Initial commit
This commit is contained in:
Ian Jauslin
282
src/main.c
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282
src/main.c
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#define VERSION "0.0"
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#include <math.h>
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#include <complex.h>
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#include <fftw3.h>
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#include <string.h>
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#include <stdlib.h>
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#include "navier-stokes.h"
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// usage message
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int print_usage();
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// read command line arguments
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int read_args(int argc, const char* argv[], ns_params* params, unsigned int* nsteps, unsigned int* computation_nr);
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// compute enstrophy as a function of time in the I-NS equation
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int enstrophy(ns_params params, unsigned int Nsteps);
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#define COMPUTATION_ENSTROPHY 1
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int main (int argc, const char* argv[]){
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ns_params params;
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unsigned int nsteps;
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int ret;
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unsigned int computation_nr;
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// default computation: phase diagram
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computation_nr=COMPUTATION_ENSTROPHY;
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// read command line arguments
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ret=read_args(argc, argv, ¶ms, &nsteps, &computation_nr);
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if(ret<0){
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return(-1);
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}
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if(ret>0){
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return(0);
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}
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// enstrophy
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if(computation_nr==COMPUTATION_ENSTROPHY){
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enstrophy(params, nsteps);
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}
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return(0);
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}
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// usage message
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int print_usage(){
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fprintf(stderr, "usage:\n nstrophy enstrophy [-h timestep] [-K modes] [-v] [-N nsteps]\n\n nstrophy -V [-v]\n\n");
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return(0);
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}
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// read command line arguments
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#define CP_FLAG_TIMESTEP 1
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#define CP_FLAG_NSTEPS 2
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#define CP_FLAG_MODES 2
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#define CP_FLAG_NU 3
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int read_args(int argc, const char* argv[], ns_params* params, unsigned int* nsteps, unsigned int* computation_nr){
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int i;
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int ret;
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// temporary int
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int tmp_int;
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// temporary unsigned int
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unsigned int tmp_uint;
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// temporary double
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double tmp_double;
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// pointers
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char* ptr;
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// flag that indicates what argument is being read
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int flag=0;
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// print version and exit
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char Vflag=0;
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// defaults
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/*
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params->h=6.103515625e-05;
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params->K=16;
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*nsteps=16777216;
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params->nu=4.9632717887631524e-05;
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*/
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params->h=1e-5;
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params->K=16;
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*nsteps=10000000;
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params->nu=1e-4;
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// loop over arguments
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for(i=1;i<argc;i++){
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// flag
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if(argv[i][0]=='-'){
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for(ptr=((char*)argv[i])+1;*ptr!='\0';ptr++){
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switch(*ptr){
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// timestep
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case 'h':
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flag=CP_FLAG_TIMESTEP;
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break;
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// nsteps
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case 'N':
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flag=CP_FLAG_NSTEPS;
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break;
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// modes
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case 'K':
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flag=CP_FLAG_MODES;
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break;
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// friction
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case 'n':
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flag=CP_FLAG_NU;
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break;
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// print version
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case 'V':
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Vflag=1;
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break;
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default:
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fprintf(stderr, "unrecognized option '-%c'\n", *ptr);
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print_usage();
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return(-1);
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break;
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}
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}
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}
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// timestep
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else if(flag==CP_FLAG_TIMESTEP){
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ret=sscanf(argv[i],"%lf",&tmp_double);
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if(ret!=1){
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fprintf(stderr, "error: '-h' should be followed by a double\n got '%s'\n",argv[i]);
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return(-1);
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}
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params->h=tmp_double;
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flag=0;
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}
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// nsteps
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else if(flag==CP_FLAG_NSTEPS){
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ret=sscanf(argv[i],"%u",&tmp_uint);
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if(ret!=1){
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fprintf(stderr, "error: '-N' should be followed by an unsigned int\n got '%s'\n",argv[i]);
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return(-1);
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}
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*nsteps=tmp_uint;
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flag=0;
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}
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// nsteps
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else if(flag==CP_FLAG_MODES){
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ret=sscanf(argv[i],"%d",&tmp_int);
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if(ret!=1){
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fprintf(stderr, "error: '-K' should be followed by an int\n got '%s'\n",argv[i]);
