Abstract
In particulate soft matter systems the average number of contacts of a particle is an important predictor of the mechanical properties of the system. Using x-ray tomography, we analyze packings of frictional, oblate ellipsoids of various aspect ratios , prepared at different global volume fractions . We find that is a monotonically increasing function of for all . We demonstrate that this functional dependence can be explained by a local analysis where each particle is described by its local volume fraction computed from a Voronoi tessellation. can be expressed as an integral over all values of : . The local contact number function describes the relevant physics in term of locally defined variables only, including possible higher order terms . The conditional probability to find a specific value of given a global packing fraction is found to be independent of and . Our results demonstrate that for frictional particles a local approach is not only a theoretical requirement but also feasible.
- Received 7 July 2014
DOI:https://doi.org/10.1103/PhysRevLett.114.158001
© 2015 American Physical Society