Strong breakdown of equipartition in uniform granular mixtures

TL;DR

This paper investigates the energy distribution in a binary inelastic granular mixture, revealing conditions where energy equipartition breaks down and identifying two distinct state classes.

Contribution

It introduces a detailed analysis of temperature differences and asymptotic velocity ratios, highlighting the strong breakdown of equipartition in certain regimes.

Findings

Identification of parameter regions with temperature disparities

Asymptotic analysis of velocity ratios in the large-mass limit

Discovery of 'normal' and 'ordered' states with distinct energy distributions

Abstract

A binary mixture made of heavy and light inelastic hard spheres in the free cooling state is considered. First, the regions in the parameter space where the partial granular temperature of the heavy species is larger (or smaller) than that of the light species are analyzed. Next, the asymptotic behavior of the mean square velocity ratio in the disparate-mass limit is investigated, assuming different scaling laws for the parameters of the mixture. It is seen that two general classes of states are possible: a "normal" state and an "ordered" state, the latter representing a strong breakdown of energy equipartition.