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Rewrite: change cli arguments handling

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This commit is contained in:
Ian Jauslin 2022-05-18 09:57:06 +02:00
parent c32c52c94a
commit f21ab0d795
5 changed files with 652 additions and 324 deletions
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17
src/driving.c Normal file
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@ -0,0 +1,17 @@
#include "driving.h"
#include <math.h>
_Complex double g_test(
int kx,
int ky
){
//return sqrt(kx*kx*ky*ky)*exp(-(kx*kx+ky*ky));
if(kx==2 && ky==-1){
return 0.5+sqrt(3)/2*I;
}
else if(kx==-2 && ky==1){
return 0.5-sqrt(3)/2*I;
}
return 0.;
}

8
src/driving.h Normal file
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@ -0,0 +1,8 @@
#ifndef DRIVING_H
#define DRIVING_H
#include <complex.h>
_Complex double g_test( int kx, int ky);
#endif

490
src/main.c
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@ -1,43 +1,77 @@
#define VERSION "0.0" #define VERSION "0.1"
#include <math.h> #include <math.h>
#include <complex.h> #include <complex.h>
#include <fftw3.h> #include <fftw3.h>
#include <string.h> #include <string.h>
#include <stdlib.h> #include <stdlib.h>
#include <stdbool.h>
#include "navier-stokes.h" #include "navier-stokes.h"
#include "driving.h"
// usage message // usage message
int print_usage(); int print_usage();
// read command line arguments // read command line arguments
int read_args(int argc, const char* argv[], ns_params* params, unsigned int* nsteps, unsigned int* computation_nr); int read_args(int argc, const char* argv[], char** params, unsigned int* driving_force, unsigned int* command);
int read_params(char* params, int* K1, int* K2, int* N1, int* N2, unsigned int* nsteps, double* nu, double* delta, unsigned int* print_freq);
// compute enstrophy as a function of time in the I-NS equation int set_parameter(char* lhs, char* rhs, int* K1, int* K2, int* N1, int* N2, unsigned int* nsteps, double* nu, double* delta, unsigned int* print_freq, bool* setN1, bool* setN2);
int enstrophy(ns_params params, unsigned int Nsteps);
#define COMPUTATION_ENSTROPHY 1 #define COMMAND_UK 1
int main (int argc, const char* argv[]){ #define COMMAND_ENSTROPHY 2
ns_params params;
#define DRIVING_TEST 1
int main (
int argc,
const char* argv[]
){
char* params=NULL;
int K1,K2;
int N1,N2;
unsigned int nsteps; unsigned int nsteps;
double nu,delta;
_Complex double (*g)(int,int);
int ret; int ret;
unsigned int computation_nr; unsigned int driving,command;
unsigned int print_freq;
// default computation: phase diagram command=0;
computation_nr=COMPUTATION_ENSTROPHY; driving=0;
// read command line arguments // read command line arguments
ret=read_args(argc, argv, &params, &nsteps, &computation_nr); ret=read_args(argc, argv, &params, &driving, &command);
if(ret<0){ if(ret<0){
return(-1); return(-1);
} }
if(ret>0){ // read params
return(0); ret=read_params(params, &K1, &K2, &N1, &N2, &nsteps, &nu, &delta, &print_freq);
if(ret<0){
return(-1);
}
// set driving force
switch(driving){
case DRIVING_TEST:
g=g_test;
break;
default:
g=g_test;
break;
} }
// enstrophy // run command
if(computation_nr==COMPUTATION_ENSTROPHY){ if (command==COMMAND_UK){
enstrophy(params, nsteps); uk(K1, K2, N1, N2, nsteps, nu, delta, g, print_freq);
}
else if(command==COMMAND_ENSTROPHY){
enstrophy(K1, K2, N1, N2, nsteps, nu, delta, g, print_freq);
}
else if(command==0){
fprintf(stderr, "error: no command specified\n");
print_usage();
} }
return(0); return(0);
@ -45,44 +79,25 @@ int main (int argc, const char* argv[]){
// usage message // usage message
int print_usage(){ int print_usage(){
fprintf(stderr, "usage:\n nstrophy enstrophy [-h timestep] [-K modes] [-v] [-N nsteps]\n\n nstrophy -V [-v]\n\n"); fprintf(stderr, "usage:\n nstrophy [-p parameters] [-g driving_force] <command>\n\n");
return(0); return(0);
} }
// read command line arguments // read command line arguments
