Hi, I am using Star CCM+ to model the air flow through a racing car's airbox (intake system), and would like to know what boundary conditions to use. (1 inlet and 1 outlet)

The flow is compressible (ideal gas), and I have data for pressure, mass flow and velocity at the outlet port.

I have no data for inlet, except that atm pressure is assumed.

If you need any more info let me know, any help would be much appreciated.

Thanks.

what about trying stagnation pressure ?

outlet boundary is not good for any compressible flow because you leave the code free to set any pressure level. You must fix pressure level somewhere in the domain at a boundary.