二维微槽道电渗流的增强混合

微尺度流动中的混合一直是微流系统研制中的一个大问题,对壁面zeta势非均匀分布情况下的二维微槽道电渗流进行了数值分析,重点分析了这种情况下的微流动混合增强.基于电渗流的Helmholtz-Smoluchowski滑移速度模型,应用SIMPLE方法计算了4种滑移速度在整个壁面上的分布不均匀一致时的微槽道电渗流动的流场及被动标量在其中的混合.计算结果表明,滑移速度的非均匀一致导致微槽道电渗流中的流线发生剧烈的转折,从而使得微槽道流动的混合效率有很大的提高.流场中流线的转折越剧烈、转折的次数越多,微槽道流动混合效率的提高就越大.

Enhanced mixing in 2D micro-channel electro-osmotic flows

Micro electro-mechanical system (MEMS) elements are extremely small,so slow mixing due to low Reynolds number is the one of most significant performance limitations for micro-fluidic systems.The present work is a numerical study of the electro-osmotic flows (EOF) in micro-channel with non-uniform wall zeta potential. In particular, the mixing enhancements of micro-channel flow were investigated, which are due to induced transverse flows resulting from the variations in the wall zeta potential. Based on the Helmholtz-Smoluchowski wall slip velocity model for EOF, four cases of electro-osmotic flows in micro-channel with non-uniform wall slip velocitys and the mixing of the passive scale in these flows were computed with the semi-implicit method for pressure-linked equations (SIMPLE) algorithm. The results show that the non-uniform wall slip velocitys induce zigzag streamlines, and as a result, the mixing are enhanced. In generally, the mixing efficiency increases with the strength of the transverse flows.