UDF for DPM
 

I am trying to calculate lagrangian blood damage by using DPM in Fluent. So, to calculate the degree of blood damage on a particle, I'd need to integrate shear stress on the particle (^exponent) w.r.t (residence) time. When I use the UDF below, I am getting a value of 0. I even tried replacing the values of C_MU_L and C_R with the actual numbers since they are constant throughout the domain.

I am a beginner in Fluent UDF programming and sincerely appreciate any suggestions/help towards getting this UDF right.

#include "udf.h"


#define A *****
#define exp_t ****
#define exp_tau ***

DEFINE_DPM_SOURCE(calc_HIp, c, t, dS, eqn)
{
real tau = C_STRAIN_RATE_MAG(c,t)*(C_MU_L(c,t));
real source = pow(A,1.0/exp_t)*pow(tau,exp_tau/exp_t)*C_R(c,t);

dS[eqn] = 0.;

return source;
}

Thanks in advance