# Frictional Cooling of Granular Gases: A Molecular Dynamics Study

## TL;DR

This study uses large-scale molecular dynamics simulations to analyze how frictional granular gases cool and evolve over time, revealing clustering, velocity ordering, and power-law growth of velocity correlation length.

## Contribution

It provides new insights into the late-time behavior of frictional granular gases, including velocity ordering and clustering, through detailed simulation analysis.

## Key findings

- Velocity field follows Maxwell-Boltzmann distribution initially
- Clustering appears at later times in density field
- Velocity correlation length grows as t^{1/3}

## Abstract

We study the free evolution of frictional granular gases using large scale molecular dynamics simulation in three dimensions. The system cools due to solid friction among the interacting particles. At early stages of evolution, the density field remains homogeneous and the velocity field follows the Maxwell-Boltzmann (MB) distribution. However, at later times, the density field shows clustering and the velocity field shows local ordering. The ordering in the velocity field is studied by invoking analogy from phase ordering systems. The equal-time correlation function of velocity field follows dynamical scaling. The correlation length of velocity field, $L_v(t)$, exhibits power law growth: $L_v(t)\sim t^{1/3}$.