Three phase modeling

Hi there,

I have a problem with coupling single phase and two phase flow (phase field) physics.

I would like to model ice nucleation inside a water droplet. This droplet, however, is inside a laminar air stream. I have picked two phase flow (phase-field) for the droplet and initial ice inside it, and the ice grows by time.Then the rest of the domain is considered as single phase (air). The problem is that I dont know how to couple these two physics together. In fact, I dont know how to set the boundary condition for the droplet's outer boundary (which is in contact with air) in such a way that air flow changes drop's shape.

If any body could help me I highly appreciate it.

Sean