Liquid mixing behaviors inside micro-droplets in the microchannels were visualized by μ-LIF technique. These measurement results were adopted to validate the numerical simulations by a newly developed multi-phase

multi-component Lattice Boltzmann Method (LBM)

especially to determine a key parameter in the LBM model. The results showed that the simulation can successfully reveal the detailed mixing phenomena inside the droplets. It was discovered that the droplet deformation along its movement in the microchannels can significantly shorten the distance of mass transfer

and thereafter intensify the mixing process. The wetting property of the dispersed phase had strong influence on the flow pattern when the droplet passed through the complex geometry of the micro-channels. In summary

this work provided a solid foundation for the theoretical investigation of complex flows in micro-reactors.