Nucleation and Growth of Droplets in Vapor-Liquid Transitions

TL;DR

This paper investigates vapor-liquid transition kinetics through molecular dynamics simulations, revealing different growth mechanisms at critical and sub-critical densities, including hydrodynamic growth and droplet nucleation.

Contribution

It provides detailed simulation evidence distinguishing between hydrodynamic and nucleation growth mechanisms in vapor-liquid transitions.

Findings

At critical density, bicontinuous domain growth follows hydrodynamic predictions.

Below critical density, phase separation occurs via nucleation and droplet growth.

Early-time growth is faster, possibly due to inter-droplet interactions.

Abstract

Results for the kinetics of vapor-liquid transitions, following temperature quenches with different densities, are presented from the molecular dynamics simulations of a Lennard-Jones system. For critical density, bicontinuous liquid and vapor domains are observed which grow with time obeying the prediction of hydrodynamic mechanism. On the other hand, for quenches with density significantly below the critical one, phase separation progresses via nucleation and growth of liquid droplets. In the latter case, Brownian diffusion and collision mechanism for the droplet growth is confirmed. We also discuss the possibility of inter-droplet interaction leading to a different amplitude in the growth law. Arguments for faster growth, observed at early time, are also provided.