complex double* g,
bool irreversible,
unsigned int print_freq,
unsigned int starting_time,
unsigned int nthreads,
@@ -48,7 +49,7 @@ int uk(
// iterate
for(t=starting_time;t<starting_time+nsteps;t++){
ins_step(u, K1, K2, N1, N2, nu, delta, L, g, fft1, fft2, ifft, tmp1, tmp2, tmp3);
ns_step(u, K1, K2, N1, N2, nu, delta, L, g, fft1, fft2, ifft, tmp1, tmp2, tmp3, irreversible);
if(t%print_freq==0){
fprintf(stderr,"%d % .8e ",t,t*delta);
@@ -87,6 +88,7 @@ int eea(
double L,
_Complex double* u0,
_Complex double* g,
bool irreversible,
unsigned int print_freq,
unsigned int starting_time,
unsigned int nthreads,
@@ -115,10 +117,13 @@ int eea(
// iterate
for(t=starting_time;t<starting_time+nsteps;t++){
ins_step(u, K1, K2, N1, N2, nu, delta, L, g, fft1, fft2, ifft, tmp1, tmp2, tmp3);
ns_step(u, K1, K2, N1, N2, nu, delta, L, g, fft1, fft2, ifft, tmp1, tmp2, tmp3, irreversible);
// convolution term
ns_T(u,K1,K2,N1,N2,fft1,fft2,ifft);
energy=compute_energy(u, K1, K2);
alpha=compute_alpha(u, K1, K2, g);
alpha=compute_alpha(u, K1, K2, N1, N2, g, L, ifft.fft);
enstrophy=compute_enstrophy(u, K1, K2, L);
// running average
@@ -153,6 +158,7 @@ int quiet(
double L,
_Complex double* u0,
_Complex double* g,
bool irreversible,
unsigned int nthreads,
FILE* savefile
){
@@ -171,7 +177,7 @@ int quiet(
// iterate
for(t=0;t<nsteps;t++){
ins_step(u, K1, K2, N1, N2, nu, delta, L, g, fft1, fft2, ifft, tmp1, tmp2, tmp3);
ns_step(u, K1, K2, N1, N2, nu, delta, L, g, fft1, fft2, ifft, tmp1, tmp2, tmp3, irreversible);
}
// save final entry to savefile
@@ -267,8 +273,8 @@ int copy_u(
return 0;
}
// next time step for Irreversible Navier-Stokes equation
int ins_step(
// next time step
int ns_step(
_Complex double* u,
int K1,
int K2,
@@ -283,12 +289,13 @@ int ins_step(
fft_vect ifft,
_Complex double* tmp1,
_Complex double* tmp2,
_Complex double* tmp3
_Complex double* tmp3,
bool irreversible
){
int kx,ky;
// k1
ins_rhs(tmp1, u, K1, K2, N1, N2, nu, L, g, fft1, fft2, ifft);
ns_rhs(tmp1, u, K1, K2, N1, N2, nu, L, g, fft1, fft2, ifft, irreversible);
// add to output
for(kx=-K1;kx<=K1;kx++){
for(ky=-K2;ky<=K2;ky++){
@@ -303,7 +310,7 @@ int ins_step(
}
}
// k2
ins_rhs(tmp1, tmp2, K1, K2, N1, N2, nu, L, g, fft1, fft2, ifft);
ns_rhs(tmp1, tmp2, K1, K2, N1, N2, nu, L, g, fft1, fft2, ifft, irreversible);
// add to output
for(kx=-K1;kx<=K1;kx++){
for(ky=-K2;ky<=K2;ky++){
@@ -318,7 +325,7 @@ int ins_step(
}
}
// k3
