Phase-field Model-based Simulation of Droplet Motion on Micro-fabricated Solid Surface

Abstract

We verify the interfacial-tension effect and wetting boundary condition of a phase-field model (PFM)-based computational fluid dynamics (CFD) method and examine its applicability for simulating microscopic droplet motion on structured and heterogeneously wettable solid surfaces. Instead of the Cahn-Hilliard equation, the conservative Allen–Cahn (CAC) equation is adopted to calculate the advection and construction of diffusive interfaces. A numerical scheme based on the lattice Boltzmann model is employed to solve the Navier–Stokes equations coupled with the CAC equation for an immiscible incompressible isothermal two-phase fluid system with equal densities and viscosities. Numerical simulations in three dimensions demonstrate that the PFM-based CFD method can be used to evaluate the mobility of droplets on structured and/or partially wetted solid surfaces in various microfluidic devices and processes.