TY - JOUR

T1 - Structural transitions in granular packs

T2 - Statistical mechanics and statistical geometry investigations

AU - Aste, T.

AU - Di Matteo, T.

PY - 2008/8

Y1 - 2008/8

N2 - We investigate equal spheres packings generated from several experiments and from a large number of different numerical simulations. The structural organization of these disordered packings is studied in terms of the network of common neighbours. This geometrical analysis reveals sharp changes in the network's clustering occurring at the packing fractions (fraction of volume occupied by the spheres respect to the total volume, ρ) corresponding to the so called Random Loose Packing limit (RLP, ρ ∼ 0.555) and Random Close Packing limit (RCP, ρ ∼ 0.645). At these packing fractions we also observe abrupt changes in the fluctuations of the portion of free volume around each sphere. We analyze such fluctuations by means of a statistical mechanics approach and we show that these anomalies are associated to sharp variations in a generalized thermodynamical variable which is the analogous for these a-thermal systems to the specific heat in thermal systems.

AB - We investigate equal spheres packings generated from several experiments and from a large number of different numerical simulations. The structural organization of these disordered packings is studied in terms of the network of common neighbours. This geometrical analysis reveals sharp changes in the network's clustering occurring at the packing fractions (fraction of volume occupied by the spheres respect to the total volume, ρ) corresponding to the so called Random Loose Packing limit (RLP, ρ ∼ 0.555) and Random Close Packing limit (RCP, ρ ∼ 0.645). At these packing fractions we also observe abrupt changes in the fluctuations of the portion of free volume around each sphere. We analyze such fluctuations by means of a statistical mechanics approach and we show that these anomalies are associated to sharp variations in a generalized thermodynamical variable which is the analogous for these a-thermal systems to the specific heat in thermal systems.

UR - http://www.scopus.com/inward/record.url?scp=53149132392&partnerID=8YFLogxK

U2 - 10.1140/epjb/e2008-00224-8

DO - 10.1140/epjb/e2008-00224-8

M3 - Article

SN - 1434-6028

VL - 64

SP - 511

EP - 517

JO - European Physical Journal B

JF - European Physical Journal B

IS - 3-4

ER -