[SCoss]

I am attempting to use SOLIDWORKS flow simulation to simulate the airflow through a ram air duct. Think like a venturi tube on an airplane, but the convergent divergent duct is embedded in the structure rather than being a protrusion. The issue I'm having, is that for the area ratio of the entrance to the throat, I don't get the velocities I expect at the throat when doing an external flow sim. When I build just the duct itself and put lids on it and do an internal sim I get the numbers I expect. Is there any deficiency in the Flow Simulation when using the external simulation and the flow must through a completely bounded flow area? Or is the simulation giving me true results and the flow through the duct is that degraded by being embedded in the larger structure moving through the air?