Interaction between Rayleigh-Bénard and nonequilibrium electroconvective instabilities in concentration polarization: Linear stability analysis
Phys. Rev. Fluids 11, 053703 – Published 22 May, 2026
DOI: https://doi.org/10.1103/8f3q-ydtj
Abstract
This paper studies the interrelation between the Rayleigh-Bénard and the electroconvective instability in concentration polarization during ionic dc current passage from an electrolyte solution into a charge-selective solid, such as a metal electrode, an ion-exchange membrane, or a set of nanochannels. We conclude that, whereas in the underlimiting current regime the effect of electroconvection on the onset of buoyant convection is insignificant, these two phenomena become strongly intertwined at the limiting current. In this regime, the development of the extended space charge and its related nonequilibrium electroconvective instability have a major effect upon the onset of the buoyant instability; and vice versa, buoyancy has a major effect on the features of the electroconvective instability. This includes lowering of the onset threshold and regularization of the shortwave singularity typical of electroconvective instability.
