Viscosity, granular‐temperature, and stress calculations for shearing assemblies of inelastic, frictional disks

Abstract

Employing nonequilibrium molecular‐dynamics methods the effects of two energy loss mechanisms on viscosity, stress, and granular‐temperature in assemblies of nearly rigid, inelastic frictional disks undergoing steady‐state shearing are calculated. Energy introduced into the system through forced shearing is dissipated by inelastic normal forces or through frictional sliding during collisions resulting in a natural steady‐state kinetic energy density (granular‐temperature) that depends on the density and shear rate of the assembly and on the friction and inelasticity properties of the disks. The calculations show that both the mean deviatoric particle velocity and the effective viscosity of a system of particles with fixed friction and restitution coefficients increase almost linearly with strain rate. Particles with a velocity‐dependent coefficient of restitution show a less rapid increase in both deviatoric velocity and viscosity as strain rate increases. Particles with highly dissipative interactions re...