[Ahmed_Ali]

Good morning everybody, I want to ask a confusing question that confuses me a lot. In the pressure outlet boundary condition, is the entered pressure is the exit pressure or the back pressure??
I already know that they are the same except for under expanded nozzles and it depends on the flow whether it is subsonic or supersonic, but if the flow is partially supersonic due to separation and other factors, what pressure value should I enter??
Thanks in advance for your help.