直微通道中的电黏性效应

摘要

This paper aims to investigate the power-law fluid flow in microchannel with eletrokinetic effects.In the entire analysis,the electric double layer (EDL) potential is described by the Poisson equation.The flow and transport of the power-law fluid is characterized by the Navier-Stokes equation and the Nernst-Plank equation.Numerical simulation is carried out for all values of the flow behavior index from 0.4 to 1.2.The effects of the flow behavior index,ionic concentration and channel dimension on fluid velocity distribution,streaming potential and apparent viscosity are discussed.The results show that the eletroviscous effect on the flow depends significantly on the flow behavior index.For the shear thinning fluid of the flow behavior index n＜ 1,the fluid viscosity and velocity increase with the value of n increase.For the shear thickening fluid of n＞ 1,the influence of the flow behavior index on the velocity and streaming potential can be neglected in practical application.%为了研究直微通道中幂律流体的电黏性效应,建立了压力驱动微通道内流体流动的数学模型,其中双电层电势分布、流体流动及流动粒子输运特性分别由Poisson-Boltzmann(P-B)方程、Navier-Stokes(N-S)方程及Nernst-Plank(N-P)方程描述.讨论了微通道中有电黏性效应时溶液浓度;幂律指数对微通道内流体的速度分布、流动电场强度的影响.结果表明:对于n＜1的剪切变稀流体,流体的黏度和流动速度随着n的增大而减小,变化非常明显;而对于n＞1的剪切变稠流体,黏度和流动速度几乎不受n的影响,在实际应用中可以忽略不计.