Self-consistent description of electrokinetic phenomena in particle-based simulations

TL;DR

This paper introduces a comprehensive computational framework for simulating electrokinetic phenomena in suspensions of charged particles, accounting for hydrodynamic and electrostatic interactions in complex geometries.

Contribution

It presents a self-consistent Langevin-based method combining Green's functions and Ewald splitting, applicable to deformable objects and arbitrary boundary conditions.

Findings

Ionic clouds are significantly affected by flow and concentration.

The method accurately captures electrokinetic motion in various conditions.

Cooperative effects emerge from particle interactions and flow dynamics.

Abstract

A new computational method is presented for study suspensions of charged soft particles undergoing fluctuating hydrodynamic and electrostatic interactions. The proposed model is appropriate for polymers, proteins and porous particles embedded in a continuum electrolyte. A self-consistent Langevin description of the particles is adopted in which hydrodynamic and electrostatic interactions are included through a Green's function formalism. An Ewald-like split is adopted in order to satisfy arbitrary boundary conditions for the Stokeslet and Poisson Green functions, thereby providing a formalism that is applicable to any geometry and that can be extended to deformable objects. The convection-diffusion equation for the continuum ions is solved simultaneously considering Nernst-Planck diffusion. The method can be applied to systems at equilibrium and far from equilibrium. Its applicability is demonstrated in the context of electrokinetic motion, where it is shown that the ionic clouds associated with individual particles can be severely altered by the flow and concentration, leading to intriguing cooperative effects.