Memory effects in the relaxation of a confined granular gas

TL;DR

This paper investigates memory effects in the relaxation dynamics of a confined granular gas, comparing a kinetic model with simulations, and explores non-equilibrium phenomena like the Kovacs effect in such systems.

Contribution

It introduces a kinetic model for confined granular gases that accurately predicts temperature relaxation and captures memory effects like the Kovacs effect.

Findings

Model agrees well with molecular dynamics simulations.

Memory effects are described by a simple kinetic theory.

Possible experimental implications are discussed.

Abstract

The accuracy of a model to describe the horizontal dynamics of a confined quasi-two-dimensional system of inelastic hard spheres is discussed by comparing its predictions for the relaxation of the temperature in an homogenous system with molecular dynamics simulation results for the original system. A reasonably good agreement is found. Next, the model is used to investigate the peculiarities of the nonlinear evolution of the temperature when the parameter controlling the energy injection is instantaneously changed while the system was relaxing. This can be considered as a non-equilibrium generalization of the Kovacs effect. It is shown that, in the low density limit, the effect can be accurately described by using a simple kinetic theory based on the first Sonine approximation for the one-particle distribution function. Some possible experimental implications are indicated.