Bubble column simulation
 

I want to simulate a bubble column consisting of air and water. I have created the 3D geometry of column, meshed it, selected the Eulerian model, specified the materials and phases but I am struggling with the boundary conditions. I am able to specify the inlet and oulet conditions (velocity and pressure) of both water and air but when I select "gas phase" for the inlet/outlet condition for air, the programme changes all the boundary conditions to gas phase and when I select "liquid phase" for inlet/outlet condition of water it changes all the boundary conditions to liquid phase. I cannot specify the phases for the boundary conditions.

Is there something that I am doing wrong:confused: