domain or zone?

kevin

1,what's the difference among domain and zone and interior?

2,i'm simulating fluid structure interaction(FSI) by using sliding meshes and DEFINE_CG_MOTION, and the dynamic meshes include three parts(one interior, two interfaces), exciting force is accessed by computing lift on wall by looping through all faces, then how can i get the face thread of wall? wall's ID is 7, ID of the interior (one of whose boundary is the wall) is 2, but the following cods fail: domain = Get_Domain(2); thread = Lookup_Thread(domain, 7);

i also try: t = DT_THREAD ((Dynamic_Thread *)dt); //dt is the three dynamic meshes passed by DEFINE_CG_MOTION domain = THREAD_DOMAIN(t); thread = Lookup_Thread(domain, 7); fail again!

would anyone give me any kind of suggestion? THANX IN ADVANCE!