[Shoh]

HI, I have a problem in calculating the area of an interior face (NOT boundary face).
Here, boundary face means that the face lies at domain boundary
but the interior face is in the domain.

I wrote a code for the calculation of face area:

#include "udf.h"
DEFINE_ON_DEMAND(ingression)
{
Domain *d = Get_Domain(1);
Thread *tf;
face_t f;

real sumarea;
real A[ND_ND];

int nid=12;
tf = Lookup_Thread(d,nid);

sumarea=0.0;

begin_f_loop(f,tf)
{
F_AREA(A,f,tf);
sumarea+=NV_MAG(A);
}
end_f_loop(f,tf)

Message("**** netarea = %f ****\n",sumarea);
}

This code works if the face of interest (nid) is boundary face but not for the interior face (e.g. nid=12).

How can I overcome this problem??
Thanks,