On entropic characterization of granular materials

Raphael BlumenfeldEarth Science & Engineering, Imperial College, London SW7 2AZ, UKandCavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE, UK1.1 AbstractThis chapter presents recent developments in entropic characterization ofgranular materials. The advantages of the formalism and its use are illus-trated for calculation of structural characteristics, such as porosity uctu-ations and the throat size distribution. I discuss the relations between theentropic formalism and stress transmission. It is argued that a new sub-ensemble of loading distributions is necessary, which introduces a tensortemperature-like quantity named angoricity.1.2 Introduction: the entropic formalismThe introduction of statistical mechanical methods to analyse assemblies ofgranular systems has led to the development of new concepts in the eld.Most notable are the concepts of compactivity, the analogue of temper-ature, and of a volume function, the analogue of the Hamiltonian. Theapproach is based on a description of the entropy of the granular structure,namely, the statistics of con gurations that a collection of grains can as-sume, given that they are con ned to a container of a given volume V. Thisapproach, developed originally by Edwards and collaborators [1], has been