Modelling of granular materials: Discrete and continuum approaches

Granular materials are abundant in nature and are, second to water, the most-handled materials on earth. These materials are found in many sectors of industry, including the pharmaceutical, food, agriculture, construction and mining sectors. Activities include transportation, storage, mixing and blending, screening, crushing and milling. Bulk solid handling is one of the largest industrial activities in the world, consuming 10% of all the energy produced. It is estimated that 40% of the capacity of industrial plants is wasted due to a lack of understanding of granular material behaviour. Even though granular materials are so important, our understanding of their behaviour is still limited.

Our aim is to model granular materials and to predict their bulk behaviour so that the design of handling and processing equipment can be improved. For this, two numerical approaches are available, namely discrete- and continuum-based models. Discrete-based models, such as the discrete element method, can easily model the discrete nature and large deformation of the material, including complex processes such as mixing. However, careful calibration of these models is necessary, and computations can be time-consuming. Continuum-based models, such as the finite element method, on the other hand, find it more difficult to model large deformation, and therefore advanced mesh-less approaches are needed. One such approach is the material point method. This lecture discusses the two approaches and the advantages and disadvantages of each, and demonstrates how they can be applied to model industrial applications.

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Short biography

Corné Coetzee is a professor in the Department of Mechanical and Mechatronic Engineering. He grew up on a commercial fruit farm, which also served as a base for the family earth-moving construction company. From an early age, he was exposed to heavy machinery and the ‘moving of soil’. Hence, when a final-year research project on this topic became available, he discovered his passion for research and a wider interest in the behaviour of granular materials in general. His research focuses on the modelling of granular materials (bulk solids) using various numerical techniques and predicting their behaviour for the design of improved handling and processing equipment. He has established a laboratory for observing and measuring granular material behaviour and the calibration and validation of numerical models. The equipment is used for research purposes and is also providing a service to industry. Aligned with his interest in agriculture, he is also involved in the modelling and design of paperboard packaging for the horticultural sector, closely working together with the Faculty of AgriSciences. He is registered as a professional engineer with the Engineering Council of South Africa and is an NRF B-rated researcher.

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