[hoangtugugu]

I have an issue on computing pressure force in multiphase (2 phases) problem. The result which is compute by my udf doesn't match with the FLUENT Reports. It's smaller and i don't know why? This is my UDF:

#include "udf.h"

DEFINE_EXECUTE_AT_END(force_calculation)
{
double NV_VEC(A);
double NV_VEC(pressure), NV_VEC(total_pressure);
double Area = 0.0, ftp;

Domain *d = Get_Domain(1);
Thread *f_th;
face_t f;
int ID = 18;

NV_S(total_pressure,=,0.0);

d = Get_Domain(1);
f_th = Lookup_Thread(d,ID);

begin_f_loop(f,f_th)
{
F_AREA(A,f,f_th);
Area += NV_MAG(A)*2*M_PI;

NV_VS(pressure,=,A,*,F_P(f,f_th));

pressure[0] = 2*M_PI*pressure[0];
pressure[1] = 0.0;

NV_V(total_pressure,+=,pressure);
}
end_f_loop(f,f_th)

ftp = total_pressure[0];

Message("\nTotal Area = %.7e (m2)\n",Area);
Message("Pressure_force = %.9f (N)\n",ftp);
}

Thanks for viewing and replying!