outlet boundary condition for two-phase flow
 

Hi everybody,

I'm simulating a free surface vortex with Fluent using the VOF model.
My domain is a square box with mass flow inlet b.c. for the liquid phase and outflow b.c. at the outlet (in order to take into account the gas entrainment phenomena)

My problem is that, if I want to simulate the emptying of the box, i need a pressure inlet for the air at the top of the box, so I cannot use anymore the outflow b.c.

Which outlet boundary condition do you suggest me to use?

Thank you in advance,

Andrea