interior and internal faces
 

Hi, all,

I am wondering what is the difference between INTERNAL_FACE and INTERIOR_FACE?

In $FLUENT.INC/fluent6.1/src/threads.h are their definitions:

#define INTERNAL_FACE_THREAD_P(t)(THREAD_FLAGS(t) & THREAD_FL_INTERNAL_FACE)

#define INTERIOR_FACE_THREAD_P(t)(INTERNAL_FACE_THREAD_P(t ) && THREAD_T0(t) == THREAD_T1(t))

But, I can't figure out how THREAD_T0(t) probably equal to THREAD_T1(t). In what situation are these two cell threads the same? Consequently I don't understand what an interior face is. Help needed please!

Thanks,