Equilibrium measurement method of slip length based on fluctuating hydrodynamics

TL;DR

This study uses equilibrium molecular dynamics simulations and fluctuating hydrodynamics to accurately measure slip length at nanoscale fluid-solid interfaces, linking force autocorrelation to slip behavior.

Contribution

It introduces a method combining MD simulations with fluctuating hydrodynamics to estimate slip length from force autocorrelation functions.

Findings

LFH accurately describes force autocorrelation for smooth surfaces.

Simulation data fits well with LFH predictions across multiple scales.

The method provides a reliable estimate of slip length from force fluctuations.

Abstract

We perform equilibrium molecular dynamics simulations for nanoscale fluids confined between two parallel walls and investigate how the autocorrelation function of force acting on one wall is related to the slip length. We demonstrate that for atomically smooth surfaces, the autocorrelation function is accurately described by linearized fluctuating hydrodynamics (LFH). Excellent agreement between the simulation and the LFH solution is found over a wide range of scales, specifically, from the time scale of fluid relaxation even to that of molecular motion. Fitting the simulation data yields a reasonable estimation of the slip length. We show that LFH provides a starting point for examining the relationship between the slip length and the force fluctuations.