Vortex-assisted electroosmotic mixing of Carreau fluid in a microchannel.

Pertaining to the mixing of the non-Newtonian Carreau fluid under electrokinetic actuation inside a plane microchannel, we propose a new design of micromixer that involves inserting a two-part cylinder bearing zeta potential of the same sign but different in magnitude in the upstream and downstream directions. We numerically solve the transport equations to predict the underlying mixing characteristics. We demonstrate that a substantial momentum difference between the microchannel's plane wall and cylinder leads to the development of a vortex in the flow pathway, which in turn, enhances mixing substantially. As shown, a fluid having a highly shear-thinning nature, the vortex-assisted convection mixing strength increases with an increase in diffusivity of the candidate fluids. Also, it is shown that for the higher shear-thinning nature of the candidate fluid, an increase in cylinder radius enhances mixing efficiency and flow rate simultaneously, resulting in a "quick and efficient" mixing condition. Additionally, we established that fluid rheology significantly alters the kinetics of shear-induced binary aggregation. Our findings show that the shear-induced aggregation characteristics time sharply increases with increasing shear-thinning behaviour of the fluid. This article is protected by copyright. All rights reserved.