FINITE-DIFFERENCE SOLUTION OF ELECTROKINETIC FLOW THROUGH MICROCHANNEL

Abstract

Electroviscous effects near solid-liquid interface in steady, fully developed, non-Newtonian, pressure-driven flow of power-law liquids through a uniform rectangular microchannel have been investigated numerically by solving the Poisson—Boltzmann and the momentum equations using a finite difference method. An electric body force term is caused by the electric double field and flow-induced electrokinetic field is considered in equation of motion. The microchannel wall is considered to have uniform surface charge density and the liquid is assumed to be a symmetric 1:1 electrolyte solution. Electroviscous resistance will reduce the velocity that is adjacent to the wall, relative to the velocity on the axis. This effect was greater when the liquid is shear-thinning, and less when it is shear-thickening, than it is for Newtonian flow. The electro-viscous effect is stronger in shear-thinning, and weaker in shear-thickening liquids, than it is when the liquid is Newtonian. But mainly Newtonian fluids are solved first.