Can friction replace roughness in the numerical simulation of granular materials?

Abstract

We perform numerical simulations of plane strain compression tests of Ottawa sand samples inspired by previous micro computed tomography experiments. The numerical code used for computations makes it possible to mimic in a realistic way the complex boundary conditions of the experimental test, and to introduce grains with complex morphologies based on Fourier descriptors measured on real sand grains. Since the introduction of a realistic roughness of the sand grains is very costly in terms of computation, we wish to determine if this roughness could be replaced by an artificial increase of the contact friction coefficient, without modifying the mechanical response of the sample and the localization patterns. Numerical results show that such a smoothing is actually possible to a certain extent, and guidelines are provided in order to choose with care the amount of roughness that can be compensated by friction. The resulting reduction of the computation time makes it possible to foresee future large scale simulations of realistic granular samples.