Webinars

Abstract - The modelling and simulation of granular materials at the Centre for Bulk Solids and Particulate Technologies (CBSPT) at the University of Newcastle, Australia goes back to the mid-90s. The period since has seen advancements from continuum mechanics-based analysis to application of Finite Element Method (FEA), Discrete Element Method (DEM) and Computational Fluid Dynamics (CFD) in assessment, design, technology development and commercialization. The areas of research and industry application vary widely in scale and outcomes depending on the ores and minerals, grains and powders handled. Applications include belt and pneumatic conveying, transfers, dust emissions, fluidization, biomass rheology, heat transfer, maritime cargo stability, moisture migration and dewatering, build-up and cohesion/adhesion, wear, particle degradation and vibrated screening.

In the recent past and at present, advancing technology and computational readiness has seen coupling between these different modelling approaches while calibration and validation methods have expanded in scope to include large physical scale models, carefully considered design of experiments and automation. This presentation will share some of the interesting applications in materials handling using different software, models and approaches that have been undertaken, including translation of expertise to engineering design and simulation standards adopted by industry. Presented are current activities and projects such as coarse particle separation in vibrated fluidized beds using CFD-DEM and moisture migration under oscillatory motions coupling DEM and smoothed particle hydrodynamics (SPH). 

Biography - Dr Dusan Ilic is a fellow, chartered engineer and research academic at the University of Newcastle, located at the Newcastle Institute for Energy and Resources with 20 years’ experience of consultancy and applied research. Since starting in his current role in 2017, he has used a foundation of bulk solids handling and particle science to establish and grow multi-disciplinary research programmes in engineering and beyond. His project portfolio includes ARC Discovery biomass pneumatic conveying, Industrial Transformation Hub advancing Australian iron ore technologies, Centre of Excellence for enabling eco-efficient beneficiation of minerals, MRFF's EPCDR initiative on bushfire smoke and direct engagement with industry and government.

Abstract - The concept of random close packed or maximally random jammed configurations in particles is well established: Granular particles, particularly frictionless spheres, do not manage to attain the crystalline close packed configurations but ‘get stuck’ in this amorphous state. This effect is due to a geometric frustration that the locally densest configuration cannot expand into the globally densest crystalline configuration. 

In this talk, we will look at a broader range of packing or tessellation models and discuss amorphous states similar to what the random close packed is for the packing problem. We will look at tessellations and packing problems defined by optimization with respect to certain properties, such as interface area in the Kelvin problem, packing density in the Kepler problem, or cell centrality as in the Quantizer problem. 

In all known cases, the optimal solutions are crystalline configurations with long range order. Amorphous disordered structures are generally considered to be intermittent metastable states that prevent the system from attaining the optimal ordered structures. To date, no optimization problem has been identified where the groundstate  is a disordered configuration. While we do not find a disordered groundstate, we here show that the use Lloyd’s algorithm as a fast quench generates a very stable universal disordered state in the three-dimensional Quantizer problem, despite the existence of lower-energy crystalline configurations.

We will discuss these states in terms of the degree of density uniformity of the packings and ask the question whether these pertinent disordered states can be used as a signature of the model that defines the tessellation. 

Biography - Prof Gerd Schröder-Turk hold a PhD degree from the Australian National University, for his thesis “Skeletons in the Labyrinth”. 

He has held academic appointments in theoretical physics and applied maths departments at the Australian National University, the Friedrich-Alexander University Erlangen-Nuremberg and Murdoch University. 

He is a Fellow of the American Physical Society and the recipient of the 2014 Emmy-Noether-Prize, the 2019 Camurus Lipid Research Foundation Fellowship award and the 2023 Allan Schoen Award. He is currently a Professor at Murdoch University and an Honorary Associate Professor at the Australian National University. Aside from his teaching and research roles, he takes a keen interest in higher education policy and university governance, and has held roles as Senate member of Murdoch University and in the National Executive of the Australian Institute of Physics. 

Abstract: Suspensions of fine and cohesive particles demonstrate pressure dependent rate and extent during solid-liquid separation. This is usually termed ‘compressible’ behaviour. Such suspensions are common across minerals processing, water treatment, and food processing, to name but a few. Unfortunately, traditional theories of sedimentation and filtration assume incompressible behaviour. In contrast, compressional rheology, developed in 1987, is a theoretical framework for compressible suspensions that explicitly incorporates pressure dependent effects. Since 1987, researchers at The University of Melbourne have developed a suite of sedimentation, centrifugation and filtration techniques for extracting locally varying compressibility and permeability. These properties are used in process models of thickeners, filters, and centrifuges, for example, to predict performance and provide insights into process optimisation.

Biography: A/Prof Anthony Stickland is an academic in Chemical Engineering at The University of Melbourne, where he lectures ‘Fluid Mechanics’, ‘Particle Technology’, and ‘Sustainable Minerals and Recycling’.  He is a Chief Investigator in the ARC Centre of Excellence for Enabling Eco-Efficient Mineral Beneficiation and leads the Sludge Group, which undertakes research in particulate suspension rheology and solid-liquid separation. This research covers (1) material characterisation techniques and analysis tools to be able to adequately describe particle and suspension behaviour, (2) models of processes to be able to predict performance for design and optimisation, and (3) development and commercialisation of novel technologies for suspension dewatering and handling. The Sludge Group works closely with industries such as water treatment and minerals processing.

Recording of the seminar here.