Numerical simulation of immiscible liquid-liquid flow in microchannels using lattice Boltzmann method

Immiscible kerosene-water two-phase flows in microchannels connected by a T-junction were numerically studied by a Lattice Boltzmann (LB) method based on field mediators. The two-phase flow lattice Boltzmann model was first validated and improved by several test cases of a still droplet. The five distinct flow regimes of the kerosene-water system, previously identified in the experiments from Zhao et al., were reproduced. The quantitative and qualitative agreement between the simulations and the experimental data show the effectiveness of the numerical method. The roles of the interfacial tension and contact angle on the flow patterns and shapes of droplets were discussed and highlighted according to the numerical results based on the improved two-phase LB model. This work demonstrated that the developed LBM simulator is a viable tool to study immiscible two-phase flows in microchannels, and such a tool could provide tangible guidance for the design of various microfluidic devices that involve immiscible multi-phase flows.