need help for UDF
 

Hello everybody

I'm trying to increase the particle size (diameter) with UDF in fluent. I made a little code for testing purposes and interpreted it and then defined an injection single which uses this UDF. But when I dislay particle track, the diameter doesn't change. If someone could help me it would be great.
This is my code:

/* compute new particle diameter */
#include "udf.h"

DEFINE_DPM_LAW(diam_particle,p,ci)
{
P_DIAM(p) = 6.0*pow((0.015*0.0003*P_POS(p)[0]/(2*0.7*1000.0*9.81)),(1/3));
}