Micromorphic modeling of granular dynamics

This paper provides micromorphic modeling of a granular material. Micromorphic modeling treats an individual particle as a microelement and the particle composition in a representative volume element as a macroelement. By specifying the volume of a macroelement, continuum volume-type quantities such as mass density, body force, body couple, kinetic energy density, internal energy density, specific heat supply, etc., are determined by taking the averages of their discrete counterparts in a macroelement. The discrete expressions for the divergence of surface-type quantities (fluxes) are obtained with the help of discrete–continuum analogy for the discrete balance equations. We demonstrate that the discrete formulation of stress tensor in the dynamic condition, which involves both contributions from body forces and relative particle accelerations in a macroelement, can be simply expressed in terms of contact forces and branch vectors. This study constructs complete discrete-type and continuum-type balance equations for a granular material in a macroelement and at a macroscopic point, using the discrete–continuum correspondence for these field quantities.