Growth regimes in three-dimensional phase separation of liquid-vapor systems

TL;DR

This study uses large-scale 3D lattice Boltzmann simulations to identify kinetic and inertial growth regimes in liquid-vapor phase separation, challenging previous viscous regime assumptions.

Contribution

It provides the first evidence of distinct kinetic and inertial regimes with specific growth exponents in 3D liquid-vapor phase separation, ruling out the viscous regime.

Findings

Kinetic regime with growth exponent 1/2 identified

Inertial regime with growth exponent 2/3 identified

No evidence of viscous regime with exponent 1 in 3D liquid-vapor separation

Abstract

The liquid-vapor phase separation is investigated via lattice Boltzmann simulations in three dimensions. After expressing length and time scales in reduced physical units, we combined data from several large simulations (on $512^3$ nodes), with different values of viscosity, surface tension and temperature, to obtain a single curve of rescaled length $\hat{l}$ as a function of rescaled time $\hat{t}$. We find evidence of the existence of kinetic and inertial regimes with growth exponents $\alpha_d=1/2$ and $\alpha_i=2/3$ over several time decades, with a crossover from $\alpha_d$ to $\alpha_i$ at $\hat{t} \simeq 1$. This allows us to rule out the existence of a viscous regime with $\alpha_v=1$ in three-dimensional liquid-vapor isothermal phase separation, differently from what happens in binary fluid mixtures. An in-depth analysis of the kinetics of the phase separation process, as well as a characterization of the morphology and the flow properties, are further presented in order to provide clues into the dynamics of the phase-separation process.