Induced charge electroosmotic flow with finite ion size and solvation effects.

Abstract

The most common mathematical models for electrolyte flows are based on the dilute solution assumption, leading to a coupled system of the Nernst--Planck--Poisson drift-diffusion equations for ion transport and the Stokes resp. Navier--Stokes equations for fluid flow of the solvent. In charged boundary layers the dilute solution assumption is in general not valid and volume exclusion and solvation effects have to be taken into account in a thermodynamically consistent way. Whenever boundary layer effects have a dominant impact on the global behavior of a certain electrochemical system, an accurate numerical simulation depends on the correct incorporation of these effects. In this contribution we present a novel numerical solution approach which aims at preserving on the discrete level consistency with basic thermodynamic principles and structural properties like independence of flow velocities from gradient contributions to external forces. We illustrate capabilities of the method by an example of vortex generation due to induced charge electroosmotic forces at an electrode inside a nanochannel.