Numerical approximations for the binary Fluid-Surfactant Phase Field Model with fluid flow: Second-order, Linear, Energy stable schemes

TL;DR

This paper introduces two linear, second-order, energy-stable numerical schemes for simulating a complex binary fluid-surfactant phase-field model coupled with fluid flow, validated through extensive 2D and 3D experiments.

Contribution

It develops novel linear, second-order, energy-stable schemes using invariant energy quadratization and projection methods for a coupled fluid-surfactant model.

Findings

Schemes are unconditionally energy stable.

Numerical experiments confirm accuracy and stability.

Methods effectively handle nonlinear coupling in the model.

Abstract

In this paper, we consider numerical approximations of a binary fluid-surfactant phase-field model coupled with the fluid flow, in which the system is highly nonlinear that couples the incompressible Navier-Stokes equations and two Cahn-Hilliard type equations. We develop two, linear and second order time marching schemes for solving this system, by combining the "Invariant Energy Quadratization" approach for the nonlinear potentials, the projection method for the Navier-Stokes equation, and a subtle implicit-explicit treatment for the stress and convective terms. We prove the well-posedness of the linear system and its unconditional energy stability rigorously. Various 2D and 3D numerical experiments are performed to validate the accuracy and energy stability of the proposed schemes.