How to model Navier Stokes equations on two phases

Hello everyone,

I’m attempting to model the Navier Stokes equations for a fluid that falls due to gravity and the force of an electric field (a phenomenon similar to electrospinning), however I don’t know how to model the moving interphase for the Navier Stokes on fenics. Is there any reference I could check in order to get a grasp into how the equations are solved with a changing interphase.