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arXiv · 0805.0220

Random very loose packs

Massimo Pica Ciamarra·Antonio Coniglio
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Abstract

We measure the number Omega(phi) of mechanically stable states of volume fraction phi of a granular assembly under gravity. The granular entropy S(phi) = log Omega(phi) vanishes both at high density, at phi = phi_rcp, and a low density, at phi = phi_rvlp, where phi_rvlp is a new lower bound we call random very loose pack. phi_rlp is the volume fraction where the entropy is maximal. These findings allow for a clear explanation of compaction experiments, and provide the first first-principle definition of the random loose volume fraction. In the context of the statistical mechanics approach to static granular materials, states with phi < phi_rlp are characterized by a negative temperature.

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Massimo Pica Ciamarra, Antonio Coniglio. 2008-09-16. Random very loose packs. https://doi.org/10.1103/physrevlett.101.128001

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