Phase separation kinetics of 2-TIPS at low density: Cluster growth by ballistic agglomeration

TL;DR

This paper investigates the phase separation kinetics in dilute active-passive particle mixtures, revealing a ballistic agglomeration mechanism that leads to faster domain growth compared to diffusive processes.

Contribution

It introduces a novel understanding of nonequilibrium growth via ballistic cluster coalescence in low-density active systems, supported by simulations and hydrodynamic modeling.

Findings

Domain growth exponent ~0.7 indicating faster coarsening

Cold particles form mobile clusters that merge ballistically

Distinct nonequilibrium growth mechanism identified

Abstract

We study the kinetics of two-temperature induced phase separation (2-TIPS) in dilute binary mixtures of active ("hot") and passive ("cold") particles using molecular dynamics simulations and a coarse-grained hydrodynamic model. Following a temperature quench, cold particles nucleate into mobile clusters that move ballistically and merge through successive coalescence events. The resulting domain growth exhibits dynamic scaling with a growth exponent of approximately 0.7, markedly faster than diffusive coarsening. We identify this regime as ballistic agglomeration of cold clusters, demonstrating a distinct nonequilibrium growth mechanism in low-density scalar active systems.