Nonmonotonic reversible branch in four model granular beds subjected to vertical vibration

TL;DR

This study reveals a nonmonotonic relationship between tapping intensity and packing fraction in granular beds, showing an increase at high intensities, which challenges existing theories and is explained by arch formation properties.

Contribution

The paper demonstrates a nonmonotonic steady-state packing fraction in granular beds under tapping, supported by four models, and offers a new explanation based on arch properties.

Findings

Packing fraction increases with tapping at high intensities

Nonmonotonic behavior contradicts previous assumptions

Arch formation explains the observed phenomena

Abstract

We present results from four independent models of a granular assembly subjected to tapping. We find that the steady-state packing fraction as a function of the tapping intensity is nonmonotonic. In particular, for high tapping intensities, we observe an increase of the packing fraction with tapping strength. This finding challenges the current understanding of compaction of granular media since the steady-state packing fraction is believed to decrease monotonically with increasing tapping intensity. We propose an explanation of our results based on the properties of the arches formed by the particles.