In this report, we provide an update on the progress of the second part of the IFPRI Robin. In our Part 1 report, we quantitatively assessed 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 was assessed by comparing the outputs of simulations performed following the procedures of 8 industrial participants with detailed experimental data produced using Positron Emission Particle Tracking (PEPT), a technique which allows the dynamics of particulate systems to be imaged, in three dimensions, with sub-millimetre spatial resolution and sub-millisecond temporal resolution. Strikingly, of all the participants surveyed, no two institutions adopted the same practices, highlighting the need for a more standardised approach and best practice. Our results showed that while most contemporary calibration methods were able to successfully capture the dynamics of simple, free-flowing, spherical particles under low-shear conditions, and a reasonable percentage of participants could correctly predict the dynamics of angular particles, the majority 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 systems could be observed, deeper and more quantitative analysis using PEPT revealed significant disparities. 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 characterisation tests, suggesting this to be the best practice for multi-parameter DEM calibration.
In the second part of the project, we will assess the ability of DEM, and the practitioners thereof, to handle a series of still more complex particles, including binary systems whose components possess strongly differing PSDs; fine particles (both free-flowing and cohesive); and highly elongated particles. We will also explore additional industryrelevant test systems (a Resodyn acoustic mixer and a Pascall mixer), and create additional digital twins of characterisation tools used by our industrial project partners (a Granutools GranuPack, Granutools GranuFlow. aerated Freeman FT4, and Anton Paar powder rheometer). We will also use detailed sensitivity analysis to assess the suitability and efficacy of all characterisation tools explored for the determination of different DEM parameters. This brief report highlights progress made so far toward these aims, and showcases a selection of the new tools developed and data obtained. All tools and data are available, free and open source, to IFPRI members upon request.
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