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return(-1);
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}
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params->K=tmp_uint;
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flag=0;
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}
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// friction
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else if(flag==CP_FLAG_TIMESTEP){
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ret=sscanf(argv[i],"%lf",&tmp_double);
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if(ret!=1){
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fprintf(stderr, "error: '-n' should be followed by a double\n got '%s'\n",argv[i]);
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return(-1);
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}
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params->nu=tmp_double;
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flag=0;
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}
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// computation to run
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else{
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if(strcmp(argv[i], "enstrophy")==0){
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*computation_nr=COMPUTATION_ENSTROPHY;
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}
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else{
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fprintf(stderr, "error: unrecognized computation: '%s'\n",argv[i]);
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print_usage();
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return(-1);
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}
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flag=0;
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}
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}
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// print version and exit
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if(Vflag==1){
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printf("nstrophy " VERSION "\n");
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return(1);
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}
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return(0);
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}
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// compute enstrophy as a function of time in the I-NS equation
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int enstrophy(ns_params params, unsigned int Nsteps){
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_Complex double* u;
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_Complex double* tmp1;
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_Complex double* tmp2;
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_Complex double* tmp3;
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_Complex double alpha;
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_Complex double avg;
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unsigned int t;
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int kx,ky;
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fft_vects fft_vects;
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// sizes
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params.S=2*params.K+1;
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params.N=4*params.K+1;
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// velocity field
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u=calloc(sizeof(_Complex double),params.S*params.S);
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params.g=calloc(sizeof(_Complex double),params.S*params.S);
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// allocate tmp vectors for computation
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tmp1=calloc(sizeof(_Complex double),params.S*params.S);
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tmp2=calloc(sizeof(_Complex double),params.S*params.S);
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tmp3=calloc(sizeof(_Complex double),params.S*params.S);
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// initial value
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for(kx=-params.K;kx<=params.K;kx++){
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for(ky=-params.K;ky<=params.K;ky++){
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//u[KLOOKUP(kx,ky,params.S)]=kx*kx*ky*ky*exp(-(kx*kx+ky*ky));
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if((kx==1 && ky==0) || (kx==-1 && ky==0)){
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u[KLOOKUP(kx,ky,params.S)]=1;
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}
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else{
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u[KLOOKUP(kx,ky,params.S)]=0;
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}
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}
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}
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// driving force
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for(kx=-params.K;kx<=params.K;kx++){
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for(ky=-params.K;ky<=params.K;ky++){
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//params.g[KLOOKUP(kx,ky,params.S)]=sqrt(kx*kx*ky*ky)*exp(-(kx*kx+ky*ky));
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if((kx==2 && ky==-1) || (kx==-2 && ky==1)){
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params.g[KLOOKUP(kx,ky,params.S)]=1;
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}
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else{
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params.g[KLOOKUP(kx,ky,params.S)]=0;
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}
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}
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}
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// prepare vectors for fft
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fft_vects.fft1=fftw_malloc(sizeof(fftw_complex)*params.N*params.N);
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fft_vects.fft1_plan=fftw_plan_dft_2d((int)params.N,(int)params.N, fft_vects.fft1, fft_vects.fft1, FFTW_FORWARD, FFTW_MEASURE);
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fft_vects.fft2=fftw_malloc(sizeof(fftw_complex)*params.N*params.N);
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fft_vects.fft2_plan=fftw_plan_dft_2d((int)params.N,(int)params.N, fft_vects.fft2, fft_vects.fft2, FFTW_FORWARD, FFTW_MEASURE);
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fft_vects.invfft=fftw_malloc(sizeof(fftw_complex)*params.N*params.N);
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fft_vects.invfft_plan=fftw_plan_dft_2d((int)params.N,(int)params.N, fft_vects.invfft, fft_vects.invfft, FFTW_BACKWARD, FFTW_MEASURE);
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// init running average
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avg=0;
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// iterate
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for(t=0;t<Nsteps;t++){
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ins_step(u, params, fft_vects, tmp1, tmp2, tmp3);
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alpha=compute_alpha(u, params);
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// to avoid errors building up in imaginary part
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for(kx=-params.K;kx<=params.K;kx++){
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for(ky=-params.K;ky<=params.K;ky++){
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u[KLOOKUP(kx,ky,params.S)]=__real__ u[KLOOKUP(kx,ky,params.S)];
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}
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}
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// running average
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if(t>0){
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avg=avg-(avg-alpha)/t;
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}
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if(t>0 && t%1000==0){
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fprintf(stderr,"%8d % .8e % .8e % .8e % .8e\n",t, __real__ avg, __imag__ avg, __real__ alpha, __imag__ alpha);
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printf("%8d % .8e % .8e % .8e % .8e\n",t, __real__ avg, __imag__ avg, __real__ alpha, __imag__ alpha);
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}
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}
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// free memory
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fftw_destroy_plan(fft_vects.fft1_plan);
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fftw_destroy_plan(fft_vects.fft2_plan);
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fftw_destroy_plan(fft_vects.invfft_plan);
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fftw_free(fft_vects.fft1);
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fftw_free(fft_vects.fft2);
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fftw_free(fft_vects.invfft);
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free(tmp3);
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free(tmp2);
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free(tmp1);
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free(params.g);
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free(u);
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return(0);
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}
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