  We present a simple and efficient method to simulate three-dimensional,
complex-shaped, interacting bodies. The particle shape is represented by
Minkowski operators. A time-continuous interaction between these bodies is
derived using simple concepts of computational geometry. The model (particles +
interactions) is efficient, accurate and easy to implement, and it complies
with the conservation laws of physics. 3D simulations of hopper flow shows that
the non-convexity of the particles strongly effects the jamming on granular
flow.
