UDF in Fluent to Match Mass Flow at Pressure Outlet

Jonas Larsson

I'm running a case in Fluent where I need to match the outlet massflow to a certain given value. The outlet is a simple pressure outlet. Until now I have been doing this manually by iteratively adjusting the pressure until the massflow becomes correct. There must be a better way to do this automatically with a UDF (user defined function) in Fluent.

The UDF should compute the average outlet massflow and then adjust the outlet pressure based on Bernoulli to eventually obtain the right mass-flow. This could be done say every 100th iteration or so - not to often, that will be unstable.

Has anyone done this? I don't want to re-invent the wheel.

Thanks in advance!

The case btw is a fighter aircraft. I'm simulating the whole external flow including the air-intakes and the duct down to the engine inlet. The mass-flow I want to match is the engine inlet mass-flow.