#define CP_FLAG_TIMESTEP 1 #define CP_FLAG_PARAMS 1
#define CP_FLAG_NSTEPS 2 #define CP_FLAG_DRIVING 2
#define CP_FLAG_MODES 3 int read_args(
#define CP_FLAG_NU 4 int argc,
int read_args(int argc, const char* argv[], ns_params* params, unsigned int* nsteps, unsigned int* computation_nr){ const char* argv[],
char** params,
unsigned int* driving_force,
unsigned int* command
){
int i; int i;
int ret;
// temporary int
int tmp_int;
// temporary unsigned int
unsigned int tmp_uint;
// temporary double
double tmp_double;
// pointers // pointers
char* ptr; char* ptr;
// flag that indicates what argument is being read // flag that indicates what argument is being read
int flag=0; int flag=0;
// print version and exit
char Vflag=0;
// defaults
/*
params->K=16;
params->h=1e-3/(2*params->K+1);
*nsteps=10000000;
params->nu=1./1024/(2*params->K+1);
*/
params->K=16;
//h=2^-13
params->h=0.0001220703125;
//nu=2^-11
*nsteps=10000000;
params->nu=0.00048828125;
// loop over arguments // loop over arguments
for(i=1;i<argc;i++){ for(i=1;i<argc;i++){
@ -91,24 +106,12 @@ int read_args(int argc, const char* argv[], ns_params* params, unsigned int* nst
for(ptr=((char*)argv[i])+1;*ptr!='\0';ptr++){ for(ptr=((char*)argv[i])+1;*ptr!='\0';ptr++){
switch(*ptr){ switch(*ptr){
// timestep // timestep
case 'h': case 'p':
flag=CP_FLAG_TIMESTEP; flag=CP_FLAG_PARAMS;
break; break;
// nsteps // nsteps
case 'N': case 'g':
flag=CP_FLAG_NSTEPS; flag=CP_FLAG_DRIVING;
break;
// modes
case 'K':
flag=CP_FLAG_MODES;
break;
// friction
case 'n':
flag=CP_FLAG_NU;
break;
// print version
case 'V':
Vflag=1;
break; break;
default: default:
fprintf(stderr, "unrecognized option '-%c'\n", *ptr); fprintf(stderr, "unrecognized option '-%c'\n", *ptr);
@ -118,206 +121,241 @@ int read_args(int argc, const char* argv[], ns_params* params, unsigned int* nst
} }
} }
} }
// timestep // params
else if(flag==CP_FLAG_TIMESTEP){ else if(flag==CP_FLAG_PARAMS){
ret=sscanf(argv[i],"%lf",&tmp_double); *params=(char*)argv[i];
if(ret!=1){
fprintf(stderr, "error: '-h' should be followed by a double\n got '%s'\n",argv[i]);
return(-1);
}
params->h=tmp_double;
flag=0; flag=0;
} }
// nsteps // driving force
else if(flag==CP_FLAG_NSTEPS){ else if(flag==CP_FLAG_DRIVING){
ret=sscanf(argv[i],"%u",&tmp_uint); if (strcmp(argv[i],"test")==0){
if(ret!=1){ *driving_force=DRIVING_TEST;
fprintf(stderr, "error: '-N' should be followed by an unsigned int\n got '%s'\n",argv[i]); }
else{
fprintf(stderr, "error: unrecognized driving force '%s'\n",argv[i]);
return(-1); return(-1);
} }
*nsteps=tmp_uint;
flag=0;
}
// modes
else if(flag==CP_FLAG_MODES){
ret=sscanf(argv[i],"%d",&tmp_int);
if(ret!=1){
fprintf(stderr, "error: '-K' should be followed by an int\n got '%s'\n",argv[i]);
return(-1);
}
params->K=tmp_int;
flag=0;
}
// friction
else if(flag==CP_FLAG_TIMESTEP){
ret=sscanf(argv[i],"%lf",&tmp_double);
if(ret!=1){
fprintf(stderr, "error: '-n' should be followed by a double\n got '%s'\n",argv[i]);
return(-1);
}
params->nu=tmp_double;
flag=0; flag=0;
} }
// computation to run // computation to run
else{ else{
if(strcmp(argv[i], "enstrophy")==0){ if(strcmp(argv[i], "uk")==0){
*computation_nr=COMPUTATION_ENSTROPHY; *command=COMMAND_UK;
}
else if(strcmp(argv[i], "enstrophy")==0){
*command=COMMAND_ENSTROPHY;
} }
else{ else{
fprintf(stderr, "error: unrecognized computation: '%s'\n",argv[i]); fprintf(stderr, "error: unrecognized command: '%s'\n",argv[i]);
print_usage();
return(-1); return(-1);
} }
flag=0; flag=0;
} }
} }
// print version and exit return(0);
if(Vflag==1){ }
printf("nstrophy " VERSION "\n");
return(1); // read parameters string
int read_params(
char* params,
int* K1,
int* K2,
int* N1,
int* N2,
unsigned int* nsteps,
double* nu,
double* delta,
unsigned int* print_freq
){
int ret;
// pointer in params
char* ptr;
// buffer and associated pointer
char *buffer_lhs, *lhs_ptr;
char *buffer_rhs, *rhs_ptr;
// whether N was set explicitly
