Flow does not support two phase flow. My best suggestion is to model the air as particles. I have done this specifically using small spheres which I gave teh attribute of polystyrene foam, or any other user defined solid that would have a density much less than water.
This will not compute any interaction that may exist in an actual water/air flow, because the particle calculation is done after the fluid flow is solved. But I think it works very well if you are investigating water/air separation.
Xinmiao:
Flow does not support two phase flow. My best suggestion is to model the air as particles. I have done this specifically using small spheres which I gave teh attribute of polystyrene foam, or any other user defined solid that would have a density much less than water.
This will not compute any interaction that may exist in an actual water/air flow, because the particle calculation is done after the fluid flow is solved. But I think it works very well if you are investigating water/air separation.