Three-dimensional simulation of mixing performance inside droplets in micro-channels by Lattice Boltzmann method

Three-dimensional multiphase/multicomponent Lattice Boltzmann model (LBM) was developed to simulate the complex hydrodynamics inside micro-droplets generated in micro-channels. Special attention was paid to the ways to generate droplets, which determined the initial liquid concentration and velocity distribution inside the droplets and accordingly made a remarkable contribution to the following mixing performance along the flow development in the micro-channels. Flow characteristics and mixing performance under different geometries and how the differences in configuration influenced the initial status of droplets were illustrated by LBM simulations. The results showed that the effective way to intensify the mixing process was to break up the bilateral symmetric fluid distribution as well as to take full advantage of the internal recirculation inside the droplet during its generation process. It is expected that general guidelines to manipulate the droplet formation and its inside mixing can be brought up through this work. Furthermore, flexible solutions can be simply provided to control the mixing process more precisely by just changing the key geometry of the microchannel.

• Developed 3D LBM models for mixing process in droplets with experimental validation. • Verified influence of micro-channel geometry on droplet generation (size and shape). • Demonstrated strong dependence of mixing in droplets on initial generation process. • Revealed sensitivity of recirculation effect to the mixing inside a micro-droplet. • Proposed potential solutions to precisely control mixing process in micro-droplets.