bool setN1=false;
bool setN2=false;
// whether lhs (false is rhs)
bool lhs=true;
// defaults
*K1=16;
*K2=*K1;
//delta=2^-13
*delta=0.0001220703125;
//nu=2^-11
*nu=0.00048828125;
*nsteps=10000000;
*print_freq=1000;
if (params!=NULL){
// init
buffer_lhs=calloc(sizeof(char),strlen(params));
lhs_ptr=buffer_lhs;
*lhs_ptr='\0';
buffer_rhs=calloc(sizeof(char),strlen(params));
rhs_ptr=buffer_rhs;
*rhs_ptr='\0';
for(ptr=params;*ptr!='\0';ptr++){
switch(*ptr){
case '=':
// reset buffer
rhs_ptr=buffer_rhs;
*rhs_ptr='\0';
lhs=false;
break;
case ';':
//set parameter
ret=set_parameter(buffer_lhs,buffer_rhs,K1,K2,N1,N2,nsteps,nu,delta,print_freq,&setN1,&setN2);
if(ret<0){
return ret;
}
// reset buffer
lhs_ptr=buffer_lhs;
*lhs_ptr='\0';
lhs=true;
break;
default:
// add to buffer
if (lhs){
*lhs_ptr=*ptr;
lhs_ptr++;
*lhs_ptr='\0';
}
else{
*rhs_ptr=*ptr;
rhs_ptr++;
*rhs_ptr='\0';
}
break;
}
}
// set last param
if (*params!='\0'){
ret=set_parameter(buffer_lhs,buffer_rhs,K1,K2,N1,N2,nsteps,nu,delta,print_freq,&setN1,&setN2);
if(ret<0){
return ret;
}
}
// free vects
free(buffer_lhs);
free(buffer_rhs);
}
// if N not set explicitly, set it
if (!setN1){
*N1=4*(*K1)+1;
}
if (!setN2){
*N2=4*(*K2)+1;
} }
return(0); return(0);
} }
// compute enstrophy as a function of time in the I-NS equation
int enstrophy(ns_params params, unsigned int Nsteps){
_Complex double* u;
_Complex double* tmp1;
_Complex double* tmp2;
_Complex double* tmp3;
_Complex double alpha;
_Complex double avg;
unsigned int t;
int kx,ky;
fft_vects fft_vects;
double rescale;
// sizes // set a parameter from the parameter string
params.S=2*params.K+1; int set_parameter(
params.N=4*params.K+1; char* lhs,
char* rhs,
int* K1,
int* K2,
int* N1,
int* N2,
unsigned int* nsteps,
double* nu,
double* delta,
unsigned int* print_freq,
bool* setN1,
bool* setN2
){
int ret;
// velocity field if (strcmp(lhs,"K1")==0){
u=calloc(sizeof(_Complex double),params.S*params.S); ret=sscanf(rhs,"%d",K1);
params.g=calloc(sizeof(_Complex double),params.S*params.S); if(ret!=1){
// allocate tmp vectors for computation fprintf(stderr, "error: parameter 'K1' should be an integer\n got '%s'\n",rhs);
tmp1=calloc(sizeof(_Complex double),params.S*params.S); return(-1);
tmp2=calloc(sizeof(_Complex double),params.S*params.S);
tmp3=calloc(sizeof(_Complex double),params.S*params.S);
/*
srand(17);
// initial value
for(ky=0;ky<=params.K;ky++){
u[KLOOKUP(0,ky,params.S)]=(-RAND_MAX*0.5+rand())*1.0/RAND_MAX+(-RAND_MAX*0.5+rand())*1.0/RAND_MAX*I;
}
for(kx=1;kx<=params.K;kx++){
for(ky=-params.K;ky<=params.K;ky++){
u[KLOOKUP(kx,ky,params.S)]=(-RAND_MAX*0.5+rand())*1.0/RAND_MAX+(-RAND_MAX*0.5+rand())*1.0/RAND_MAX*I;
} }
} }
for(ky=-params.K;ky<=-1;ky++){ else if (strcmp(lhs,"K2")==0){
u[KLOOKUP(0,ky,params.S)]=conj(u[KLOOKUP(0,-ky,params.S)]); ret=sscanf(rhs,"%d",K2);
} if(ret!=1){
for(kx=-params.K;kx<=-1;kx++){ fprintf(stderr, "error: parameter 'K2' should be an integer\n got '%s'\n",rhs);
for(ky=-params.K;ky<=params.K;ky++){ return(-1);
u[KLOOKUP(kx,ky,params.S)]=conj(u[KLOOKUP(-kx,-ky,params.S)]);
} }
} }
rescale=0; else if (strcmp(lhs,"K")==0){
for(kx=-params.K;kx<=params.K;kx++){ ret=sscanf(rhs,"%d",K1);
for(ky=-params.K;ky<=params.K;ky++){ if(ret!=1){
rescale=rescale+((__real__ u[KLOOKUP(kx,ky,params.S)])*(__real__ u[KLOOKUP(kx,ky,params.S)])+(__imag__ u[KLOOKUP(kx,ky,params.S)])*(__imag__ u[KLOOKUP(kx,ky,params.S)]))*(kx*kx+ky*ky); fprintf(stderr, "error: parameter 'K' should be an integer\n got '%s'\n",rhs);
return(-1);
}
*K2=*K1;
}
else if (strcmp(lhs,"N1")==0){
ret=sscanf(rhs,"%d",N1);
if(ret!=1){
fprintf(stderr, "error: parameter 'N1' should be an integer\n got '%s'\n",rhs);
return(-1);
}
*setN1=true;
}
else if (strcmp(lhs,"N2")==0){
ret=sscanf(rhs,"%d",N2);
if(ret!=1){
fprintf(stderr, "error: parameter 'N2' should be an integer\n got '%s'\n",rhs);
return(-1);
}
*setN2=true;
}
else if (strcmp(lhs,"N")==0){
ret=sscanf(rhs,"%d",N1);
if(ret!=1){
