Abstract
I study the structural organization and correlations in very large packings of equally sized spheres, reconstructed in three dimensions with x-ray computed tomography. I show that the geometrical structure can be conveniently studied as a packing of irregular tetrahedra with volume distribution that must decay exponentially with parameters controlled by the conditions of mechanical stability, nonoverlapping, and space filling. I argue that the system’s structure can be described as constituted of two phases: (1) an “unconstrained” phase which freely shares the volume and (2) a “constrained” phase which assumes configurations accordingly with the geometrical constraints. It results that the granular system exploits heterogeneity maximizing freedom and entropy while constraining mechanical stability.
- Received 15 July 2005
DOI:https://doi.org/10.1103/PhysRevLett.96.018002
©2006 American Physical Society