@Article{icces.2023.09833,
AUTHOR = {Jinxiang Cai, Gaojin Li},
TITLE = {Direct Numerical Simulation of Electroconvection near an Ion-Selective  Membrane Under Magnetic Field},
JOURNAL = {The International Conference on Computational \& Experimental Engineering and Sciences},
VOLUME = {25},
YEAR = {2023},
NUMBER = {1},
PAGES = {1--1},
URL = {http://www.techscience.com/icces/v25n1/53790},
ISSN = {1933-2815},
ABSTRACT = {We study the effect of magnetic field on the electro-hydrodynamics of ion transport in a liquid electrolyte 
near an ion-selective membrane using direct numerical simulation. Ion transport across the ion selective 
membrane plays an essential role in many electro-hydrodynamic and electro-microfluidic systems. Above a 
critical voltage, electroconvective instability occurs near the membrane surface, causing vortical flows in 
liquid electrolyte which enhances the mixing of cations and anions, increases the ion transport efficiency 
and causes current fluctuations. When the system is under a magnetic field, the Lorentz force generated by 
the ion movement can significantly change the flow of electrolyte solution. This effect has been used to stir
fluids in microfluidic devices or to suppress the electroconvection when combined with the electric field.
We add the Lorentz force in the coupled Poisson-Nernst-Planck-Stokes equation and study the effects of 
magnetic field on a two-dimensional electroconvection field. Simulation results show that when the 
magnetic field is applied perpendicular to the flow, the Lorentz force drives a net cross-flow similar to a 
Poiseuille flow across the two ion-selective membranes. At a high Hartman number, the electroconvection 
instability is fully suppressed when the applied voltage is slightly above the critical voltage. This effect 
essentially has the same physical mechanism as the pressure-driven channel suppressing the 
electroconvection. However, at a high Peclet number, the strong electroconvection cannot be fully 
suppressed and the cross flow is stronger than the corresponding Poiseuille flow driven by a body force 
which has the same average magnitude of the Lorentz force. Furthermore, we quantify the relative 
importance of energy dissipation due to viscous effects and magnetic effects in various transport regimes.
Our results show that the external magnetic field has the strongest effect in the space charge layer regime.},
DOI = {10.32604/icces.2023.09833}
}