Diffusive mixing through velocity profile variation in microchannels

    Authors

    E. Yakhshi-Tafti; H. J. Cho;R. Kumar

    Comments

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    Abbreviated Journal Title

    Exp. Fluids

    Keywords

    PARTICLE IMAGE VELOCIMETRY; MICROMIXER; MIXER; FIELDS; SPLIT; Engineering, Mechanical; Mechanics

    Abstract

    Rapid mixing does not readily occur at low Reynolds number flows encountered in microdevices; however, it can be enhanced by passive diffusive mixing schemes. This study of micromixing of two miscible fluids is based on the principle that (1) increased velocity at the interface of co-flowing fluids results in increased diffusive mass flux across their interface, and (2) diffusion interfaces between two liquids progress transversely as the flow proceeds downstream. A passive micromixer is proposed that takes advantage of the peak velocity variation, inducing diffusive mixing. The effect of flow variation on the enhancement of diffusive mixing is investigated analytically and experimentally. Variation of the flow profile is confirmed using micro-Particle Image Velocimetry (mu PIV) and mixing is evaluated by color variations resulting from the mixing of pH indicator and basic solutions. Velocity profile variations obtained from mu PIV show a shift in peak velocities. The mixing efficiency of the I -micromixer pound is expected to be higher than that for a T-junction channel and can be as high as 80%. The mixing efficiency decreases with Reynolds number and increases with downstream length, exhibiting a power law.

    Journal Title

    Experiments in Fluids

    Volume

    50

    Issue/Number

    3

    Publication Date

    1-1-2011

    Document Type

    Article

    Language

    English

    First Page

    535

    Last Page

    545

    WOS Identifier

    WOS:000287584300003

    ISSN

    0723-4864

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