# Intruders in disguise: Mimicry effect in granular gases

## TL;DR

This paper investigates the mimicry effect in granular gases, identifying conditions where different components share the same translational and rotational temperatures, supported by kinetic theory and simulation validation.

## Contribution

It introduces a theoretical framework to determine when multicomponent granular gases exhibit energy equipartition, specifically the mimicry effect, based on particle properties.

## Key findings

- Conditions for mimicry depend on specific mass ratios and size ratios.
- Theoretical predictions align well with DSMC and molecular dynamics simulations.
- Smaller spheres must have higher particle mass density than larger spheres.

## Abstract

In general, the total kinetic energy in a multicomponent granular gas of inelastic and rough hard spheres is unequally partitioned among the different degrees of freedom. On the other hand, partial energy equipartition can be reached, in principle, under appropriate combinations of the mechanical parameters of the system. Assuming common values of the coefficients of restitution, we use kinetic-theory tools to determine the conditions under which the components of a granular mixture in the homogeneous cooling state have the same translational and rotational temperatures as those of a one-component granular gas (``mimicry'' effect). Given the values of the concentrations and the size ratios, the mimicry effect requires the mass ratios to take specific values, the smaller spheres having a larger particle mass density than the bigger spheres. The theoretical predictions for the case of an impurity immersed in a host granular gas are compared against both DSMC and molecular dynamics simulations with a good agreement.