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

• Published in: International journal for numerical methods in fluids 2009-05, Vol.60 (2), p.203-225
• Main Authors: Huang, J. J., Shu, C., Chew, Y. T.
• Format: Article
• Language: English
• Subjects: Applied fluid mechanics; bifurcation; Computational methods in fluid dynamics; Condensed matter: structure, mechanical and thermal properties; contact line; droplet; Exact sciences and technology; Fluid dynamics; Fluidics; Fundamental areas of phenomenology (including applications); lattice Boltzmann method; mobility; Physics; Solid-fluid interfaces; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Wetting
• ISSN: 0271-2091; 1097-0363
• DOI: 10.1002/fld.1885

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.