Mobility-dependent bifurcations in capillarity-driven two-phase fluid systems by using a lattice Boltzmann phase-field model

Abstract

Bifurcations in capillarity-driven two-phase fluid systems, due to different mobilities in phase-field models for such systems, are studied by using a lattice Boltzmann method (LBM). Specifically, two-dimensional (2D) and three-dimensional (3D) droplets on a flat wall with given wettability variations are investigated. It is found that the mobility controls the rate of diffusive relaxation of the phase field from non-equilibrium toward equilibrium, and similar to previous findings on mechanically driven two-phase systems, the mobility is closely related to the contact line velocity. For the cases investigated, different mobilities across a critical value result in fundamentally different system evolution routes and final stable equilibrium states. These results may provide some implications for phase-field study of droplet manipulations by surface wettability adjustments in microfluidics. Copyright © 2008 John Wiley & Sons, Ltd.