Dear ArraynI tried both pressure outlet and mass flow outlet BCs.nMass flow outlet: the pressure in the tank goes up to unphysically high valuesnPressure outlet: the outlet mass flow rate becomes positive and almost 10 times more than the inlet flow. Also the form of the VF contour seems strange and unphysical. please find it below after some time steps (TS = 0.01 s)nP.S: I set one mass trasnfer mechanism (evaporation-condensation) to model both evaporation and condensation in the tank to find the equilibrium state. I found in the User guide that From must be the liquid and To must be the gas phase so I assume one mass transfer mechanism can model both evaporation and condensation at the interface.nPlease let me know for any tips! nThank you in advance, best regards.nn