Force flow direction
 

I'd like to ask:
I have air flow in duct through heat exchanger which is randomly oriented. Is it possible to force flow direction in region to simulate heat exchanger without modeling his detail geometry?

you can force the air to go in one direction by specifying the porous coefficients appropriately. Use actual value in the flow direction and about 100-1000 times larger value in the other directions.

Thank you very much. This is exactly what i need.