Grain Days 2025

The properties of granular and porous materials are closely tied to the structure of the overall assembly and the shape of the constituent particles. Therefore an ability to characterise structure, shape and topoloy in a physically meaningful way is paramount for such materials. The statistical nature of the systems and the complexity of the shapes however make this a challenging task. This lecture will explore some geometric methods for this task, based on Set Voronoi diagrams, on pore space characterisation methods and on Minkowski tensor methods.

About the speaker:

Prof Gerd Schroeder-Turk holds a PhD degree from the Australian National University, for his thesis “Skeletons in the Labyrinth”. He has held academic appointments in physics and 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, of the 2019 Camurus Lipid Research Foundation Fellowship award and the 2024 Alan Schoen Award. He is currently a Professor at Murdoch University, an Honorary Associate Professor at the ANU, an elected member of the Academic Council Murdoch University. From 2018 to 2024, he was the staff-elected member of Murdoch University’s Senate, and he has held roles as member of the Australian Institute of Physics National Executive and as the chairman of the Congress of the Australian Institute of Physics in 2018. He takes a keen interest in all aspects of higher education strategies and university governance, has been a public commentator on higher education and was named amongst the Times Higher Education ‘People of the Year’ that mattered in higher education in 2019.

This Lecture will introduce the field of “grainsize dynamics” – the mechanics dealing with the evolution of particle size distributions in space and time, and their governing forces. Typical forces in grainsize dynamics include mixing, segregation, crushing, agglomeration, grain growth and reduction. The Lecture will focus on the first three forces. After introducing the stochastic particle scale physics that control each of these mixing, segregation and crushing dynamics, the Lecture will next show how the effects of these stochastic mechanisms could be theoretically upscaled to frame enriched continuum models. A discussion will follow on why “open-system” dynamics by mixing and segregation do not lend themselves for hierarchical approach that artificially identifies scales and treat them separately. Although the physics of grain crushing can be understood using a “closed-system” idealisation, when coupled with mixing and segregation, the modelling of grain crushing also requires an open-system description within a heterarchical approach that does not separate scales (yet benefits from non-hierarchical organisational rules). Finally, grainsize dynamics will be coupled with the surrounding pore network that when coupled with local momenta, paves the way to a fully new Heterarchical Granular Dynamics (HGD) computational paradigm. 

About the speaker:

Immediately after his PhD at the Technion in 2002, Itai joined the University of Western Australia as a postdoctoral researcher in offshore geomechanics. In 2005, he joined the University of Sydney as a Senior Lecturer and was promoted to Full Professor in 2012. At Sydney, he also serves as the Director of the Sydney Centre in Geomechanics and Mining Materials (SciGEM). His research is intentionally broad, guided by a passion for bridging physics and engineering. This interdisciplinary focus has enabled him to make significant contributions across both domains while developing a versatile toolkit of theoretical, computational, and experimental methods. Building on this foundation, Itai has advanced research in areas such as geomechanics, granular physics, geophysics, solid and fluid mechanics, and minerals processing, as well as in interdisciplinary collaborations at the interface with the arts. Itai has been the founding President of ANAGRAM and is currently the Chair of TC105 – Geomechanics from micro to macro. 

Continuum constitutive models are the backbone of numerical simulations and predictions in geomechanics. By definition, these models assume smooth behaviour, an assumption carried from early courses in Mechanics of Materials through to advanced elasto-plastic and critical state soil mechanics frameworks. However, real geomaterials often fail through localisation, shear bands, and cracking, processes that ultimately break the assumption of continuity. In addition, grains within an RVE are constrained to respond in a homogenised way, reporting only the averaged stress and strain. While effective in many contexts, this restriction can obscure critical mechanisms at meso and micro scales and lead to misinterpretations in both theory and application. Are we missing something important and what are the consequences in practical applications? What can be done? This lecture will examine the underlying mechanisms of deformation and failure in granular materials across scales, and their implications for continuum modelling. Particular focus will be on the challenges classical constitutive models face in capturing discontinuities and evolving internal structures. Different approaches to enrich continuum formulations with lower scale information will be discussed, with an emphasis on how these developments can improve the prediction of failure at larger scales. The lecture aims to bridge the gap between grain-scale physics and continuum frameworks, and to highlight future directions for constitutive modelling of geomaterials.

About the speaker:

A/Prof Giang D Nguyen obtained his DPhil in Engineering Science (majoring in Computational Mechanics) from the University of Oxford in 2005. His doctoral research focussed on constitutive modelling based on nonlocal theory, its thermodynamic formulation and Finite Element (FEM) applications to modelling failure of concrete at the structural scale. He spent 1.5 years as a postdoctoral researcher at the University of New Mexico (UNM) in Albuquerque working on large-scale simulations of sea ice failure (hundreds of kilometres) using the Material Point Method (MPM). This was followed by six years at the University of Sydney, first as a postdoc and later as a lecturer, where he advanced Breakage Mechanics for grain-scale effects in continuum models and extended his earlier work on bridging meso and macro scales in modelling localised failure. Over the past 12 years at the University of Adelaide, his research has centred on bridging behaviour and failure processes across multiple scales in engineering materials, including geomaterials, metals, and composites, through an integrated combination of theoretical, experimental, and numerical approaches. He has secured numerous competitive grants from the Australian Research Council, including multiple Discovery Projects and a prestigious Future Fellowship. Since 2015, he has served as an Editor of Materials and Design and currently sits on the Editorial Boards of Computer and Geotechnics and the International Journal of Rock Mechanics and Mining Sciences.