Resolving the microscopic hydrodynamics at the moving contact line

TL;DR

This paper combines advanced molecular dynamics simulations with continuum models to resolve the microscopic hydrodynamics at moving contact lines, clarifying dissipation mechanisms at different interfaces.

Contribution

It introduces novel averaging techniques that align MD simulations with continuum FEM models at molecular scales, enhancing understanding of contact line dissipation.

Findings

MD simulations match FEM continuum descriptions at molecular scales

Dissipation at the liquid-solid interface is characterized by Navier-slip

Contact line dissipation is negligible on smooth substrates

Abstract

The molecular structure of moving contact lines (MCLs) and the emergence of a corresponding macroscopic dissipation have made the MCL a paradigm of fluid dynamics. Through novel averaging techniques that remove capillary waves smearing we achieve an unprecedented resolution in molecular dynamics (MD) simulations and find that they match with the continuum description obtained by finite element method (FEM) down to molecular scales. This allows us to distinguish dissipation at the liquid-solid interface (Navier-slip) and at the contact line, the latter being negligible for the rather smooth substrate considered.