UDF for granular flow
 

Hello, I run a simulation for granular flow and used the non-spherical drag model and everything went fine.
I tried then adding a UDF to see the effect of the aspect ratio and angle of attack but I had this error floating point exception: pressure correction
here is my UDF

#include "udf.h"
#include "cstdlib"
#include "cmath"
#include "ctime"
#include "iostream"
#define pi 3.14



DEFINE_DPM_DRAG(particle_drag_force,Re,p)
{
cell_t c = P_CELL(p);
Thread *t = P_CELL_THREAD(p);


real mu_g;
real cd;
real particle_drag_force;
real cw_sp;
real sph;
real diam_cy;
real a_s_s;
real a_cs;
real v;
real l;
real a_s_c;
real cw_sec;
real teta;
real r;
real ar;
real diam_eq;
/*-----------------------------------------------------------------*/

mu_g = C_MU_L(c,t);
diam_eq = P_DIAM(p);

/*------------------------------------------------------------------*/
/*compute equivilant diameter using gaussian function to generate random number*/

float sigma = 1.0;
float Mi = 1.0;

srand(time(0));
float v1= ( (float)(rand()) + 1. )/( (float)(RAND_MAX) + 1. );
float v2= ( (float)(rand()) + 1. )/( (float)(RAND_MAX) + 1. );

ar = ((cos(2*3.14*v2)*sqrt(-2.*log(v1)))*sigma+Mi)*15;

/*gaussian function to generate random number*/
sigma = 1.0;
Mi = 1.0;

srand(time(0));
float v3= ( (float)(rand()) + 1. )/( (float)(RAND_MAX) + 1. );
float v4= ( (float)(rand()) + 1. )/( (float)(RAND_MAX) + 1. );

r = (cos(2*3.14*v4)*sqrt(-2.*log(v3)))*sigma+Mi;


/*compute teta*/
teta = 20.* r;

a_s_s = pi*diam_eq*diam_eq;
a_cs = a_s_s/4.;
v = 4.*diam_eq*diam_eq*diam_eq/3.;
diam_cy = pow((4.*v/pi/ar), 1/3);
l = ar*diam_cy;
a_s_c = (pi*pow(diam_cy, 2.)/2.)+(pi*diam_cy*l);
sph = a_s_s/a_s_c;
cw_sec = ((pi*pow(diam_cy, 2.)/4)*cos(teta*pi/180))+(diam_cy*l*sin(teta*pi/180));
cw_sp = a_cs/cw_sec;
/*------------------------------------------------------------------*/
/*compute Cd*/
cd = (8./(Re*sqrt(cw_sp)))+(16./(Re*sqrt(sph)))+(3./(pow(sph, 0.75)*sqrt(Re)))+((0.42*pow(10, 0.4*pow(-log10(sph), 0.2)))/(cw_sp));
particle_drag_force = 18*cd*Re/24;
return (particle_drag_force);
}

I had no problems compiling the UDF.
Is the problem with the UDF? controls? mesh?
Thanks in advance