find a cell from its centroid coordinates
 

Dear all,

Does anyone know how to find a cell when its centroid coordinates are known ?
I have the coordinates x[0] and x[1], and I want to find the corresponding cell in my UDF

Thank's a lot

Hi Annan;

Here is how I would do it. I hope it gives you the idea.

real a,b;
int i;
real x[N_D];

begin_c_loop (c,t)
{
C_CENTEROID(x,c,t);
if(x[0]>a-0.00001 && x[1]>b-0.00001 && x[0]<a+0.00001 && x[1]<b+0.00001) // a and b are the coordinate values
{
i=c;
}
}
end_c_loop(c,t)

I dont know if the +-0.000001 (just a small value) would be able sufficient to find the cell you can work on it for your case. Ansys gives error if commands have real=real.

In the end the integer "i" will be the number of the cell you are looking for.

Best Regards,
Doruk

Hi Annan,

doruk's solution should work (in serial and 2D, but easily fixed to work in 3D). It is currently only a sketch -- for example, you would probably want a thread loop for all values of t. But this is clearly an O(N) process, where N is the number of cells.

A more efficient algorithm is available built-in, but the syntax is slightly fiddly and version-dependent -- google for CX_Find_Cell_With_Point, for example https://www.cfd-online.com/Forums/fl...t-problem.html.

Good luck!
Ed