Relaxation Times in Simple Shear and the Role of Walls

Abstract

We study the relaxation time of granular media in simple shear by means of DEM simulations (the methods being Molecular Dynamics as well as Contact Dynamics) in two and three dimensions with rough and with smooth frictional walls. While the system with rough walls behaves according to its steady state constitutive laws, the systems with smooth walls show a much stronger increase of the relaxation time with driving strength than to be expected. Employing a dynamic non-local rheology model[1] allows for a stronger increase but not sufficiently so.