Analytical solution of two-fluid electro-osmotic flows of viscoelastic fluids
This paper presents an analytical model that describes a two-fluid electro-osmot ic flow of stratified fluids with Newtonian or viscoelastic rheological behaviour. This is the principle of operation of an EO two-fluid pump as proposed by Brask et al. [Tech. Proc. Nanotech., 1, 190 -193, 2003], in which an electrically nonconducting fluid is transported by the interfacial dragging viscous force of a conducting fluid that is driven by electro-osmosis. The electric potential in the conducting fluid and the analytical steady flow solution of the two-fluid electro-osmotic stratified flow in a planar microchannel are presented by assuming a planar interface between the two immiscible fluids with Newtonian or iscoelastic rheological behaviour. The effects of fluid rheology, shear viscosity ratio, holdup and interfacial zeta potential are analyzed to show the viability of this technique, where an enhancement of the flow rate is observed as the shear-thinning effects are increased.