Lees-Edwards boundary conditions for the multi-sphere discrete element method

A consistent implementation of Lees-Edwards boundary conditions is proposed for the Multi-Sphere Discrete Element Method, which can mitigate various unphysical effects at the bulk and micro-structural levels. These effects include non-linear velocity profiles and inhomogeneous particle distributions, which result in significant errors with respect to pressure and granular temperature. In order to allow for a fair assessment of different implementations, a novel compound sphere particle shape is devised for comparison to reliable benchmark data generated from systems of spherical particles. The Multi-Sphere Discrete Element Method is utilised to examine two implementations of these conditions. The commonly used Naive approach results in the aforementioned unphysical effects, which are numerical artefacts causing deviations from the benchmark results of up to one order of magnitude. Meanwhile, the proposed consistent implementation fulfils the fundamental requirements of Lees-Edwards boundary conditions and produces data which are in excellent agreement with the benchmark results, as well as the available literature. Comparing the aforementioned implementations, general principles are developed for implementing Lees-Edwards boundary conditions for the Multi-Sphere Discrete Element Method.& nbsp; & nbsp;(c) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study proposes a consistent implementation of Lees-Edwards boundary conditions for the Multi-Sphere Discrete Element Method to mitigate unphysical effects and errors. By comparing with reliable benchmark data and pointing out numerical artefacts of the Naive approach, the proposed consistent implementation is shown to produce data in excellent agreement with benchmark results and literature.