  We present simulations of static model sandpiles in two dimensions (2D) and
focus on the stress distribution in such arrays made of discrete particles. We
use the simplest possible model, i.e. spherical particles with a linear spring
and a linear dashpot active on contact and without any frictional forces. Our
model is able to reproduce several recent theoretical predictions. For
different boundary conditions we examine the contact network and the stresses
in the array and at the bottom of the pile. In some cases we observe a dip,
i.e. the relative minimum in pressure, under the center of the pile. We connect
the dip to arching, and we relate arching to the structure of the contact
network. Finally, we find that small polydispersity is sufficient to cause a so
called stress-network, i.e. strong fluctuations in stress. From those data we
determine the probability distribution for the vertical stress at the bottom
and relate it to theoretical and other numerical work.
