[sincity]

dear CFD forum,
i want to modelling horizontal primary separator (gas-oil-water) using FLUENT,

here is my simulation set up:

Boundary condition : inlet (mass flow inlet)
outlet (outflow)
multiphase model : VOF implict scheme
working fluids : gas ----as primary phase
oil ----as secondary phase
water--as secondary phase
viscous model : K-epsilon standard wall function,

i did the simulation in unsteady twice but it seems no clearly interface between the phase and the contour of volume fraction seems unreal, did i make some mistakes in here??should i use UDF for this kind of simulation???