[morihangi]

Hi every one,
I ma trying to write a UDF to calculate the surface integral the interface between two zones, and then used the calculated value as a source term for one of the zones. In other words, my source term is a function of surface integral at the interface. in other words, I want to calculate a specific function on the C0 cells adjacent to the interface, then the values are supposed to be summed and the final value will be used in the source term. below is the UDF I wrote and I was able to compile it without any error. But every time I activate the source term, I receive the segmentation fault which means that there is something in the UDF that the solver does not have access to.
I would be grateful if anyone can help me with this.

#include "udf.h"
#include "mem.h"
DEFINE_ADJUST(interface_integral, domain)
{

face_t f; /* Index that identifies a face. */
real T; /* cell temperature */
real vx; /* x component of velocity */
real vy; /* y component of velocity */
real vz; /* z component of velocity */
real rho; /* density */
real cp; /* specific heat */
int ID = 11; /* retreiving interface by Zone ID assigned fluent GUI */
real firstterm;
real surfaceinteg=0.; /* initial value of surface integral before loop */
cell_t c, c0;
Thread t, *tf, *t0;
tf = Lookup_Thread(domain, ID);
c0=F_C0(f, tf);
begin_f_loop(f, tf)
{
t0 = THREAD_T0(tf);
T=C_T(c0,t0);
rho=C_R(c0,t0);
cp=C_CP(c0,t0);
vx=C_U(c0,t0);
vy=C_V(c0,t0);
vz=C_W(c0,t0);
firstterm=rho*cp*T*((vx)+(vy)+(vz));
surfaceinteg +=firstterm;
}
end_f_loop(f, tf)

begin_f_loop(f,tf)
{
F_UDMI(f,tf,1) = surfaceinteg;
}
end_f_loop(f,t)
}
/* end of define_adjust */
DEFINE_SOURCE(energy_source, c, t, dS, eqn)
{
real source, surfaceinteg;
face_t f; /* Index that identifies a face. */
Thread *tf;
surfaceinteg=F_UDMI(f,tf,1);
source=(1/(C_VOLUME(c, t)))*surfaceinteg;
dS[eqn] =0.0;
return source;
}