Boundary codition for multiphase

Nima Sheyad

Hi everybody I'm trying to simulate a two phase flow. The problem is condensation of a turbulent annular film of R-22 vapor in a tube. I've used Fluent 5.23 to solve the problem but I haven't known how to enter some boundary conditions. The VOF two multiphase model has used for simulating the case. The turbulent model is standard k-epsilon .The coordinate system is cylindrical. At flow inlet, the velocity of vapor core is different from velocity of liquid film. The boundary condition is: U = Uin,v if 0 < r < R - d U = Uin,l if R - d < r < R "d" is liquid film thickness. At flow outlet I have to enter (dk/dz) =0 and (d epsilon/dz) =0. Please help me in this regard. Your kind attention and your prompt reply would be highly appreciated. Yours Faithfully Nima Sheyad