A combined Lattice-Boltzmann method for the simulation of two-phase flows in microchannel

• Color-field LBM and Shan & Chen LBM are combined.
• Latva-Kokko redistribution enforces a constant interface thickness.
• Shan & Chen force becomes linear and gives the interfacial tension.
• Immiscibility is guaranteed for a large span of viscosity.
• The method is validated by a droplet deformation under shear benchmark.

A new Lattice-Boltzmann method (LBM) is developed for the simulation of two-phase microflows. In this method, the phase separation is realized using Latva-Kokko redistribution scheme while the interfacial tension stress is computed according to Shan & Chen's expression. Introducing a redistribution step after the particle collision in Shan & Chen's LBM improves the algorithm stability and enforces a constant interface thickness independent of the interfacial tension. As a result, it provides independent control of the interfacial tension with little sensitivity to the viscosity. The interface curvature is easier to obtain in comparison to usual continuum surface force (CSF) and the spurious currents can be kept as low as in the color-field method. This hybrid LBM algorithm is validated by simulating a droplet deformation between two shearing plates and its capabilities demonstrated by experiments in the case of bubble generation in a T-junction microchannel using air/ethanol as the working system.