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由于固-液界面双电层的作用,平行板微通道内的压力驱动流存在动电效应。平行板微通道可简化为二维截面,其截面上双电层电场和速度场的控制方程分别采用Poisson-Boltzmann方程和修正后的Navi-er-Stokes方程。应用有限元法对控制方程进行了数值求解,计算在微通道内流体的平均流速和动电效应形成的流动电势。研究表明,微通道高度和电解质溶液浓度是影响微流体流动的主要因素。动电参数越小,动电效应对微流体的影响越大,实际值偏离经典流体理论值越大;平均流速与通道两端的压力差线性相关。
Due to the effect of the double-layer at the solid-liquid interface, there is a kinetic effect in the pressure-driven flow in the parallel plate microchannels. The parallel plate microchannels can be simplified into two-dimensional sections. The governing equations of the electric field and the velocity field of the electric double layer in the cross sections are respectively Poisson-Boltzmann equation and modified Navier-Stokes equations. The governing equations are numerically solved by finite element method, and the average flow velocity of the fluid in the microchannel and the flow potential formed by the kinetic-electric effect are calculated. The results show that the microchannel height and electrolyte solution concentration are the main factors affecting the microfluidic flow. The smaller the electrokinetic parameter is, the larger the effect of the electrokinetic effect on the microfluid is, and the larger the theoretical value deviates from the theoretical value of the classical fluid. The average flow velocity is linearly related to the pressure difference across the channel.