Lattice Boltzmann models for non-ideal fluids with arrested phase-separation

TL;DR

This paper investigates how mid-range repulsive interactions in Lattice Boltzmann models influence non-ideal fluid phase separation, revealing that even small repulsions significantly alter droplet formation and stability, with implications for complex flow phenomena.

Contribution

It introduces a pseudo-potential energy framework to analyze stability and demonstrates the impact of mid-range repulsion on phase separation in Lattice Boltzmann models.

Findings

Mid-range repulsion creates spray-like multi-droplet configurations.

A small ten-percent increase in repulsive energy greatly enhances surface/volume ratio.

Pseudo-potential energy acts as a quasi-conserved quantity indicating stability.

Abstract

The effects of mid-range repulsion in Lattice Boltzmann models on the coalescence/breakup behaviour of single-component, non-ideal fluids are investigated. It is found that mid-range repulsive interactions allow the formation of spray-like, multi-droplet configurations, with droplet size directly related to the strength of the repulsive interaction. The simulations show that just a tiny ten-percent of mid-range repulsive pseudo-energy can boost the surface/volume ratio of the phase- separated fluid by nearly two orders of magnitude. Drawing upon a formal analogy with magnetic Ising systems, a pseudo-potential energy is defined, which is found to behave like a quasi-conserved quantity for most of the time-evolution. This offers a useful quantitative indicator of the stability of the various configurations, thus helping the task of their interpretation and classification. The present approach appears to be a promising tool for the computational modelling of complex flow phenomena, such as atomization, spray formation and micro-emulsions, break-up phenomena and possibly glassy-like systems as well.