Issue
EPL
Volume 79, Number 2, July 2007
Article Number 24002
Number of page(s) 6
Section Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics, and Fluid Dynamics
DOI http://dx.doi.org/10.1209/0295-5075/79/24002
Published online 03 July 2007
EPL, 79 (2007) 24002
DOI: 10.1209/0295-5075/79/24002

Effects of self-organization on transport in granular matter: A network-based approach

A. Smart1, P. Umbanhowar2 and J. Ottino1

1  Department of Chemical and Biological Engineering, Northwestern University Evanston - Evanston, IL 60208, USA
2  Department of Physics and Astronomy, Northwestern University Evanston - Evanston, IL 60208, USA


received 26 February 2007; accepted in final form 6 June 2007; published July 2007
published online 3 July 2007

Abstract
Granular matter may be one of the simplest prototypes of what have come to be regarded as complex systems -systems where simple interactions can lead to rich, often surprising, global behavior. For example, interparticle contacts in a granular system give rise to networks that are 1) heterogeneous, i.e., a few particles support high compressive force, while many others support relatively little, and 2) self-organized, i.e., spatially correlated strong forces tend to form a sub-network of interconnecting "force chains". Using numerical simulations, we investigate the influence of heterogeneity and self-organization on the transport properties of granular matter, with particular attention to heat conduction -a phenomenon of ubiquitous importance in engineering and nature. We find that self-organization in the granular network promotes efficient transport. Furthermore, a network-attack experiment suggests that contacts with high betweenness centrality, not necessarily those with highest local heat transfer coefficient, most significantly influence transport behavior. We find that concepts of network theory yield valuable insight -both qualitative and quantitative- into the observed behavior.

PACS
45.70.-n - Granular systems.
05.60.-k - Transport processes.
05.65.+b - Self-organized systems.

© Europhysics Letters Association 2007