Title: A field theory for granular packings

Author (Talk): Silke Henkes, Brandeis University

Abstract:

Based on an ensemble for static grain packings which we presented previously (PRL 99, 038002 (2007)), we develop a field theoretical model for the packings. The primary field is the Airy stress function, which is a scalar potential that incorporates force and torque balance in two dimensions. All the components of the stress tensor can be expresed in function of the Airy stress function. We propose the simplest possible field theory compatible with the symmetries of the system, and show that the structure factors for both pressure and shear are compatible with results from simulated packings. We discuss the implications for the structure of grain packings, and the link to the jamming transition.