fprintf(stderr, "error: parameter 'N' should be an integer\n got '%s'\n",rhs);
return(-1);
}
*N2=*N1;
*setN1=true;
*setN2=true;
}
else if (strcmp(lhs,"nsteps")==0){
ret=sscanf(rhs,"%u",nsteps);
if(ret!=1){
fprintf(stderr, "error: parameter 'nsteps' should be an unsigned integer\n got '%s'\n",rhs);
return(-1);
} }
} }
for(kx=-params.K;kx<=params.K;kx++){ else if (strcmp(lhs,"nu")==0){
for(ky=-params.K;ky<=params.K;ky++){ ret=sscanf(rhs,"%lf",nu);
u[KLOOKUP(kx,ky,params.S)]=u[KLOOKUP(kx,ky,params.S)]*sqrt(155.1/rescale); if(ret!=1){
fprintf(stderr, "error: parameter 'nu' should be a double\n got '%s'\n",rhs);
return(-1);
} }
} }
*/ else if (strcmp(lhs,"delta")==0){
/* ret=sscanf(rhs,"%lf",delta);
for(kx=-params.K;kx<=params.K;kx++){ if(ret!=1){
for(ky=-params.K;ky<=params.K;ky++){ fprintf(stderr, "error: parameter 'delta' should be a double\n got '%s'\n",rhs);
u[KLOOKUP(kx,ky,params.S)]=1.; return(-1);
} }
} }
*/ else if (strcmp(lhs,"print_freq")==0){
for(kx=-params.K;kx<=params.K;kx++){ ret=sscanf(rhs,"%u",print_freq);
for(ky=-params.K;ky<=params.K;ky++){ if(ret!=1){
u[KLOOKUP(kx,ky,params.S)]=exp(-sqrt(kx*kx+ky*ky)); fprintf(stderr, "error: parameter 'print_freq' should be an unsigned integer\n got '%s'\n",rhs);
return(-1);
} }
} }
else{
fprintf(stderr, "error: unrecognized parameter '%s'\n",lhs);
// driving force return(-1);
for(kx=-params.K;kx<=params.K;kx++){
for(ky=-params.K;ky<=params.K;ky++){
//params.g[KLOOKUP(kx,ky,params.S)]=sqrt(kx*kx*ky*ky)*exp(-(kx*kx+ky*ky));
if(kx==2 && ky==-1){
params.g[KLOOKUP(kx,ky,params.S)]=0.5+sqrt(3)/2*I;
}
else if(kx==-2 && ky==1){
params.g[KLOOKUP(kx,ky,params.S)]=0.5-sqrt(3)/2*I;
}
else{
params.g[KLOOKUP(kx,ky,params.S)]=0;
}
}
} }
// prepare vectors for fft
fft_vects.fft1=fftw_malloc(sizeof(fftw_complex)*params.N*params.N);
fft_vects.fft1_plan=fftw_plan_dft_2d((int)params.N,(int)params.N, fft_vects.fft1, fft_vects.fft1, FFTW_FORWARD, FFTW_MEASURE);
fft_vects.fft2=fftw_malloc(sizeof(fftw_complex)*params.N*params.N);
fft_vects.fft2_plan=fftw_plan_dft_2d((int)params.N,(int)params.N, fft_vects.fft2, fft_vects.fft2, FFTW_FORWARD, FFTW_MEASURE);
fft_vects.invfft=fftw_malloc(sizeof(fftw_complex)*params.N*params.N);
fft_vects.invfft_plan=fftw_plan_dft_2d((int)params.N,(int)params.N, fft_vects.invfft, fft_vects.invfft, FFTW_BACKWARD, FFTW_MEASURE);
// init running average
avg=0;
// iterate
for(t=0;t<Nsteps;t++){
ins_step(u, params, fft_vects, tmp1, tmp2, tmp3);
alpha=compute_alpha(u, params);
/*
// to avoid errors building up in imaginary part
for(kx=-params.K;kx<=params.K;kx++){
for(ky=-params.K;ky<=params.K;ky++){
u[KLOOKUP(kx,ky,params.S)]=__real__ u[KLOOKUP(kx,ky,params.S)];
}
}
*/
// running average
if(t>0){
avg=avg-(avg-alpha)/t;
}
if(t>0 && t%1000==0){
fprintf(stderr,"% .15e % .15e % .15e % .15e % .15e\n",t*params.h, __real__ avg, __imag__ avg, __real__ alpha, __imag__ alpha);
printf("% .15e % .15e % .15e % .15e % .15e\n",t*params.h, __real__ avg, __imag__ avg, __real__ alpha, __imag__ alpha);
}
}
// free memory
fftw_destroy_plan(fft_vects.fft1_plan);
fftw_destroy_plan(fft_vects.fft2_plan);
fftw_destroy_plan(fft_vects.invfft_plan);
fftw_free(fft_vects.fft1);
fftw_free(fft_vects.fft2);
fftw_free(fft_vects.invfft);
free(tmp3);
free(tmp2);
free(tmp1);
free(params.g);
free(u);
return(0); return(0);
} }

408
src/navier-stokes.c
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@ -1,63 +1,311 @@
#include "navier-stokes.h" #include "navier-stokes.h"
#include <math.h> #include <math.h>
#include <stdlib.h>
#define M_PI 3.14159265358979323846 #define M_PI 3.14159265358979323846
// compute solution as a function of time
int uk(
int K1,
int K2,
int N1,
int N2,
unsigned int nsteps,
double nu,
double delta,
_Complex double (*g)(int,int),
unsigned int print_freq
){
_Complex double* u;
_Complex double* tmp1;
_Complex double* tmp2;
_Complex double* tmp3;
unsigned int t;
fft_vect fft1;
fft_vect fft2;
fft_vect ifft;
int kx,ky;
