boundary condition for centrifugal fan

vishal

Dear Friends,

I am simulating building car parking ventilating system. I have centrifugal jet fan to force the polluted air outside through exhaust fan.

I am getting difficulty for giving BC to centrifugal fan.Also how should I model it in my domain?whether i have to give inlet bc and outlet bc to 2 faces and remaining 4 faces as wall both or only inlet/outlet to one face and 5 sides as wall. If anybody already working on ventilation ,plz suggest.

Thanks in advance