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Generation and Control of Electrohydrodynamic Flows in Aqueous Electrolyte Solutions
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On the Dynamical Regimes of Pattern-Accelerated Electroconvection
Scott M Davidson1, Matthias Wessling2,3, Ali Mani1
1Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA.
Scientific Reports
|March 4, 2016
Summary
Electroconvection enhances ion transport across membranes. Patterning surfaces can surprisingly boost ion transport rates by up to 80%, revealing new electrokinetic behaviors.
Area of Science:
- Electrochemistry
- Fluid Dynamics
- Surface Science
Background:
- Electroconvection enhances ion transport at polarized surfaces, overcoming diffusion limitations.
- Surface topology and electrochemical inhomogeneities influence overlimiting transport onset.
- Mechanisms by which surface variations promote transport are not well understood.
Purpose of the Study:
- To analyze electroconvective flows generated by patterned impermeable stripes on membranes.
- To investigate the potential of surface patterning to regularize electrokinetic instabilities.
- To understand how surface variations influence ion transport mechanisms.
Main Methods:
- High-resolution direct numerical simulations were employed.
- Analysis focused on geometric patterns of impermeable stripes on ion exchange membranes.
- Simulations explored both patterned and nonpatterned membrane scenarios.
Main Results:
- Reducing the permeable area of ion exchange membranes via patterning increased ion transport rates by up to 80%.
- A novel regime of electroconvection was identified in nonpatterned membranes.
- This novel regime allows for multivalued current due to the coexistence of multiple convective states.
Conclusions:
- Surface patterning of ion exchange membranes is a viable strategy to significantly enhance ion transport.
- Electroconvection exhibits complex behaviors, including multivalued current regimes, under specific conditions.
- Further research into surface-induced electroconvection can optimize ion transport in electrochemical systems.
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