Electro-osmotic flow of viscoelastic fluids in microchannels under asymmetric zeta potentials

Abstract

The flow of viscoelastic fluids between parallel plates under the combined influence of electro-osmotic and pressure gradient forcings with asymmetric boundary conditions, by considering different zeta potentials at the walls, is investigated. The fluids are z-z symmetric electrolytes. The analytic solutions of the electrical potential, velocity distributions and streaming potential are based on the Debye-Huckel approximation for weak potential. The viscoelastic fluids used are modelled by the simplified Phan-Thien-Tanner constitutive equation, with linear kernel for the stress coefficient function, and the Finitely Extensible Nonlinear Elastic dumbbells model with a Peterlin approximation for the average spring force. The combined effects of fluid rheology, electrical double-layer thickness, ratio of the wall zeta potentials and ratio between the applied streamwise gradients of electrostatic potential and pressure on the fluid velocity and stress distributions are discussed.