Chaoticity of the Wet Granular Gas

TL;DR

This paper derives an analytic expression for the Kolmogorov-Sinai entropy of dilute wet granular matter, revealing that humidity significantly increases the chaotic behavior of the granular gas.

Contribution

It provides the first analytic formula for the entropy of wet granular matter, accounting for the effects of humidity on chaos in any spatial dimension.

Findings

Kolmogorov-Sinai entropy increases rapidly with liquid addition

Humidity significantly enhances the chaoticity of wet granular gases

Analytic expression valid for any spatial dimension

Abstract

In this work we derive an analytic expression for the Kolmogorov-Sinai entropy of dilute wet granular matter, valid for any spatial dimension. The grains are modelled as hard spheres and the influence of the wetting liquid is described according to the Capillary Model, in which dissipation is due to the hysteretic cohesion force of capillary bridges. The Kolmogorov-Sinai entropy is expanded in a series with respect to density. We find a rapid increase of the leading term when liquid is added. This demonstrates the sensitivity of the granular dynamics to humidity, and shows that the liquid significantly increases the chaoticity of the granular gas.