ns_init_tmps(&u, &tmp1, &tmp2, &tmp3, &fft1, &fft2, &ifft, K1, K2, N1, N2);
ns_init_u(u, K1, K2);
// iterate
for(t=0;t<nsteps;t++){
ins_step(u, K1, K2, N1, N2, nu, delta, g, fft1, fft2, ifft, tmp1, tmp2, tmp3);
if(t%print_freq==0){
fprintf(stderr,"% .8e ",t*delta);
printf("% .15e ",t*delta);
for(kx=-K1;kx<=K1;kx++){
for (ky=-K2;ky<=K2;ky++){
if (kx*kx+ky*ky<=1){
fprintf(stderr,"% .8e % .8e ",__real__ u[klookup(kx,ky,2*K1+1,2*K2+1)], __imag__ u[klookup(kx,ky,2*K1+1,2*K2+1)]);
}
printf("% .8e % .8e ",__real__ u[klookup(kx,ky,2*K1+1,2*K2+1)], __imag__ u[klookup(kx,ky,2*K1+1,2*K2+1)]);
}
}
fprintf(stderr,"\n");
printf("\n");
}
}
ns_free_tmps(u, tmp1, tmp2, tmp3, fft1, fft2, ifft);
return(0);
}
// compute enstrophy as a function of time in the I-NS equation
int enstrophy(
int K1,
int K2,
int N1,
int N2,
unsigned int nsteps,
double nu,
double delta,
_Complex double (*g)(int,int),
unsigned int print_freq
){
_Complex double* u;
_Complex double* tmp1;
_Complex double* tmp2;
_Complex double* tmp3;
_Complex double alpha;
_Complex double avg;
unsigned int t;
fft_vect fft1;
fft_vect fft2;
fft_vect ifft;
ns_init_tmps(&u, &tmp1, &tmp2, &tmp3, &fft1, &fft2, &ifft, K1, K2, N1, N2);
ns_init_u(u, K1, K2);
// init running average
avg=0;
// iterate
for(t=0;t<nsteps;t++){
ins_step(u, K1, K2, N1, N2, nu, delta, g, fft1, fft2, ifft, tmp1, tmp2, tmp3);
alpha=compute_alpha(u, K1, K2, g);
// running average
if(t>0){
avg=avg-(avg-alpha)/t;
}
if(t>0 && t%print_freq==0){
fprintf(stderr,"% .15e % .15e % .15e % .15e % .15e\n",t*delta, __real__ avg, __imag__ avg, __real__ alpha, __imag__ alpha);
printf("% .15e % .15e % .15e % .15e % .15e\n",t*delta, __real__ avg, __imag__ avg, __real__ alpha, __imag__ alpha);
}
}
ns_free_tmps(u, tmp1, tmp2, tmp3, fft1, fft2, ifft);
return(0);
}
// initialize vectors for computation
int ns_init_tmps(
_Complex double ** u,
_Complex double ** tmp1,
_Complex double ** tmp2,
_Complex double ** tmp3,
fft_vect* fft1,
fft_vect* fft2,
fft_vect* ifft,
int K1,
int K2,
int N1,
int N2
){
// velocity field
*u=calloc(sizeof(_Complex double),(2*K1+1)*(2*K2+1));
// allocate tmp vectors for computation
*tmp1=calloc(sizeof(_Complex double),(2*K1+1)*(2*K2+1));
*tmp2=calloc(sizeof(_Complex double),(2*K1+1)*(2*K2+1));
*tmp3=calloc(sizeof(_Complex double),(2*K1+1)*(2*K2+1));
// prepare vectors for fft
fft1->fft=fftw_malloc(sizeof(fftw_complex)*N1*N2);
fft1->fft_plan=fftw_plan_dft_2d(N1,N2, fft1->fft, fft1->fft, FFTW_FORWARD, FFTW_MEASURE);
fft2->fft=fftw_malloc(sizeof(fftw_complex)*N1*N2);
fft2->fft_plan=fftw_plan_dft_2d(N1,N2, fft2->fft, fft2->fft, FFTW_FORWARD, FFTW_MEASURE);
ifft->fft=fftw_malloc(sizeof(fftw_complex)*N1*N2);
ifft->fft_plan=fftw_plan_dft_2d(N1,N2, ifft->fft, ifft->fft, FFTW_BACKWARD, FFTW_MEASURE);
return 0;
}
// release vectors
int ns_free_tmps(
_Complex double* u,
_Complex double* tmp1,
_Complex double* tmp2,
_Complex double* tmp3,
fft_vect fft1,
fft_vect fft2,
fft_vect ifft
){
// free memory
fftw_destroy_plan(fft1.fft_plan);
fftw_destroy_plan(fft2.fft_plan);
fftw_destroy_plan(ifft.fft_plan);
fftw_free(fft1.fft);
fftw_free(fft2.fft);
fftw_free(ifft.fft);
fftw_cleanup();
free(tmp3);
free(tmp2);
free(tmp1);
free(u);
return 0;
}
// initial value
int ns_init_u(
_Complex double* u,
int K1,
int K2
){
int kx,ky;
/*
double rescale;
srand(17);
// random init (set half, then the other half are the conjugates)
for(ky=0;ky<=K2;ky++){
u[klookup(0,ky,2*K1+1,2*K2+1)]=(-RAND_MAX*0.5+rand())*1.0/RAND_MAX+(-RAND_MAX*0.5+rand())*1.0/RAND_MAX*I;
}
for(kx=1;kx<=K1;kx++){
for(ky=-K2;ky<=K2;ky++){
u[klookup(kx,ky,2*K1+1,2*K2+1)]=(-RAND_MAX*0.5+rand())*1.0/RAND_MAX+(-RAND_MAX*0.5+rand())*1.0/RAND_MAX*I;
}
}
// conjugates
for(ky=-K2;ky<=-1;ky++){
u[klookup(0,ky,2*K1+1,2*K2+1)]=conj(u[klookup(0,-ky,2*K1+1,2*K2+1)]);
}
for(kx=-K1;kx<=-1;kx++){
for(ky=-K2;ky<=K2;ky++){
u[klookup(kx,ky,2*K1+1,2*K2+1)]=conj(u[klookup(-kx,-ky,2*K1+1,2*K2+1)]);
}
}
// rescale: 1/k decay
rescale=0;
for(kx=-K1;kx<=K1;kx++){
