EH-DPD: a Dissipative Particle Dynamics approach to Electro-Hydrodynamics

TL;DR

This paper introduces a mesoscale Dissipative Particle Dynamics method for electro-hydrodynamics that incorporates ion dynamics and thermal fluctuations, validated through electroosmotic flow simulations.

Contribution

It develops a novel DPD-based framework for electro-hydrodynamics that links free-energy, fluctuation-dissipation, and ionic fluxes, enabling more accurate nanofluidic modeling.

Findings

The model accurately simulates electroosmotic flows with ion size effects.

Using Van der Waals equation captures ionic finite size effects.

Significant differences observed in concentration and velocity profiles.

Abstract

Electrohydrodynamics is crucial in many nanofluidic and biotechnological applications. In such small scales, the complexity due to the coupling of fluid dynamics with the dynamics of ions is increased by the relevance of thermal fluctuations. Here, we present a mesoscale method based on the Dissipative Particle Dynamics (DPD) model of the fluid. Two scalar quantities, corresponding to the number of positive and negative ions carried by each DPD particle, are added to the standard DPD formulation. We introduced a general framework that, given the definition of the free-energy of the DPD particle, allows to derive a fluctuation-dissipation relation and the expression for ionic fluxes between the DPD particles. This provides a link between the dynamics of the system and its equilibrium properties. The model is then validated simulating a planar electroosmotic flow for the cases of overlapping and non overlapping electric double layers. It is shown that using a Van der Waals equation of state the effect of ionic finite size can be accounted, leading to significant effects on the concentration and velocity profiles with respect to the ideal solution case.