Numerical and experimental analyses of planar micromixer with gaps and baffles based on field synergy principle

The characteristics of fluid flow and mass transfer in a novel micromixer with gaps and baffles are studied numerically and experimentally. Based on the principles of multiple vortices, abrupt contraction/expansion and twice split/recombine, the effects of gaps and baffles are investigated considering both mixing performance and pressure drop at Reynolds numbers ranging from 0.1 to 60. The mixing efficiency of the novel micromixer is found to be as high as over 94% at extremely low (Re = 0.1) or high Reynolds number (Re ≥ 40). The mechanism of mass transfer enhancement in the novel micromixer is analyzed by the field synergy principle. It is found that the novel micromixer is helpful to mass transfer enhancement which can be attributed to a good synergy between the velocity field and the concentration field. It is shown that the field synergy principle provides an alternative way to evaluate the performance of micromixers. In addition, the influence of the different locations of gaps and baffles on the mixing performance is analyzed. The comprehensive performance of micromixers is investigated by the field synergy principle and the ratio of the mixing index to the pressure drop (MI/PD). The merits of rapid mixing, low energy consumption and short mixing length make the novel micromixer more promising in microfluidic application.