Steric effects in induced-charge electro-osmosis for strong electric fields
Publication Date
8-1-2023
Document Type
Article
Publication Title
Physical Review Fluids
Volume
8
Issue
8
DOI
10.1103/PhysRevFluids.8.083702
Abstract
We study the role of steric effects on the induced-charge electro-osmosis phenomenon using a recently developed mesoscale fluid model. A hybrid Eulerian-Lagrangian method is used to simulate the dynamics of discrete immersed ions in a thermally fluctuating solvent near a metallic plate embedded in the dielectric interface. We observe that the characteristic velocity scales almost linearly with electric field when the generated ζ potentials exceed the order of the thermal voltage, as opposed to a quadratic scaling predicted by Helmholtz-Smoluchowski equation, although qualitative agreement with experiments and theories is obtained at low electric fields. Our simulations reveal that the steric effects play a crucial role at strong electric fields, which is observed from the aggregation of ions towards the center of the metal plate instead of at the edges, and the overcharging of co-ions to the surface charge near the electric double layer. A comparison to a continuum electrolyte model also highlights significant differences in charge distribution and flow field that are attributed to the steric repulsion between ions.
Funding Number
DE-AC02-05CH11231
Funding Sponsor
U.S. Department of Energy
Department
Physics and Astronomy
Recommended Citation
J. Galen Wang, Daniel R. Ladiges, Ishan Srivastava, Sean P. Carney, Andy J. Nonaka, Alejandro L. Garcia, and John B. Bell. "Steric effects in induced-charge electro-osmosis for strong electric fields" Physical Review Fluids (2023). https://doi.org/10.1103/PhysRevFluids.8.083702