[mrwts]

Hi everybody, I am new in Fluent and UDF programming and I have got some troubles trying to create a simple UDF code.
I am working with an energy source, whose position is time-dependent. Using simple functions, I determine the source position in x and y. But, I need to compare that position with the cell centroid.
Which Macro Access Data should I use to get (or identify that specific cell, that cointains my source position point)?
Knowing the source position, my code goes like:

begin_c_loop(c,t)
{
C_CENTROID(x_c,c,t);
C_CENTROID(y_c,c,t);
w = x_c[1];
if (pow((w-SOURCE_X_POSITION),2)+pow((w-SOURCE_Y_POSITION),2) < pow(r,2))
{
double V = 3.1415*pow(r,2);
source = power/V;
dS[eqn] = 0;
}
else
{
source = 0;
dS[eqn] = 0;
}
return source;
}
end_c_loop(c, c_thread)

Somehow, I need the program to identify which specifics cell has to be compared with the source position. So it's basically: Identifying cell, which contains the source position, comparing its centroid with the source position and calculating the source power.

Thanks in advance