Fluid mixing via multidirectional vortices in converging–diverging meandering microchannels with semi-elliptical side walls
Fluid mixing via multidirectional vortices in converging–diverging meandering microchannels with semi-elliptical side walls
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DOI：
10.1016/j.cej.2012.12.016
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发表时间：
2013-02
影响因子：
15.1
通讯作者：
Chih-Yang Wu;R. Tsai
中科院分区：
文献类型：
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作者：
Chih-Yang Wu;R. Tsai
本工作提出、制造并研究了一种基于具有会聚-发散横截面的曲折微通道的有效平面微混合器。微通道的侧壁由具有垂直主轴的连续半椭圆形表面组成。研究结果表明，多向涡流增强了微通道内流体的混合，包括曲流通道流中由于离心力而产生的横向迪恩涡流，以及在大流量和足够小的曲率半径情况下，由曲流通道的会聚-发散截面引起的分离涡流。我们通过单一光刻工艺制造微混合器，并使用共焦光谱显微镜成像系统观察微混合器中的流体混合。流体混合也通过商业代码进行模拟。模拟结果与实验结果基本吻合。结果表明，在大流量和小曲率半径的情况下，具有大膨胀比（定义为主通道的最大宽度除以最小宽度）的现有微混合器的混合效率总体优于具有恒定横截面的普通曲折通道微混合器。此外，更多的模拟结果表明，现有的长轴垂直的半椭圆侧壁形成的曲折通道微混合器优于长轴对齐的半椭圆侧壁形成的曲折通道微混合器、曲折-S微混合器和Sigma微混合器。
An effective planar micromixer based on a meandering microchannel with converging–diverging cross section is proposed, fabricated and investigated in this work. The side walls of the microchannel consist of successive semi-elliptical surfaces with perpendicular major axes. The results of this work show that the fluid mixing in such a microchannel is enhanced by the multidirectional vortices, including the Dean vortices in the transverse plane due to centrifugal force in the meander-channel flow and the separation vortices caused by the converging–diverging cross section of the meandering channel for the case with a large flow rate and a small enough radius of curvature. We fabricate the micromixer by a single lithography process and the fluid mixing in the micromixer is observed by using a confocal spectral microscope imaging system. The fluid mixing is also simulated by a commercial code. The simulation results are in reasonable agreement with the experimental results. The results show that the mixing efficiency of the present micromixer with a large expansion ratio defined as the maximum width divided by the minimum width of the main channel is generally better than that of the ordinary meander-channel micromixer with constant cross section for the case with a large flow rate and a small radius of curvature. Besides, more simulation results show that the present meandering-channel micromixer formed by semi-elliptical side walls with perpendicular major axes is superior to the meandering-channel micromixer formed by semi-elliptical side walls with aligned major axes, the meandering-S micromixer and the Sigma micromixer.