for(ky=-K2;ky<=K2;ky++){
rescale=rescale+((__real__ u[klookup(kx,ky,2*K1+1,2*K2+1)])*(__real__ u[klookup(kx,ky,2*K1+1,2*K2+1)])+(__imag__ u[klookup(kx,ky,2*K1+1,2*K2+1)])*(__imag__ u[klookup(kx,ky,2*K1+1,2*K2+1)]))*(kx*kx+ky*ky);
}
}
for(kx=-K1;kx<=K1;kx++){
for(ky=-K2;ky<=K2;ky++){
u[klookup(kx,ky,2*K1+1,2*K2+1)]=u[klookup(kx,ky,2*K1+1,2*K2+1)]*sqrt(155.1/rescale);
}
}
*/
/*
// constant init
for(kx=-K1;kx<=K1;kx++){
for(ky=-K2;ky<=K2;ky++){
u[klookup(kx,ky,2*K1+1,2*K2+1)]=1.;
}
}
*/
// exponentially decaying init
for(kx=-K1;kx<=K1;kx++){
for(ky=-K2;ky<=K2;ky++){
u[klookup(kx,ky,2*K1+1,2*K2+1)]=exp(-sqrt(kx*kx+ky*ky));
}
}
return 0;
}
// next time step for Irreversible Navier-Stokes equation // next time step for Irreversible Navier-Stokes equation
int ins_step(_Complex double* u, ns_params params, fft_vects vects, _Complex double* tmp1, _Complex double* tmp2, _Complex double* tmp3){ int ins_step(
_Complex double* u,
int K1,
int K2,
int N1,
int N2,
double nu,
double delta,
_Complex double (*g)(int,int),
fft_vect fft1,
fft_vect fft2,
fft_vect ifft,
_Complex double* tmp1,
_Complex double* tmp2,
_Complex double* tmp3
){
int kx,ky; int kx,ky;
// k1 // k1
ins_rhs(tmp1, u, params, vects); ins_rhs(tmp1, u, K1, K2, N1, N2, nu, g, fft1, fft2, ifft);
// add to output // add to output
for(kx=-params.K;kx<=params.K;kx++){ for(kx=-K1;kx<=K1;kx++){
for(ky=-params.K;ky<=params.K;ky++){ for(ky=-K2;ky<=K2;ky++){
tmp3[KLOOKUP(kx,ky,params.S)]=u[KLOOKUP(kx,ky,params.S)]+params.h/6*tmp1[KLOOKUP(kx,ky,params.S)]; tmp3[klookup(kx,ky,2*K1+1,2*K2+1)]=u[klookup(kx,ky,2*K1+1,2*K2+1)]+delta/6*tmp1[klookup(kx,ky,2*K1+1,2*K2+1)];
} }
} }
// u+h*k1/2 // u+h*k1/2
for(kx=-params.K;kx<=params.K;kx++){ for(kx=-K1;kx<=K1;kx++){
for(ky=-params.K;ky<=params.K;ky++){ for(ky=-K2;ky<=K2;ky++){
tmp2[KLOOKUP(kx,ky,params.S)]=u[KLOOKUP(kx,ky,params.S)]+params.h/2*tmp1[KLOOKUP(kx,ky,params.S)]; tmp2[klookup(kx,ky,2*K1+1,2*K2+1)]=u[klookup(kx,ky,2*K1+1,2*K2+1)]+delta/2*tmp1[klookup(kx,ky,2*K1+1,2*K2+1)];
} }
} }
// k2 // k2
ins_rhs(tmp1, tmp2, params, vects); ins_rhs(tmp1, tmp2, K1, K2, N1, N2, nu, g, fft1, fft2, ifft);
// add to output // add to output
for(kx=-params.K;kx<=params.K;kx++){ for(kx=-K1;kx<=K1;kx++){
for(ky=-params.K;ky<=params.K;ky++){ for(ky=-K2;ky<=K2;ky++){
tmp3[KLOOKUP(kx,ky,params.S)]+=params.h/3*tmp1[KLOOKUP(kx,ky,params.S)]; tmp3[klookup(kx,ky,2*K1+1,2*K2+1)]+=delta/3*tmp1[klookup(kx,ky,2*K1+1,2*K2+1)];
} }
} }
// u+h*k2/2 // u+h*k2/2
for(kx=-params.K;kx<=params.K;kx++){ for(kx=-K1;kx<=K1;kx++){
for(ky=-params.K;ky<=params.K;ky++){ for(ky=-K2;ky<=K2;ky++){
tmp2[KLOOKUP(kx,ky,params.S)]=u[KLOOKUP(kx,ky,params.S)]+params.h/2*tmp1[KLOOKUP(kx,ky,params.S)]; tmp2[klookup(kx,ky,2*K1+1,2*K2+1)]=u[klookup(kx,ky,2*K1+1,2*K2+1)]+delta/2*tmp1[klookup(kx,ky,2*K1+1,2*K2+1)];
} }
} }
// k3 // k3
ins_rhs(tmp1, tmp2, params, vects); ins_rhs(tmp1, tmp2, K1, K2, N1, N2, nu, g, fft1, fft2, ifft);
// add to output // add to output
for(kx=-params.K;kx<=params.K;kx++){ for(kx=-K1;kx<=K1;kx++){
for(ky=-params.K;ky<=params.K;ky++){ for(ky=-K2;ky<=K2;ky++){
tmp3[KLOOKUP(kx,ky,params.S)]+=params.h/3*tmp1[KLOOKUP(kx,ky,params.S)]; tmp3[klookup(kx,ky,2*K1+1,2*K2+1)]+=delta/3*tmp1[klookup(kx,ky,2*K1+1,2*K2+1)];
} }
} }
// u+h*k3 // u+h*k3
for(kx=-params.K;kx<=params.K;kx++){ for(kx=-K1;kx<=K1;kx++){
for(ky=-params.K;ky<=params.K;ky++){ for(ky=-K2;ky<=K2;ky++){
tmp2[KLOOKUP(kx,ky,params.S)]=u[KLOOKUP(kx,ky,params.S)]+params.h*tmp1[KLOOKUP(kx,ky,params.S)]; tmp2[klookup(kx,ky,2*K1+1,2*K2+1)]=u[klookup(kx,ky,2*K1+1,2*K2+1)]+delta*tmp1[klookup(kx,ky,2*K1+1,2*K2+1)];
} }
} }
// k4 // k4
ins_rhs(tmp1, tmp2, params, vects); ins_rhs(tmp1, tmp2, K1, K2, N1, N2, nu, g, fft1, fft2, ifft);
// add to output // add to output
for(kx=-params.K;kx<=params.K;kx++){ for(kx=-K1;kx<=K1;kx++){
for(ky=-params.K;ky<=params.K;ky++){ for(ky=-K2;ky<=K2;ky++){
