[demichie]

Hi all,
I am trying to simulate the rise of gas and liquid in a vertical conduit with twoPhaseEulerFoam. The liquid phase has a high visocsity (1 Pa.s).
When the gas is reaching the outlet at the top I would like to see the "bubble" exiting from the conduit. The problem is the when it reach the exit the head of the bubble is distorted and it seems to open. At the same time horizontal components of the velocities develop.
In a short time the courant number becomes too large.
At the outlet I have used a fixedValue for the pressure (atmospheric), zeroGradient for the velocities, and inletOutlet for the gas volume fraction.
What are the right boundary conditions to have the gas exiting from the conduit without problems?

Thank you
Mattia