Fermi-like behavior of weakly vibrated granular matter

TL;DR

This paper investigates the dynamics of weakly vibrated granular matter, revealing Fermi-like statistical behavior and establishing a generalized equipartition law that links granular temperature to excitation frequency.

Contribution

It introduces a Fermi-like statistical framework and a generalized equipartition law to describe vibrated granular systems, extending beyond traditional Brownian motion models.

Findings

Granular matter exhibits Fermi-like configurational statistics.

A relation between amplitude and velocity dispersions is demonstrated.

Granular temperature correlates with external vibration frequency.

Abstract

Vertical movement of zirconia-yttria stabilized 2 mm balls is measured by a laser facility at the surface of a vibrated 3D granular matter under gravity. Realizations z(t) are measured from the top of the container by tuning the fluidized gap with a 1D measurement window in the direction of the gravity. The statistics obeys a Fermi-like configurational approach which is tested by the relation between the dispersions in amplitude and velocity. We introduce a generalized equipartition law to characterize the ensemble of particles which cannot be described in terms of a Brownian motion. The relation between global granular temperature and the external excitation frequency is established.