Two-phases Flow in a PEM Electrolyzer

Hello everyone,

I am trying to model a proton exchange membrane water electrolyzer in comsol (2D model) to have the void fraction mixture flows (Oxygen+Water).
For that I use the Bubble flow model of Comsol.

I would like to include the material porosity in the conservation equations (mass and momentum).

Could you tell me if it is possible ? And how ?

Best regards