Recently I've been trying to simulate a two-phase flow in Comsol. Comsol provides three methods for solving multi-phase flows.

1)two-phase (level-set)

2)two-phase (phase field)

3)two-phase moving mesh.

I need to include a viscoelastic fluid in this two-phase flow. But comsol only provide a viscoelastic flow option with single phase . So technically, level set and phase field methods aren't possible for me to use. I used viscoelastic module and then defined two deforming domains separately for viscoelastic fluid and the other Newtonian fluid. Now under viscoelastic module, i defined two fluid properties separately for two fluids and also a fluid-fluid interface. Along with all these, I also have to include electrostatics in to the system.

First of all, I would like to know whether my set-up is right or wrong. Some pictures related to my domain and set-up is attached below. While running, my interface is moving, but I'm getting inverted mesh after a while.

If someone could help me kindly reply.