| Andrew McBride and Thomas Shire |
| Mon 05 Jun 2017, 13:00 - 14:00 |
| AGB Seminar Room AGB Building, King’s Buildings, EH9 3JL |
If you have a question about this talk, please contact: Martina Manes (s1688520)
ANDREW McBRIDE
Abstract:
The motivation for the work is to develop a better understanding of the physics that describes granular systems in rotating drums. This is the first step to understanding more complex and industrially important processes such as tumbling mills that are an integral component of the comminution process.
In this presentation, the constitutive laws of dense granular flow in a rotating drum are investigated. Discrete Element Method simulations of the drum at varying speeds are performed. From the resulting data, kinematic and kinetic measures are extracted and used to investigate the validity of the assumptions made for constitutive relations that have been proposed in the literature: that is, (a) the isotropic response of the material and (b) the incompressibility of the material.
The rotating drum system is found to be largely isotropic for high rotational speeds. For low rotational speeds, anisotropy is observed in the bottom part of the system, where the particles are flowing upwards. A small degree of compressibility is observed in the downward-flowing layer.
The friction coefficient for the granular material is also investigated. A new empirically-derived friction law is found to have a better fit to the data when compared to other friction laws proposed in the literature.
An overview of the experimental facilities present at the University of Cape Town to investigate dynamic granular systems will also be given.
Bio-note:
Andrew graduated with a MSc (Civil Engineering) from the University of Cape Town (UCT) in 2000. He spent a brief time working as a Civil Engineer, before embarking on a research career in the Centre for Minerals Research at UCT. The focus of his work was on the simulation of granular systems with application to the minerals processing industry. During this period, he embarked on a PhD with Prof. Daya Reddy on various aspects of the theory and computation of non-classical plasticity. After graduating in 2008, he spent two years as a research officer in the Centre for Research in Computational and Applied Mechanics (CERECAM, UCT) working on problems in plasticity, biomechanics, granular flow and homogenization. In 2010, he moved to the Chair of Applied Mechanics at the University of Erlangen– Nuremberg to pursue his postdoctoral studies with Prof. Paul Steinmann. The focus of the research was on non-classical models of diffusion, surface elasticity theory and computational homogenization. In mid 2012 he returned to CERECAM as a Senior Researcher. Throughout his career he has been interested in the use of quality, open-source tools for scientific computation. Since the beginning of 2016, Andrew has been a Senior Lecturer at the University of Glasgow in the Division of Infrastructure and Environment. He is also an Honorary Researcher at the University of Cape Town.
THOMAS SHIRE
Abstract:
The retention capability of granular filters is controlled by the narrow constrictions connecting the voids between filter particles. The theoretical justification for filter rules used in geotechnical practice are empirical and based on filter particle size, rather than being informed by experimental or numerical observations of the constriction size distribution (CSD).
This presentation reports the results of direct, particle-scale measurement of the CSD within virtual samples of granular filters created using the discrete element method (DEM). The resultant data are used to explore quantitatively the influence of the coefficient of uniformity, particle size distribution and relative density of the filter on the CSD. The effectiveness of the analytical method using inscribed circles to estimate constriction sizes is also explored.
Bio-note:
Tom Shire joined the University of Glasgow as a Lecturer in Geotechnical Engineering in April 2017. From August 2016 to March 2017 he was a Research Associate in the Geotechnics section at Imperial College London, focusing on laboratory testing of unsaturated soils and from January 2015 to August 2016 he was a Teaching Fellow in Civil Engineering, also at Imperial.
Tom graduated from the University of Nottingham in 2005 with an MEng in Civil Engineering with German. Following this he spent four years working for Scott Wilson Ltd. (now part of Aecom) as an assistant geotechnical engineer. In 2009 he joined Imperial College to study for an MSc in Soil Mechanics, followed by a PhD focusing on discrete element modelling (DEM) of granular filters for embankment dams. After submission of his PhD thesis, Tom spent just over one year as a geotechnical engineer at Atkins Ltd.