Effect of wall bumpiness on the behavior of sheared dry bidisperse granular material

In order to investigate the interface behavior of bidisperse granular material under plane shearing conditions, a series of DEM simulations were performed by keeping the shear velocity and the confining pressure constant. The granular mixture is composed of two sizes particles having a size ratio of 2, with a volume proportion of small spheres Ps equal to 38.5%. The effect of wall bumpiness on interface granular material behavior revealed that monodisperse and bidisperse systems behave similarly, the small spheres in the vicinity of the bumpy surface governing the system behavior. For a given wall bumpiness, the effect of Ps on the effective friction coefficient and granular material behavior is then studied. The results reveal that there is a critical Ps, in our case about 20%, above which the effective friction coefficient remains unchanged, the velocity profile being linear and the system being governed by small particles in the vicinity of bumpy walls. However, for lower Ps (<20%), sliding occurs and the interface behavior of the system is governed by big particles.