# Large Mpemba-like effect in a gas of inelastic rough hard spheres

## TL;DR

This paper demonstrates a giant Mpemba effect in a gas of inelastic rough spheres, where hotter samples can cool faster than colder ones, explained by coupled rotational and translational temperature dynamics.

## Contribution

It reveals a large Mpemba effect in a gas of inelastic rough spheres and explains it using a simple Maxwellian approximation for velocity distribution.

## Key findings

- The effect occurs even with temperature differences over an order of magnitude.
- Theoretical predictions match molecular dynamics and Monte Carlo simulations.
- Rotational and translational temperatures are key to the effect.

## Abstract

We report the emergence of a giant Mpemba effect in the uniformly heated gas of inelastic rough hard spheres: The initially hotter sample may cool sooner than the colder one, even when the initial temperatures differ by more than one order of magnitude. In order to understand this behavior, it suffices to consider the simplest Maxwellian approximation for the velocity distribution in a kinetic approach. The largeness of the effect stems from the fact that the rotational and translational temperatures, which obey two coupled evolution equations, are comparable. Our theoretical predictions agree very well with molecular dynamics and direct simulation Monte Carlo data.