u[KLOOKUP(kx,ky,params.S)]=tmp3[KLOOKUP(kx,ky,params.S)]+params.h/6*tmp1[KLOOKUP(kx,ky,params.S)]; u[klookup(kx,ky,2*K1+1,2*K2+1)]=tmp3[klookup(kx,ky,2*K1+1,2*K2+1)]+delta/6*tmp1[klookup(kx,ky,2*K1+1,2*K2+1)];
} }
} }
@ -65,74 +313,82 @@ int ins_step(_Complex double* u, ns_params params, fft_vects vects, _Complex dou
} }
// right side of Irreversible Navier-Stokes equation // right side of Irreversible Navier-Stokes equation
int ins_rhs(_Complex double* out, _Complex double* u, ns_params params, fft_vects vects){ int ins_rhs(
_Complex double* out,
_Complex double* u,
int K1,
int K2,
int N1,
int N2,
double nu,
_Complex double (*g)(int,int),
fft_vect fft1,
fft_vect fft2,
fft_vect ifft
){
int kx,ky; int kx,ky;
int i;
// F(px/|p|*u)*F(qy*|q|*u) // F(px/|p|*u)*F(qy*|q|*u)
// init to 0 // init to 0
for(kx=0; kx<params.N*params.N; kx++){ for(i=0; i<N1*N2; i++){
vects.fft1[kx]=0; fft1.fft[i]=0;
vects.fft2[kx]=0; fft2.fft[i]=0;
vects.invfft[kx]=0; ifft.fft[i]=0;
} }
// fill modes // fill modes
for(kx=-params.K;kx<=params.K;kx++){ for(kx=-K1;kx<=K1;kx++){
for(ky=-params.K;ky<=params.K;ky++){ for(ky=-K2;ky<=K2;ky++){
if(kx!=0 || ky!=0){ if(kx!=0 || ky!=0){
vects.fft1[KLOOKUP(kx,ky,params.N)]=kx/sqrt(kx*kx+ky*ky)*u[KLOOKUP(kx,ky,params.S)]; fft1.fft[klookup(kx,ky,N1,N2)]=kx/sqrt(kx*kx+ky*ky)*u[klookup(kx,ky,2*K1+1,2*K2+1)];
vects.fft2[KLOOKUP(kx,ky,params.N)]=ky*sqrt(kx*kx+ky*ky)*u[KLOOKUP(kx,ky,params.S)]; fft2.fft[klookup(kx,ky,N1,N2)]=ky*sqrt(kx*kx+ky*ky)*u[klookup(kx,ky,2*K1+1,2*K2+1)];
} }
} }
} }
// fft // fft
fftw_execute(vects.fft1_plan); fftw_execute(fft1.fft_plan);
fftw_execute(fft2.fft_plan);
fftw_execute(vects.fft2_plan); // write to ifft
// write to invfft for(i=0;i<N1*N2;i++){
for(kx=-2*params.K;kx<=2*params.K;kx++){ ifft.fft[i]=fft1.fft[i]*fft2.fft[i];
for(ky=-2*params.K;ky<=2*params.K;ky++){
vects.invfft[KLOOKUP(kx,ky,params.N)]=vects.fft1[KLOOKUP(kx,ky,params.N)]*vects.fft2[KLOOKUP(kx,ky,params.N)];
}
} }
// F(py/|p|*u)*F(qx*|q|*u) // F(py/|p|*u)*F(qx*|q|*u)
// init to 0 // init to 0
for(kx=0; kx<params.N*params.N; kx++){ for(i=0; i<N1*N2; i++){
vects.fft1[kx]=0; fft1.fft[i]=0;
vects.fft2[kx]=0; fft2.fft[i]=0;
} }
// fill modes // fill modes
for(kx=-params.K;kx<=params.K;kx++){ for(kx=-K1;kx<=K1;kx++){
for(ky=-params.K;ky<=params.K;ky++){ for(ky=-K2;ky<=K2;ky++){
if(kx!=0 || ky!=0){ if(kx!=0 || ky!=0){
vects.fft1[KLOOKUP(kx,ky,params.N)]=ky/sqrt(kx*kx+ky*ky)*u[KLOOKUP(kx,ky,params.S)]; fft1.fft[klookup(kx,ky,N1,N2)]=ky/sqrt(kx*kx+ky*ky)*u[klookup(kx,ky,2*K1+1,2*K2+1)];
vects.fft2[KLOOKUP(kx,ky,params.N)]=kx*sqrt(kx*kx+ky*ky)*u[KLOOKUP(kx,ky,params.S)]; fft2.fft[klookup(kx,ky,N1,N2)]=kx*sqrt(kx*kx+ky*ky)*u[klookup(kx,ky,2*K1+1,2*K2+1)];
} }
} }
} }
// fft // fft
fftw_execute(vects.fft1_plan); fftw_execute(fft1.fft_plan);
fftw_execute(vects.fft2_plan); fftw_execute(fft2.fft_plan);
// write to invfft // write to ifft
for(kx=-2*params.K;kx<=2*params.K;kx++){ for(i=0;i<N1*N2;i++){
for(ky=-2*params.K;ky<=2*params.K;ky++){ ifft.fft[i]=ifft.fft[i]-fft1.fft[i]*fft2.fft[i];
vects.invfft[KLOOKUP(kx,ky,params.N)]=vects.invfft[KLOOKUP(kx,ky,params.N)]-vects.fft1[KLOOKUP(kx,ky,params.N)]*vects.fft2[KLOOKUP(kx,ky,params.N)];
}
} }
// inverse fft // inverse fft
fftw_execute(vects.invfft_plan); fftw_execute(ifft.fft_plan);
// write out // write out
for(kx=0; kx<params.S*params.S; kx++){ for(i=0; i<(2*K1+1)*(2*K2+1); i++){
out[kx]=0; out[i]=0;
} }
for(kx=-params.K;kx<=params.K;kx++){ for(kx=-K1;kx<=K1;kx++){
for(ky=-params.K;ky<=params.K;ky++){ for(ky=-K2;ky<=K2;ky++){
if(kx!=0 || ky!=0){ if(kx!=0 || ky!=0){
out[KLOOKUP(kx,ky,params.S)]=-4*M_PI*M_PI*params.nu*(kx*kx+ky*ky)*u[KLOOKUP(kx,ky,params.S)]+params.g[KLOOKUP(kx,ky,params.S)]+4*M_PI*M_PI/sqrt(kx*kx+ky*ky)*vects.invfft[KLOOKUP(kx,ky,params.N)]/params.N/params.N; out[klookup(kx,ky,2*K1+1,2*K2+1)]=-4*M_PI*M_PI*nu*(kx*kx+ky*ky)*u[klookup(kx,ky,2*K1+1,2*K2+1)]+(*g)(kx,ky)+4*M_PI*M_PI/sqrt(kx*kx+ky*ky)*ifft.fft[klookup(kx,ky,N1,N2)]/N1/N2;
} }
} }
} }
