  Based on the continuum model for granular media developed in Dunatunga et al.
we propose a mesh-free generalized finite difference method for the simulation
of granular flows. The model is given by an elasto-viscoplastic model with a
yield criterion using the $\mu(I)$ rheology from Jop et al. The numerical
procedure is based on a mesh-free particle method with a least squares
approximation of the derivatives in the balance equations combined with the
numerical algorithm developed in Dunatunga et al. to compute the plastic
stresses.
  The method is numerically tested and verified for several numerical
experiments including granular column collapse and rigid body motion in
granular materials. For comparison a nonlinear microscopic model from Lacaze et
al. is implemented and results are compared to the those obtained from the
continuum model for granular column collapse and rigid body coupling to
granular flow.
