Modeling Induced-Charge Electroosmosis using a meso-scale approach

We apply a recently developed method for simulating electrolytes at the mesoscale, the Discrete Ion Stochastic Continuum Overdamped Solvent (DISCOS) algorithm, to study the complex electrokinetic effect Induced Charge Electro-Osmosis (ICEO). Electrokinetic flows are important in many applications such as microfluidic pumping and desalination, and in understanding a range of biological processes. ICEO is specifically interesting because an applied field can be used generate bulk flows in an electroneutral system. One crucial aspect of ICEO is the development of electric double layers. Thermal fluctuations play a crucial role in this process, which cannot be captured at this scale by a purely continuum model. While molecular dynamics can faithfully model the double layer, high computational cost makes it challenging to apply this approach to real applications. To overcome these challenges we employ DISCOS, where the solvent is modeled using continuum fluctuating hydrodynamics, and ions are treated discretely using the immersed boundary method. We compare our results to experiments and theories using simulations with a ζ-potential below and on the order of the thermal voltage, and explore applied electric fields outside of this parameter space.