Simulation of a two-dimensional shear cell

Molecular dynamics (MD) simulations of a two-dimensional (2D) shear cell of Couette type are presented. The simulation is adjusted to corresponding experimental studies and the results are compared with the experimental results of model granulate consisting of about 3000 photoelastic disks. A shear zone next to the rotating inner wall is observed. The distribution of tangential velocity of the disks shows an exponential decrease within the shear zone and the angular velocities of the disks oscillate in the shear zone. The probability distributions of the fluctuational tangential, radial, and angular velocities of the disks become narrower with increasing distance from the inner boundary and are non-Gaussian with exponential flanks. We find a comparatively weak influence of both, the restitution coefficient, and the friction coefficient, on the tangential velocity profile, whereas the packing fraction crucially determines the system's response. The contact network of the disk packing reveals force chains. The mean fabric tensor for each disk shows a different behavior within and outside the shear zone. The probability distribution of normal contact forces shows an exponential decay for high forces. [S1063-651X(99)12301-8].