Abstract
A planar micromixer with rhombic microchannels and a converging-diverging element has been proposed for its effective mixing. Both CFD-ACE numerical simulations and experiments were used to design and investigate the effect of three parameters (number of rhombi, turning angle and absence or presence of the converging-diverging element) on mixing. Mixing efficiency is dependent upon Reynolds number and geometrical parameters. Through the results of numerical simulation, it is evident that smaller turning angle (α), higher Reynolds number and increasing number of rhombi will result in better fluid mixing due to the occurrence of larger recirculation. The large recirculation is beneficial for both the increased interfacial contact area between two species and the convective mixing. In the numerical simulations, mixing efficiency of 99% was achieved with a most efficient system consisting of three-rhombus mixer with a converging-diverging element at α = 30° and Re = 200. An experimental mixing efficiency of about 94% has been obtained with the same design parameters. As expected, it is lower than the theoretical efficiency but is still very effective. A micromixer with such design can be potentially useful in the future applications of rapid and high throughput mixing.
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Acknowledgments
This work is partially sponsored by National Science Council (NSC) under contract No NSC 94-2212-E-006-055 and 95-2221-E-006-047-MY3. We would like to extend our great thanks to the Center for Micro/Nano Science and Technology (CMNST) at National Cheng Kung University and National Nano Device Laboratories (NDL) for the access of processing and analyzing equipments. We would also like to thank National Center for High-performing Computing (NCHC) for providing the computational fluid dynamics software in this work.
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Chung, C.K., Shih, T.R. Effect of geometry on fluid mixing of the rhombic micromixers. Microfluid Nanofluid 4, 419–425 (2008). https://doi.org/10.1007/s10404-007-0197-9
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DOI: https://doi.org/10.1007/s10404-007-0197-9