/
init.c
executable file
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/
init.c
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#include "helper.h"
#include "init.h"
/* ----------------------------------------------------------------------- */
/* Reading Parameters */
/* ----------------------------------------------------------------------- */
/**
* This operation initializes all the local variables reading a configuration
* file. For every variable a macro like READ_INT() is called passing it the
* input filename and the variable to be written to. This macro calls
* an operation read_int() augmenting the parameter set with the name of the
* variable to be read. The read_int() operation parses the input file, extracts
* the value of the variable, sets the variable and finally prints some debug
* information. This is possible as the macro adds the name of the variable to
* be set. All the helper operations can be found within helper.h and helper.c.
*
* @param szFileName char pointer to the filename
* @param Re Reynolds number
* @param UI initial velocity in x-direction - used by init_uvp()
* @param VI initial velocity y-direction - used by init_upv()
* @param PI initial pressure - used by init_upv()
* @param GX gravitation x-direction
* @param GY gravitation y-direction
* @param t_end end time (not discrete in time steps)
* @param xlength domain length x-direction
* @param ylength domain lenght y-direction
* @param dt time step length: dividing t_end by dt gives the number of
* time steps to perform. Actually dt is determined by a
* function, so manipulating this value within the
* configuration file should not affect the solution process
* at all
* @param dx cell length x-direction
* @param dy cell length y-direction
* @param imax number of cells in x-direction
* @param jmax number of cells in Y-direction
* @param alpha uppwind-differencing-factor alpha
* @param omg relaxation factor omega
* @param tau safety parameter for time step calculation
* @param itermax max. number of pressure iterations
* @param eps tolerance limit for pressure calculation
* @param dt_value time steps for output (after how many time steps one should
* write into the output file)
*/
int read_parameters(
const char *szFileName, /* name of the file */
double *Re, /* reynolds number */
double *UI, /* velocity x-direction */
double *VI, /* velocity y-direction */
double *PI, /* pressure */
double *GX, /* gravitation x-direction */
double *GY, /* gravitation y-direction */
double *t_end, /* end time */
double *xlength, /* length of the domain x-dir.*/
double *ylength, /* length of the domain y-dir.*/
double *dt, /* time step */
double *dx, /* length of a cell x-dir. */
double *dy, /* length of a cell y-dir. */
int *imax, /* number of cells x-direction*/
int *jmax, /* number of cells y-direction*/
double *alpha, /* uppwind differencing factor*/
double *omg, /* relaxation factor */
double *tau, /* safety factor for time step*/
int *itermax, /* max. number of iterations
for pressure per time step */
double *eps, /* accuracy bound for pressure*/
double *dt_value, /* time for output */
int *iproc,
int *jproc)
{
READ_DOUBLE( szFileName, *xlength );
READ_DOUBLE( szFileName, *ylength );
READ_DOUBLE( szFileName, *Re );
READ_DOUBLE( szFileName, *t_end );
READ_DOUBLE( szFileName, *dt );
READ_INT ( szFileName, *imax );
READ_INT ( szFileName, *jmax );
READ_DOUBLE( szFileName, *omg );
READ_DOUBLE( szFileName, *eps );
READ_DOUBLE( szFileName, *tau );
READ_DOUBLE( szFileName, *alpha );
READ_INT ( szFileName, *itermax );
READ_DOUBLE( szFileName, *dt_value );
READ_DOUBLE( szFileName, *UI );
READ_DOUBLE( szFileName, *VI );
READ_DOUBLE( szFileName, *GX );
READ_DOUBLE( szFileName, *GY );
READ_DOUBLE( szFileName, *PI );
READ_INT ( szFileName, *iproc );
READ_INT ( szFileName, *jproc );
*dx = *xlength / (double)(*imax);
*dy = *ylength / (double)(*jmax);
return 1;
}
/* ----------------------------------------------------------------------- */
/* Initializing U,V & P */
/* ----------------------------------------------------------------------- */
/**
* The arrays U,V and P are initialized to the constant values UI, VI and PI on
* the whole domain.
*/
void init_uvp(
double UI,
double VI,
double PI,
int il,
int ir,
int jb,
int jt,
double **U,
double **V,
double **P
)
{
int i;
int j;
for ( i = il-2 ; i<= ir+1; i++ )
{
for (j = jb-2; j<= jt+1; j++ )
{
if ( (i != il-2)&&(j != jb-2) ) {
U[i][j] = UI ;
V[i][j] = VI ;
P[i][j] = PI ;
}
else if (j != jb-2){
U[i][j] = UI ;
}
else if (i != il-2){
V[i][j] = VI ;
}
}
}
}