Numerical and experimental analyses of planar asymmetric split-and-recombine micromixer with dislocation sub-channels

BACKGROUND: A passive planar micromixer with dislocation sub-channels, based on the principle of planar asymmetric split and recombination, has been proposed for its effective mixing. Both numerical simulations and experiments were used to design and investigate the effect of parameters and flowing feature on mixing with Reynolds numbers ranging from 1 to 100. The mixing index, which is used as the measurement criteria, is dependent upon Reynolds number and geometrical parameters. RESULTS: Through the results of numerical and experimental simulation, it is evident that the arrangement of dislocation sub-channel structure will result in better fluid mixing owing to the combination of the unbalanced inertial collisions, the multidirectional vortices and the collision-induced flow in mixing cavities between every two-looped structure. The effect of transverse Dean Vortices in the vertical plane and expansion vortices in the horizontal plane is beneficial for the increased interfacial area between two species and promoting mixing. The increased width ratio, w₃/w₄, provided by the dislocation structures, results in better mixing performance, but also causes a higher pressure drop. Experimental results allow better validation of the mixing efficiency of this micromixer. CONCLUSION: The best mixing performance was achieved with width ratio of the dislocation sub-channels at w₃/w₄=1.0 and Reynolds numbers less than 80. To consider the mixing effect and the packaging requirements of the experiment, the mixing index of the micromixer with a dislocation sub-channel can reach 86%.