A particle location based multi-level coarse-graining technique for Discrete Element Method (DEM) simulation

Large scale industrial simulations of bulk solids using the Discrete Element Method involve enormously large number of particles, therefore coarse-graining appears to be an effective technique to reduce the computational demands for such scenarios. However, most of the current coarse-graining techniques use a uniform coarse-grain ratio throughout the equipment. Such uniform coarse-graining severely limits the degree of coarse-graining possible, because at higher coarse-grain ratio, the accuracy of the simulation can be affected. To resolve this issue, a multilevel coarse-graining technique (MCG) has recently been proposed by Queteschiner et al. [Powder Technol. 338 (2018) 614] where the coarse-grain ratio varies spatially. In this work, we propose a simpler particle location based method for multi-level coarse-graining. The new method can be readily implemented using open-source software LIGGGHTS Public (DCS Computing GmbH, Linz, Austria). In this method, the coarse-grained particles disintegrate into particles of higher resolution in the refinement step at the desired spatial location and the opposite occurs during the coarsening step. The efficiency of this new coarse-graining method has been demonstrated successfully using discharge from a conical hopper as an example. Compared to uniform coarse-graining, the computational time is reduced by more than an order of magnitude without compromising on accuracy.(c) 2021 Elsevier B.V. All rights reserved.

Automated summary

Large scale industrial simulations of bulk solids often require the use of the Discrete Element Method, which can be computationally demanding due to the large number of particles involved. Coarse-graining techniques have been used to reduce the computational burden, but current methods typically employ a uniform coarse-grain ratio throughout the system. This limits the level of coarse-graining that can be achieved without sacrificing accuracy. To address this limitation, a multilevel coarse-graining technique that allows for spatial variation in the coarse-grain ratio has been proposed. In this study, a particle location based method for multi-level coarse-graining is introduced, which can be implemented using the open-source software LIGGGHTS Public. The efficiency of this method is demonstrated through successful simulations of discharge from a conical hopper, showing a significant reduction in computational time compared to uniform coarse-graining while maintaining accuracy.