Abstract
In this study, a numerical simulation method for microscopic liquid-liquid two-phase flow was proposed that adopted a lattice-Boltzmann method (LBM) as solution scheme for fluid-dynamic equations and also a phase-field model (PFM) for fluid interface formation and interfacial-tension forcing. Instead of Cahn-Hilliard-type advection equation in conventional PFM-based methods for two-phase flows, a conservation-improved Allen-Cahn-type equation was used for lower-cost calculation of diffuse-interface advection. The method was applied to mono-dispersed slug droplets flow problem in T-junction microchannel with square cross section. The volumetric flow rate ratio was set within low Reynolds, capillary and Weber numbers for a silicone oil-water system with hydraulic diameter of 100 nm, interfacial tension of 41.6 mN/m and kinematic viscosity of 1.0 cSt. The major findings were as follows: (1) The continuous and dispersed-phase droplets became shorter at nearly-constant length difference between them as their flow rates were increased; (2) The slug lengths agreed with experimental data.
