Investigation of efficient mixing enhancement in planar micromixers with short mixing length

Achieving rapid mixing of different liquids in a short distance is important for biochemical applications. Here, a new type of micromixers consisting of double symmetrical V-shaped baffles (MMA and MMB mixers) and double asymmetrical V-shaped baffles (MMC and MMD mixers) is proposed. Numerical simulations are performed to evaluate their mixing performance when the Reynolds number (Re) ranges from 0.1 to 50. Meanwhile, the visualization of vortex formation is conducted to analyze the mixing mechanism. The results show that the mixing efficiency of all mixers approaches 0.8 for all Re at the short distance of 3500 mu m. At relatively low Re=0.5, the MMA and MMB perform better than MMC and MMD due to more adequate molecular diffusion; whereas the unbalanced lateral flows and multidirectional vortices in the MMC and MMD induce stronger chaotic convection at high Re=50, leading to a higher performance. Moreover, the disturbance created by the vortex on the mass transfer surface is not only relying on its vorticity but also correlates with the position of vortex/vortex leg. Lastly, all micromixers are fabricated, tested and compared with the simulation results and both of them show a good agreement.

Automated summary

Achieving rapid mixing of different liquids in a short distance is crucial for biochemical applications. A new type of micromixers consisting of double symmetrical V-shaped baffles and double asymmetrical V-shaped baffles is proposed, which can achieve high mixing efficiency. The performance of the micromixers varies at different Reynolds numbers, with better performance of the symmetrical baffles at low Reynolds numbers and better performance of the asymmetrical baffles at high Reynolds numbers.