Experimental investigation of the freely cooling granular gas

TL;DR

This study experimentally investigates the cooling dynamics of a granular gas using diamagnetically levitated particles, confirming Haff's law at early times and modeling clustering effects at later stages.

Contribution

It provides the first experimental validation of Haff's law in a granular gas and extends the model to include clustering phenomena over time.

Findings

Good agreement with Haff's law at early times

Clustering occurs at late times

Extended Haff-like model describes the entire cooling process

Abstract

Using diamagnetically levitated particles we investigate the dynamics of the freely cooling granular gas. At early times we find good agreement with Haff's law, where the time scale for particle collisions can be determined from independent measurements. At late times, clustering of particles occurs. This can be included in a Haff-like description taking into account the decreasing number of free particles. With this a good description of the data is possible over the whole time range.