Phase-field model-based simulation of two-phase fluid motion on partially wetted and textured solid surface

Our objective in this study is to examine the applicability of a numerical method [1, 2] to simulation of motions of microscopic two-phase uid on solid surfaces for evaluating uidic devices and for predicting underground uid ows. The method adopts a conservation-modi ed Allen-Cahn equation of phaseeld model (PFM) [3,4] for advection and formation of interfaces and lattice-Boltzmann method (LBM) [3] as numerical solution scheme. In PFM, an interface is autonomously reproduced as a nite uid region between phases without imposing topological constraints as phase boundary. Wettability of solid surface can be taken into account through a simple boundary condition. In semi-Lagrangian LBM, the simple particle-kinematic operation in discrete conservation form on an isotropic spatial lattice is useful for high-performance computing. The method therefore has an attractive advantage over the others, e cient simulation of complex two-phase uid motions on partially-wetted and textured surfaces. The major ndings in preliminary immiscible liquid-liquid simulations are as follows: (1) the method simulated well departure of droplet from solid surface due to buoyancy in agreement with semi-empirical prediction; (2) the droplet took larger static contact angles on textured hydrophobic surfaces than on the at ones in a similar way with those in experiments.