Scaling of attraction force and rolling resistance in DEM with reduced particle stiffness

Abstract

In Discrete Element Method (DEM), the stiffness of particles is often reduced artificially for calculation speed-up. It is known that the attraction force and rolling resistance should be scaled to counter-balance the excessive energy dissipation caused by prolonged contact duration with reduced stiffness. The present study theoretically derives the scaling laws from dimensionless equations of motion in a generic form, which are for both particle translation and rotation and with multi-body interactions. It is verified that the proposed scaling laws keep the same particle motion in the dimensionless time and space during the contact of more than two particles. It is also demonstrated that the behaviour of the original (stiff) particles in Couette flow can be replicated well in various conditions in general. Some deviation to the original system could be observed in certain conditions, which is likely related to the reduction of contact frequency.