Challenges in modelling diffusiophoretic transport

TL;DR

This paper examines the challenges in modeling diffusiophoretic transport, comparing different simulation methods within a unified thermodynamic framework, and highlights the impact of finite Peclet-number effects on these methods.

Contribution

It introduces a unified framework for diffusio-osmosis and compares boundary-driven and field-driven NEMD methods, revealing differences in finite Peclet-number effects.

Findings

Boundary-driven and field-driven methods should be equivalent at weak gradients.

Finite Peclet-number effects are more pronounced in boundary-driven flows.

Fictitious color forces reduce Peclet-number effects in simulations.

Abstract

The methodology to simulate transport phenomena in bulk systems is well-established. In contrast, there is no clear consensus about the choice of techniques to model cross-transport phenomena and phoretic transport, mainly because some of the hydrodynamic descriptions are incomplete from a thermodynamic point of view. In the present paper, we use a unified framework to describe diffusio-osmosis(phoresis), and we report non-equilibrium Molecular Dynamics (NEMD) on such systems. We explore different simulation methods to highlight some of the technical problems that arise in the calculations. For diffusiophoresis, we use two NEMD methods: boundary-driven and field-driven. Although the two methods should be equivalent in the limit of very weak gradients, we find that finite Peclet-number effects are much stronger in boundary-driven flows than in the case where we apply fictitious color forces.