Fluctuating hydrodynamics for dilute granular gases: a Monte Carlo study

TL;DR

This study uses DSMC simulations to analyze hydrodynamic noise in dilute granular gases, revealing that stochastic collision modeling can effectively reproduce fluctuations similar to those observed in molecular dynamics, despite differences in underlying dynamics.

Contribution

It demonstrates that stochastic collision models can accurately replicate hydrodynamic fluctuations in dilute granular gases, challenging the necessity of deterministic collision dynamics.

Findings

DSM simulations agree quantitatively with MD results on fluctuation amplitudes.

Hydrodynamic noise exhibits violation of fluctuation-dissipation relation.

Stochastic collision dynamics suffice to model hydrodynamic fluctuations.

Abstract

We investigate hydrodynamic noise in a dilute granular gas during the homogeneous cooling state, by means of a proper application of the Direct Simulation Monte Carlo (DSMC) algorithm. The DSMC includes a source of randomization which is not present in Molecular Dynamics (MD) for inelastic hard disks. Notwithstanding this difference, a fair quantitative agreement is found, including a violation of the fluctuation-dissipation relation for the noise amplitude of the same order observed in MD. This study suggests that deterministic collision dynamics is not an essential ingredient to reproduce, up to a good degree of approximation, hydrodynamic fluctuations in dilute granular gases.