[DmitryS]

Hello, dear colleagues.

There is a problem, to simulate flow a two-phase fluid (air-water) under pressure drop in a circular horizontal pipe plus gravity. I need to define the parameters (heat transfer coefficients and resistance) at two parts of the pipe (wet and dry) and at the phase boundary. The best is to get a steady flow. Flow regime and the level of liquid in the pipe suggest almost waveless flow (we can assume the phase boundary is a plane).

I have some thoughts and questions:

1) In the formulation of the problem is a point that flow going under pressure drop. How to set the static pressure at the inlet of the pipe, if the standard BC has only the total pressure?

2) Is it possible to solve this problem, considering these simplifications, in stationary formulation? If yes, which model to use.

3) If the problem can not be solved in a stationary formulation and have to use the VOF model. How to simplify the task? Solve the flow in pipe long 50 calibers for getting a steady flow is not a good solution.

Thanks!