Title: Defining and measuring a granular continuum element

Author (Talk): Christopher Rycroft, Department of Mathematics, MIT

Abstract:

For some states of matter, it is possible to derive continuum laws by starting with a description of an idealized microscopic element of the material. One of the key obstacles in deriving continuum laws for dense granular materials has been the absence of a well-defined \\\"granular element\\\" due to the particle discreteness: how can a continuum stress tensor be defined, when the local interactions between particles are inhomogeneous, and extended force chains exist? In this work, I will present a variety of non-homogeneous Discrete Element Method simulations, and show that material quantities (such as stress, strain rate, and free volume) can be successfully interpreted at a mesoscopic scale. This information can be used to locally test some of the key hypotheses that are commonly used in modeling granular materials, providing insight into how to formulate a better continuum theory.