Cooling dynamics of a dilute gas of inelastic rods: a many particle simulation

TL;DR

This paper uses simulations to study the cooling behavior and cluster dynamics of a dilute inelastic gas, revealing how fluctuations prevent collapse and how energy dissipation affects long-term energy decay.

Contribution

It introduces a stochastic collision model for inelastic particles that suppresses collapse, enabling long-term simulation of large systems in the inelastic regime.

Findings

Fluctuations in energy transfer prevent inelastic collapse.

Large clusters form and reach local equilibrium within but not between clusters.

Energy decay follows a t^{-2} scaling law at long times.

Abstract

We present results of simulations for a dilute gas of inelastically colliding particles. Collisions are modelled as a stochastic process, which on average decreases the translational energy (cooling), but allows for fluctuations in the transfer of energy to internal vibrations. We show that these fluctuations are strong enough to suppress inelastic collapse. This allows us to study large systems for long times in the truely inelastic regime. During the cooling stage we observe complex cluster dynamics, as large clusters of particles form, collide and merge or dissolve. Typical clusters are found to survive long enough to establish local equilibrium within a cluster, but not among different clusters. We extend the model to include net dissipation of energy by damping of the internal vibrations. Inelatic collapse is avoided also in this case but in contrast to the conservative system the translational energy decays according to the mean field scaling law, E(t)\propto t^{-2}, for asymptotically long times.