analysis of mixing efficiency in an electroosmotically micromixer with heterogeneous wall charge distribution

in this paper, numerical investigation of a flat passive micromixer with heterogeneous surface properties that the flow through it, is driven by the electroosmotic flow have been presented. the governing equations, which consist of a laplace equation for the distribution of external electric potential, a poisson equation for the distribution of electric double layer potential, modified navier-stokes equations for the flow field, the nernst-planck equation for the distribution of ions concentration have been solved numerically for an incompressible steady flow of a newtonian fluid using the finite-volume method. the key features of an ideal electro-osmotic flow with uniform zeta potential has been compared with analytical solutions for the ionic concentration and velocity fields for the validation of the numerical scheme. results show that the arrangement of the heterogeneous surface properties has a significant impact on the efficiency of mixing. maximum mixing efficiency is related to the condition that the asymmetry in the wall of the heterogeneous arrangement loads increase. the increase in intensity of the electric charge with constant power load of the electroosmotic micropump enhances the efficiency of mixing.