ins_rhs(tmp1, tmp2, K1, K2, N1, N2, nu, L, g, fft1, fft2, ifft);
ns_rhs(tmp1, tmp2, K1, K2, N1, N2, nu, L, g, fft1, fft2, ifft, irreversible);
// add to output
for(kx=-K1;kx<=K1;kx++){
for(ky=-K2;ky<=K2;ky++){
@@ -333,7 +340,7 @@ int ins_step(
}
}
// k4
ins_rhs(tmp1, tmp2, K1, K2, N1, N2, nu, L, g, fft1, fft2, ifft);
ns_rhs(tmp1, tmp2, K1, K2, N1, N2, nu, L, g, fft1, fft2, ifft, irreversible);
// add to output
for(kx=-K1;kx<=K1;kx++){
for(ky=-K2;ky<=K2;ky++){
@@ -344,8 +351,8 @@ int ins_step(
return(0);
}
// right side of Irreversible Navier-Stokes equation
int ins_rhs(
// right side of Irreversible/Reversible Navier-Stokes equation
int ns_rhs(
_Complex double* out,
_Complex double* u,
int K1,
@@ -357,14 +364,21 @@ int ins_rhs(
_Complex double* g,
fft_vect fft1,
fft_vect fft2,
fft_vect ifft
fft_vect ifft,
bool irreversible
){
int kx,ky;
int i;
double alpha;
// compute convolution term
ns_T(u,K1,K2,N1,N2,fft1,fft2,ifft);
if (irreversible) {
alpha=nu;
} else {
alpha=compute_alpha(u,K1,K2,N1,N2,g,L,ifft.fft);
}
/*
// compare convolution term (store result in fft1.fft)
@@ -376,14 +390,13 @@ int ins_rhs(
printf("% .15e\n",sqrt(cmp));
*/
for(i=0; i<(2*K1+1)*(2*K2+1); i++){
out[i]=0;
}
for(kx=-K1;kx<=K1;kx++){
for(ky=-K2;ky<=K2;ky++){
if(kx!=0 || ky!=0){
out[klookup(kx,ky,2*K1+1,2*K2+1)]=-4*M_PI*M_PI/L/L*nu*(kx*kx+ky*ky)*u[klookup(kx,ky,2*K1+1,2*K2+1)]+g[klookup(kx,ky,2*K1+1,2*K2+1)]+4*M_PI*M_PI/L/L/sqrt(kx*kx+ky*ky)*ifft.fft[klookup(kx,ky,N1,N2)];
out[klookup(kx,ky,2*K1+1,2*K2+1)]=-4*M_PI*M_PI/L/L*alpha*(kx*kx+ky*ky)*u[klookup(kx,ky,2*K1+1,2*K2+1)]+g[klookup(kx,ky,2*K1+1,2*K2+1)]+4*M_PI*M_PI/L/L/sqrt(kx*kx+ky*ky)*ifft.fft[klookup(kx,ky,N1,N2)];
}
}
}
@@ -514,6 +527,36 @@ int ns_T_nofft(
return 0;
}
// compute alpha
double compute_alpha(
_Complex double* u,
int K1,
int K2,
int N1,
int N2,
_Complex double* g,
double L,
_Complex double* T
){
_Complex double num=0;
double denom=0;
int kx,ky;
num=0.;
denom=0.;
for(kx=-K1;kx<=K1;kx++){
for(ky=-K2;ky<=K2;ky++){
num+=(L*L/4/M_PI/M_PI*(kx*kx+ky*ky)*g[klookup(kx,ky,2*K1+1,2*K2+1)]+sqrt(kx*kx+ky*ky)*T[klookup(kx,ky,N1,N2)])*conj(u[klookup(kx,ky,2*K1+1,2*K2+1)]);
denom+=__real__ (kx*kx+ky*ky)*(kx*kx+ky*ky)*u[klookup(kx,ky,2*K1+1,2*K2+1)]*conj(u[klookup(kx,ky,2*K1+1,2*K2+1)]);
}
}
return __real__ num/denom;
}
/*
// compute alpha
double compute_alpha(
_Complex double* u,
@@ -533,7 +576,7 @@ double compute_alpha(
}
return __real__ (num/denom);
}
}*/
// compute energy
double compute_energy(