Electro-osmotic Effects in Low Reynolds Number Flow through a Planar Microfluidic Contraction-expansion

Spurred by the growing interest in utilising electroosmotic flow for microfluidic applications, a finite volume computational fluid dynamics (CFD) method is used to investigate steady electro-osmotic flows through a planar microfluidic contraction-expansion at low Reynolds number. The axial concentration profiles and pressure and potential changes occurring over the flow domain are compared with the results of two variants of a network theory that assumes that the flow within each distinct channel segment is fully developed. It is found that a model based on the matching of ‘ion currents’ (currents associated with the fluxes of individual ion species) exhibits better agreement with the CFD simulations than the alternative concentration-matching approach previously described in the electrokinetics literature.