@ -142,17 +398,33 @@ int ins_rhs(_Complex double* out, _Complex double* u, ns_params params, fft_vect
// compute alpha // compute alpha
_Complex double compute_alpha(_Complex double* u, ns_params params){ _Complex double compute_alpha(
_Complex double* u,
int K1,
int K2,
_Complex double (*g)(int,int)
){
_Complex double num=0; _Complex double num=0;
_Complex double denom=0; _Complex double denom=0;
int kx,ky; int kx,ky;
for(kx=-params.K;kx<=params.K;kx++){ for(kx=-K1;kx<=K1;kx++){
for(ky=-params.K;ky<=params.K;ky++){ for(ky=-K2;ky<=K2;ky++){
denom+=(kx*kx+ky*ky)*(kx*kx+ky*ky)*u[KLOOKUP(kx,ky,params.S)]*conj(u[KLOOKUP(kx,ky,params.S)])*(1+(ky!=0?kx*kx/ky/ky:0)); denom+=(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)])*(1+(ky!=0?kx*kx/ky/ky:0));
num+=(kx*kx+ky*ky)*u[KLOOKUP(kx,ky,params.S)]*conj(params.g[KLOOKUP(kx,ky,params.S)])*(1+(ky!=0?kx*kx/ky/ky:0)); num+=(kx*kx+ky*ky)*u[klookup(kx,ky,2*K1+1,2*K2+1)]*conj((*g)(kx,ky))*(1+(ky!=0?kx*kx/ky/ky:0));
} }
} }
return(num/denom); return(num/denom);
} }
// get index for kx,ky in array of size S
int klookup(
int kx,
int ky,
int S1,
int S2
){
return (kx>=0 ? kx : S1+kx)*S2 + (ky>=0 ? ky : S2+ky);
}

53
src/navier-stokes.h
View File

@ -4,45 +4,38 @@
#include <complex.h> #include <complex.h>
#include <fftw3.h> #include <fftw3.h>
// to extract elements from array of size S representing a function of momentum, use
// array[KEXTRACT(kx,ky,size)]
#define KLOOKUP(X,Y,S) (X>=0?X:S+X)*S+(Y>=0?Y:S+Y)
// parameters for the NS equation
typedef struct ns_params {
// number of modes
int K;
// 2*K+1
int S;
// 4*K+1
int N;
// forcing term
_Complex double* g;
// time step
double h;
// friction
double nu;
} ns_params;
// arrays on which the ffts are performed // arrays on which the ffts are performed
typedef struct fft_vects { typedef struct fft_vects {
fftw_complex* fft1; fftw_complex* fft;
fftw_complex* fft2; fftw_plan fft_plan;
fftw_complex* invfft; } fft_vect;
fftw_plan fft1_plan;
fftw_plan fft2_plan; // compute u_k
fftw_plan invfft_plan; int uk( int K1, int K2, int N1, int N2, unsigned int nsteps, double nu, double delta, _Complex double (*g)(int,int), unsigned int print_freq);
} fft_vects;
// compute enstrophy
int enstrophy( int K1, int K2, int N1, int N2, unsigned int nsteps, double nu, double delta, _Complex double (*g)(int,int), unsigned int print_freq);
// initialize vectors for computation
int ns_init_tmps( _Complex double **u, _Complex double ** tmp1, _Complex double **tmp2, _Complex double **tmp3, fft_vect* fft1, fft_vect *fft2, fft_vect *ifft, int K1, int K2, int N1, int N2);
// release vectors
int ns_free_tmps( _Complex double* u, _Complex double* tmp1, _Complex double *tmp2,_Complex double *tmp3, fft_vect fft1, fft_vect fft2, fft_vect ifft);
// initial value
int ns_init_u( _Complex double* u, int K1, int K2);
// next time step for Irreversible Navier-Stokes equation // next time step for Irreversible Navier-Stokes equation
int ins_step(_Complex double* u, ns_params params, fft_vects vects, _Complex double* tmp1, _Complex double* tmp2, _Complex double* tmp3); int ins_step( _Complex double* u, int K1, int K2, int N1, int N2, double nu, double delta, _Complex double (*g)(int,int), fft_vect fft1, fft_vect fft2,fft_vect ifft, _Complex double* tmp1, _Complex double *tmp2, _Complex double *tmp3);
// right side of Irreversible Navier-Stokes equation // right side of Irreversible Navier-Stokes equation
int ins_rhs(_Complex double* out, _Complex double* u, ns_params params, fft_vects vects); int ins_rhs( _Complex double* out, _Complex double* u, int K1, int K2, int N1, int N2, double nu, _Complex double (*g)(int,int), fft_vect fft1, fft_vect fft2, fft_vect ifft);
// compute alpha // compute alpha
_Complex double compute_alpha(_Complex double* u, ns_params params); _Complex double compute_alpha( _Complex double* u, int K1, int K2, _Complex double (*g)(int,int));
// get index for kx,ky in array of size S
int klookup( int kx, int ky, int S1, int S2);
#endif #endif