Numerical Investigation of Electroosmotic Mixing in Microchannels with Heterogeneous Zeta Potential

The present study reports numerical analysis of micromixing for mixed electroosmotic/pressure driven flow of Newtonian fluid in microchannels. Two dimensional Laplace, Poisson-Boltzmann, momentum, and species concentration equations are solved numerically using finite volume method and SIMPLE algorithm. The equations are solved for rectangular microchannels with heterogeneous zeta potential distribution along the channel walls. Flow streamlines are presented for microchannels with and without electroosmotic effect. The simulation results indicate an enhancement in species mixing by introducing the heterogeneous electroosmotic effect. In addition, effects of zeta potential, bulk electrolyte concentration, external applied electric field, Reynolds number, and channel height are investigated on characteristics of species mixing. Results show that species mixing is improved by increasing the zeta potential, bulk electrolyte concentration, external applied electric field, and the channel height; whilst mixing efficiency is decreased by increasing Reynolds number.