Abstract

In this report, we quantitatively assess the effectiveness of discrete element method (DEM) calibration methods utilised by 8 industrial DEM practitioners for a number of differing experimental geometries, particulate media, and combinations thereof. The accuracy of the methods is assessed by comparing the outputs of simulations performed following the procedures of the 8 participants with detailed experimental data produced using Positron Emission Particle Tracking (PEPT), a technique which allows the dy- namics of particulate systems to be imaged, in three dimensions, with sub-millimetre spatial resolution and sub-millisecond temporal resolution. Strikingly, of all the par- ticipants surveyed, no two institutions adopted the same practices, highlighting the need for a more standardised approach and best practice. Our results show that while most contemporary calibration methods are able to successfully capture the dynamics of simple, free-flowing, spherical particles under low-shear conditions, the vast major- ity of procedures tested were unable to correctly reproduce the behaviours of smaller, more cohesive particles, or higher-shear environments. For the latter case, though qualitative agreement and visual similarity between simulated and experimental sys- tems could be observed, deeper and more quantitative analysis using PEPT revealed significant disparities. A number of methodologies were able to successfully capture the dynamics of aspherical, highly-angular particles, but no advantage was observed in the implementation of complex and computationally-intensive geometric models over the simpler and more efficient rolling-friction method for the materials and systems explored. Of the calibration methods examined, the most effective – indeed the only one to consistently reproduce the experimentally-measured dynamics of the cohesive systems tested – involved the combination of both static and dynamic powder char- acterisation tests, suggesting this to be the best practice for multi-parameter DEM calibration.