[THK]

Hi there, I'm pretty new to CFD and this Forum. Actually, I'm doing my master thesis to optimize an extraction System. I've read a lot in this forum and it was a great help to understand fluent, but yet I haven't seen any advice for my current Problem.

In my System there are 8 inlets and 1 outlet. I only know the geometry and its dimensions and also the volume flow and pressure difference of the exaust fan at the outlet. The fluid is air. I assume the pressure at the outlet is the atmospheric pressure. I need to know the mass flows at the inlets. A Picture of the model is attached.

I modeled a quarter of the part and tried 3 combinations of BCs:

1) an negative velocity inlet at the outlet and pressure outlets at the inlets (I've read they can be used as free BC's).

2) pressure outlet with the known pressure difference at the outlet and pressure inlet at the inlets.

3) pressure outlet with target mass flow at the outlet and pressure inlet at the inlets.

In all three cases I got the same generel flow pattern but with very different values of velocity and pressure...

Now I'm wondering which combination could be the right. Do you have any advice?

Thanks for your help!