Outlet pressure for compressible flow

Michelle

Hi everyone,

I'm only a new user of CFX. I want to simulate compressible multiphase flow (saturated vapor and saturated liquid). I know their inlet pressure(400kPa) and inlet velocities, however i don't know anything about the outlet condition (in reality, the outlet flows through another device, not exposed to atmosphere). I tried simulating using Pref=1atm, Pout(average static)=0atm, and inlet velocities for the fluids. The results for the velocities are ok, but the values of pressure are almost all negative and as expected the results for densities are lower. However, the shape of the profile especially for static pressure is as expected. Is this results reliable? Meaning can I just add a constant to the results such that the pressure at inlet will be 400kPa? Can I use this adjusted pressure data to correct the values for density?

I've read that it is not an issue for incompressible flow because the important thing is the pressure difference but I'm really trapped on how to set the outlet condition for compressible flow.

Any help is much appreciated! Thanks a lot!

Michelle