Mixing enhancement by utilizing electrokinetic ins

Authors: Zheyan Jin Hui Hu

Publish Date: 2010/04/18

Volume: 13, Issue: 3, Pages: 229-239

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Abstract

An experimental study was conducted to assess the effectiveness of manipulating convective electrokinetic instability EKI waves to control/enhance fluid mixing inside three Yshaped microchannels which includes a conventional straight channel a channel with microcavities and a channel with microsteps Epifluoresence imaging technique was used to conduct qualitative flow visualization and quantitative scalar concentration field measurements inside the microchannels The effects of the applied static and alternating electric fields on the evolution of the convective EKI waves and the resultant fluid mixing process were quantified in terms of scalar concentration distributions shedding frequency of the EKI waves fluid mixing efficiency and mixing augmentation factor While the fluid mixing efficiency was found to increase monotonically with the increasing strength of the applied static electric fields for all the studied microchannels the channel with microcavities was found to have the best overall mixing enhancement performance among the three studied microchannels It was found that fluid mixing processes in the microchannels would be further enhanced by adding alternating electric perturbations to the applied static electric fields regardless the frequency and magnitude of the alternating electric perturbations The fluid mixing process would be most enhanced when the frequency of the alternating electric perturbations is close to the “natural frequency” of the EKI waves ie the shedding frequency of the EKI waves with the applied static electric fields onlyThe support of National Science Foundation CAREER program under award number of CTS0545918 is gratefully acknowledged The authors would also like to thank Prof Ryszard Jankowiak and Dr Abdulilah Dawoud for their help in making the Yshaped microchannels used in the present study

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