Electro-hydrodynamics of binary electrolytes driven by modulated surface potentials

TL;DR

This paper develops a theoretical framework for understanding the electro-hydrodynamics of binary electrolytes near insulating surfaces under modulated AC voltages, revealing new high-frequency behaviors beyond circuit model predictions.

Contribution

It introduces an analytical approach combining perturbation theory and numerics to describe non-equilibrium electrolyte dynamics under modulated potentials, extending existing circuit models.

Findings

Analytic solutions for pressure, velocity, and electric potential fields.

Good agreement between numerical simulations and linear theory.

Discovery of high-frequency dynamics not captured by circuit models.

Abstract

We study the electro-hydrodynamics of the Debye screening layer that arises in an aqueous binary solution near a planar insulating wall when applying a spatially modulated AC-voltage. Combining this with first order perturbation theory we establish the governing equations for the full non-equilibrium problem and obtain analytic solutions in the bulk for the pressure and velocity fields of the electrolyte and for the electric potential. We find good agreement between the numerics of the full problem and the analytics of the linear theory. Our work provides the theoretical foundations of circuit models discussed in the literature. The non-equilibrium approach also reveals unexpected high-frequency dynamics not predicted by circuit models.