Direct numerical simulation of electrohydrodynamic flow instabilities in microchannels

Abstract

Fluids with gradients in electrical conductivity subjected to strong electric fields can undergo violent instability. In flows where molecular diffusion is slow, high conductivity gradients can be maintained beyond the initial instability and become a driver for chaotic flow. Despite the low Reynolds number in microchannel applications, molecular diffusion occurs slow enough that such flows are possible. This work investigates a class of electrically driven, conductivity gradient flow instabilities in microchannels that display turbulent characteristics at low Reynolds number. Flows far from the influence of solid boundaries and flows confined between parallel plates are considered. Electroosmotic flow at solid boundaries is also considered and found to have a dramatic impact on the flow. A variety of configurations and assumptions are studied using direct numerical simulation. © 2005 Elsevier B.V. All rights reserved.