please help me with this special kind of boundary condition.
 

I do a simulation on some kind of gas-liquid separator. there are two outlet and one of them is submerged in the liquid. that means only liquid can flow out and gas can not. how should I deal with this boundary condition, which kind of boundary should be selected? thanks!

Are you using a VOF model to solve this? If so at the outlet which is submerged in a liquid, you can specify the volume fraction of the liquid to be 1.0.

I have already used Euler multiphase model, VOF can not be turn on. so I try to find other measure to realize such condition. I have ever had a idea that adding porous media at one of outlet, but in star-cd porous media and euler model cannot co-exist either. now I wonder whether subroutine can realize this condition. Do you have experience of dealing with a similiar condition ? thank you!

I have used STAR CCM+ for a similar application. It was an analysis where I was looking at a pool of water that was being drained off due to the air blowing above it. However in the same simulation I had a porous media upstream of this pool of liquid. Sorry, I've not had a chance to try it with STAR CD.

thank you very much. Maybe I can try it with STAR-CCM+.