[Jinfeng]

Hi folks,

I wrote a program to calculate the electrical body force with DEFINE_SOURCE macro. Inside the macro, C_CENTROID was used to get the coordinates of the cells (just like the DEFINE_SOURCE example in UDF manual). However, when I try to interpret the code, it gives me an error saying "line 13 C_CENTROID undeclared variable."

I can't figure out why it threw me that error! Does anybody know what's going on? Any help would be greatly appreciated! Thanks.

The following code is the DEFINE_SOURCE part:

#include "udf.h"

DEFINE_SOURCE(xmom_source, c, t, dS, eqn)
{
int i; // index for the nodes
float startx; // x coordinate of nearest node to interpolation node with lower x value
float starty; // y coordinate of nearest node to interpolation node with lower y value
float startz; // z coordinate of nearest node to interpolation node with lower z value
float xinterpfact, yinterpfact, zinterpfact;
float newrho;
float newdvdx, newdvdy, newdvdz;
float xinterp1, xinterp2, xinterp3, xinterp4;
float yinterp1, yinterp2;
real x[ND_ND];
real source;


C_CENTRIOD(x,c,t);

xinc = xdomain/(xdirnodes-1);
yinc = ydomain/(ydirnodes-1);
zinc = zdomain/(zdirnodes-1);
startx = ((int)(x[0]/xinc))*xinc;
xinterpfact = (x[0] - startx)/xinc;
starty = ((int)(x[1]/yinc))*yinc;
yinterpfact = (x[1] - starty)/yinc;

startz = ((int)(x[2]/zinc))*zinc;
zinterpfact = (x[2] - startz)/zinc;

i = xdirnodes*ydirnodes*startz/zinc + xdirnodes*starty/yinc + startx/xinc;

//*** INTERPOLATE RHO ***//
xinterp1 = xinterpfact*(rho[i+1]-rho[i]) + rho[i];
xinterp2 = xinterpfact*(rho[i+xdirnodes+1]-rho[i+xdirnodes])+rho[i+xdirnodes];
xinterp3 = xinterpfact*(rho[i+xdirnodes*ydirnodes+1]-rho[i+xdirnodes*ydirnodes])+rho[i+xdirnodes*ydirnodes];
xinterp4 = xinterpfact*(rho[i+xdirnodes+xdirnodes*ydirnodes+1]-rho[i+xdirnodes+xdirnodes*ydirnodes])+rho[i+xdirnodes+xdirnodes*ydirnodes];

yinterp1 = yinterpfact*(xinterp2-xinterp1)+xinterp1;
yinterp2 = yinterpfact*(xinterp4-xinterp3)+xinterp3;

newrho = zinterpfact*(yinterp2-yinterp1)+yinterp1;

//*** INTERPOLATE DVDX ***//
xinterp1 = xinterpfact*(dvdx[i+1]-dvdx[i]) + dvdx[i];
xinterp2 = xinterpfact*(dvdx[i+xdirnodes+1]-dvdx[i+xdirnodes])+dvdx[i+xdirnodes];
xinterp3 = xinterpfact*(dvdx[i+xdirnodes*ydirnodes+1]-dvdx[i+xdirnodes*ydirnodes])+dvdx[i+xdirnodes*ydirnodes];
xinterp4 = xinterpfact*(dvdx[i+xdirnodes+xdirnodes*ydirnodes+1]-dvdx[i+xdirnodes+xdirnodes*ydirnodes])+dvdx[i+xdirnodes+xdirnodes*ydirnodes];

yinterp1 = yinterpfact*(xinterp2-xinterp1)+xinterp1;
yinterp2 = yinterpfact*(xinterp4-xinterp3)+xinterp3;

newdvdx = zinterpfact*(yinterp2-yinterp1)+yinterp1;

source = newrho*newdvdx;
dS[eqn] = 0.0;

return source;
}