Europhys. Lett.
Volume 71, Number 1, July 2005
Page(s) 70 - 76
Section Electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics
Published online 01 June 2005
Europhys. Lett., 71 (1), pp. 70-76 (2005)
DOI: 10.1209/epl/i2004-10530-9

Response of a hexagonal granular packing under a localized external force

S. Ostojic and D. Panja

Institute for Theoretical Physics, Universiteit van Amsterdam Valckenierstraat 65, 1018 XE Amsterdam, The Netherlands

received 8 November 2004; accepted in final form 2 May 2005
published online 1 June 2005

We study the response of a two-dimensional hexagonal packing of rigid, frictionless spherical grains due to a vertically downward point force on a single grain at the top layer. We use a statistical approach, where each configuration of the contact forces is equally likely. We show that this problem is equivalent to a correlated q-model. We find that the response displays two peaks which lie precisely on the downward lattice directions emanating from the point of application of the force. With increasing depth, the magnitude of the peaks decreases, and a central peak develops. On the bottom of the pile, only the middle peak persists. The response of different system sizes exhibits self-similarity.

45.70.-n - Granular systems.
45.70.Cc - Static sandpiles; granular compaction.
46.65.+g - Random phenomena and media.

© EDP Sciences 2005