Multicomponent flow

Hello,everyone

I am using the SC multicomponent model to simulate the flow process of oil drops in water. The oil drops are in the center of the channel. When I apply the velocity and pressure boundary to the water, and the oil drops do not add the pressure and velocity boundary, the simulation will diverge. Do I need to add the boundary to the oil drops, or other methods? I would appreciate it if you could help me with this problem.

Thanks