Some important numerical aspects concerning the finite-element simulation of granular flow are presented. The main topic of this paper is the so-called "switch" phenomenon, which is a stress peak at the junction of the vertical and the inclined part of a mass flow silo during its discharge. Case studies prove that the FE simulation of silos and simplified systems should be handled with great care, as many wall pressure peaks occurring at places where the shape of the silo is changing may well be caused by numerical corner singularities. Other numerical aspects lead to consequences for the filling process and the opening phase of silo emptying.
