Molecular Dynamics Study of Rayleigh-Plateau Instability at Liquid-Liquid Interfaces

TL;DR

This study uses molecular dynamics simulations to analyze the Rayleigh-Plateau instability at liquid-liquid interfaces, revealing how microscopic effects and initial conditions influence the instability's growth and breakup, aligning with macroscopic theory at larger scales.

Contribution

It demonstrates that macroscopic theoretical predictions can be applicable at nanoscales under certain conditions and highlights the role of thermal fluctuations in microscopic systems.

Findings

Growth rate deviations at small radii under perturbation

Agreement with classical theory at larger radii

Thermal fluctuations significantly affect breakup dynamics at small scales

Abstract

We investigated the Rayleigh-Plateau instability at the interface between two immiscible liquids of equal viscosity using molecular dynamics simulations. Two types of initial conditions were considered, one with an imposed single-mode perturbation at the interface and the other without any imposed perturbation. Under the single-mode perturbation, the growth rate deviated from the theoretical prediction for small cylinder radii, but progressively approached and agreed with classical macroscopic theory as the radius increased. In contrast, for the unperturbed initial condition, we found a systematic relationship between the breakup time and the minimum radius, in which the power-law exponent increased with increasing radius. These results demonstrate that, even in extremely microscopic systems with cylinder radii on the order of only about fifteen atomic diameters, the growth of the instability can follow macroscopic theoretical predictions when appropriate conditions are imposed, and that the influence of thermal fluctuations on the breakup dynamics becomes increasingly significant as the system radius decreases.