Shear Flow of an Electrically Charged Fluid by Ion Concentration Polarization: Scaling Laws for Electroconvective Vortices
Name
Kwak-2013-Shear Flow of an Electrically Charged Fluid by Ion.pdf
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Author(s)
Kwak, Rhokyun
Pham, Van Sang
Lim, Kian Meng
Han, Jongyoon
Date Issued
March 2013
Journal
Physical Review Letters
Publisher
American Physical Society
Citation
Kwak, Rhokyun, Van Sang Pham, Kian Meng Lim, and Jongyoon Han. Shear Flow of an Electrically Charged Fluid by Ion Concentration Polarization: Scaling Laws for Electroconvective Vortices. Physical Review Letters 110, no. 11 (March 2013). © 2013 American Physical Society
Version
Final published version
Abstract
We consider electroconvective fluid flows initiated by ion concentration polarization (ICP) under pressure-driven shear flow, a scenario often found in many electrochemical devices and systems. Combining scaling analysis, experiment, and numerical modeling, we reveal unique behaviors of ICP under shear flow: a unidirectional vortex structure, its height selection, and vortex advection. Determined by both the external pressure gradient and the electric body force, the dimensionless height of the sheared electroconvective vortex is shown to scale as (ϕ[superscript 2]/U[subscript HP])[superscript 1/3], which is a clear departure from the previous diffusion-drift model prediction. To the best of our knowledge, this is the first microscopic characterization of ion concentration polarization under shear flow, and it firmly establishes electroconvection as the mechanism for an overlimiting current in realistic, large-area ion exchange membrane systems such as electrodialysis. The new scaling law has significant implications on the optimization of electrodialysis and other electrochemical systems.
MIT Department
Massachusetts Institute of Technology. Department of Biological Engineering
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
Massachusetts Institute of Technology. Department of Mechanical Engineering
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DOI of Published Version
https://doi.org/10.1103/PhysRevLett.110.114501
