void calculate_fg(double Re, double GX, double GY,double alpha, double dt,double dx,double dy, int imax, int jmax,
double **U,double **V,double **F,double **G, int **Flag)
{
/* see formulas 9 and 10 in combination with formulas 4 and 5 */
int i;
int j;
for (j = 1; j <= jmax; j++)
for (i = 1; i <= imax; i++)
{
/********** calculate F **********/
/* calculate f and g only between two fluid cells */
if ((i <= imax - 1) && (Flag[i+1][j] == C_F && Flag[i][j] == C_F))
{
F[i][j] = U[i][j] + dt * (
/* 1/Re * (d²u/dx² + d²u/dy²) */
1 / Re * (d2udx2(i, j, U, dx) + d2udy2(i, j, U, dy))
/* - du²/dx */
- du2dx(i, j, U, dx, alpha)
/* - duv/dy */
- duvdy(i, j, U, V, dy, alpha) + GX);
}
else
/* F aus 1.4 bis 1.6 */
F[i][j] = U[i][j];
/********** calculate G **********/
if ((j <= jmax - 1) && (Flag[i][j+1] == C_F && Flag[i][j] == C_F))
{
G[i][j] = V[i][j] + dt * (
/* 1/Re * (d²v/dx² + d²v/dy²) */
1 / Re * (d2vdx2(i, j, V, dx) + d2vdy2(i, j, V, dy))
/* - duv/dx */
- duvdx(i, j, U, V, dx, alpha)
/* - dv²/dy */
- dv2dy(i, j, V, dy, alpha) + GY);
}
/* G aus 1.4 bis 1.6 */
else
G[i][j] = V[i][j];
}
/* calculate boundary values - see formula 17 */
for (j = 1; j <= jmax; j++)
{
F[0][j] = U[0][j];
F[imax][j] = U[imax][j];
}
for (i = 1; i <= imax; i++)
{
G[i][0] = V[i][0];
G[i][jmax] = V[i][jmax];
}
}
void calculate_fg(
double Re,
double GX,
double GY,
double alpha,
double dt,
double dx,
double dy,
int imax,
int jmax,
double **U,
double **V,
double **F,
double **G,
int **Flag
){
int i,j;
/* boundary conditions */
for(j=1; j<=jmax; j++){
F[ 0 ][ j ] = U[ 0 ][ j ];
F[ imax ][ j ] = U[ imax ][ j ];
}
for(i=1; i<=imax; i++){
G[i][0] = V[i][0];
G[i][jmax] = V[i][jmax];
}
/* inner values */
for(i=1; i<=imax-1; i++)
for(j=1; j<=jmax; j++)
if(Flag[i][j]==C_F && Flag[i+1][j]==C_F)
F[i][j] = U[i][j] + dt * (
(d2dx(U,i,j,dx) + d2dy(U,i,j,dy))/Re - du2dx(U, i, j, dx, alpha) - duvdy(U,V,i,j,dy, alpha) + GX
);
for(i=1; i<=imax; i++)
for(j=1; j<=jmax-1; j++)
if(Flag[i][j]==C_F && Flag[i][j+1]==C_F)
G[i][j] = V[i][j] + dt * (
(d2dx(V,i,j,dx) + d2dy(V,i,j,dy))/Re - duvdx(U, V, i, j, dx, alpha) - dv2dy(V,i,j,dy, alpha) + GY
);
}