Multiple-contact discrete-element model for simulating dense granular media

Nicolas Brodu (1) , Joshua Dijksman (2, 3) , Robert Behringer (3)

1 GeoStat - Geometry and Statistics in acquisition data
2 WUR - Wageningen University and Research [Wageningen]
3 Duke Physics

This article presents a new force model for performing quantitative simulations of dense granular materials. Interactions between multiple contacts (MC) on the same grain are explicitly taken into account. Our readily applicable MC-DEM method retains all the advantages of Discrete Element Method simulations and does not require the use of costly finite element methods. The new model closely reproduces our recent experimental measurements, including contact force distributions in full 3D, at all compression levels of the packing up to the experimental maximum limit of 13%. Comparisons with classic simulations using the non-deformable spheres approach, as well as with alternative models for interactions between multiple contacts, are provided. The success of our model compared to these alternatives demonstrates that interactions between multiple contacts on each grain must be included for dense granular packings. Dense particulate media such sand, emulsions and col-loids are ubiquitous in nature and in industry. However, understanding their very rich mechanical behavior has been notoriously difficult. Numerical simulations are an essential tool to access the microscopic and macroscopic behavior of these systems. In principle, the application of solid mechanics and Newton's laws of motion to every grain in a packing should recover that packing's macro-scopic behavior. These simulations are typically referred to as Discrete Element Methods (DEM) [1] and tremendous progress has been made since the classic work of Cundall and Strack [2]. However, getting quantitative agreement between experimental results and DEM simulations is often a challenge. This is partly due to the lack of microscopic structure and force data in experiments on dense particulate media; usually only boundary stresses are available. In the last decade however, much progress has been made in obtaining microstructural data in two and three dimensional model experiments in emulsions [3, 4] and granular materials [5–7]. We have recently experimentally measured all grain-scale properties for a 3D granular system, including inter-particle contact forces, as the system was subject to controlled strain [8]. These experimental approaches provide a testing ground for DEM models. We show that conventional DEM methods need modification to give a good quantitative match to our recent 3D experimental data.

Domaines: Modélisation et simulation; Matière Molle [cond-mat.soft]; Physique Numérique [physics.comp-ph]

Nicolas Brodu, Joshua Dijksman, Robert Behringer. Multiple-contact discrete-element model for simulating dense granular media. Physical Review E , 2015, ⟨10.1103/PhysRevE.91.032201⟩. ⟨hal-01255293⟩