Object in room with that object being the purpose of investigation
 

Hi, forgive me if this is an awfully simple question but I really have no clue here. Is it possible to model a bigger room with a smaller room in it? The purpose is to have inlet and outlet on the bigger room and investigate the temperature diff IN the smaller room after applying certain BCs to the walls of the smaller room. From what I have found, it is only possible to create "obstacles" in a room by means of subtracting. When that is done, I can only get results from the flow in the bigger room, while I'm trying to get results from the smaller room. I hope you guys understand what I'm trying to explain here and sure hope someone can guide me on this. So, anyone?

Can you post a sketch of what you want

http://img27.imageshack.us/img27/2739/sketchlz.png

Uploaded with ImageShack.us

that's what I can come up with with my current resources as I haven't got access to a better program other than paint. So forgive the sketch but it should give you a clearer idea of what I'm trying to achieve.

just split outer volume with inner volume.
Then be aware, that a split generates surfaces which will be treated as interior.
So if you need wall instead of interior, you need to define them as wall in the BC panel