The Two-Phase Thin-Film Flow, Domain, Phase Field interface () found under the Multiphase Flow>Two-Phase Thin-Film Flow, Phase Field branch (), is a multiphysics interface designed to track the interface between two immiscible fluids. The fluids are assumed to flow in a narrow channel that is represented by a domain within the geometry.

When adding the Two-Phase Thin-Film Flow, Domain, Phase Field multiphysics interface, a Thin-Film Flow, Domain and a Phase Field interfaces are added to the Model Builder. In addition, a multiphysics coupling feature, The Two-Phase Thin-Film Flow, Field Coupling Feature, is added automatically under the Multiphysics node.

Simulations using the Two-Phase Thin-Film Flow, Domain, Phase Field interface are always time-dependent since the position of an interface is almost always dependent of its history.

By default the fluid flow discretization is set to P1+P1, and the phase field discretization is set to Linear. This combination provides an improved conservation of the integral of the phase field variable when using the nonconservative form of the phase field thin-film flow equations.