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Benjy Marks

Benjy Marks photo

BE (Hons), BSc
Postgraduate Research Student




Particles and Grains Laboratory,
School of Civil Engineering,
Email:
Web: zerp.ly/benjymarks

Research project - Size segregation in crushable polydisperse shear flows

Supervisor: A/Prof Itai Einav

We are trying to model the relatively poorly understood phenomenon of particle size segregation in granular flows. If you have ever found crumbs at the bottom of your cereal packet, or unpopped popcorn at the bottom of the box at the movies, you have seen this first hand.

What may be happening is that when the particles are bouncing around, the smaller particles are more likely to fit into any void that is created, and so they percolate downwards, resulting in a net movement of large particles upwards through the bulk. This has been measured experimentally and analytic models have been proposed for the case of only two distinct particle sizes. For a larger range of particle sizes, and for the case when particles can change size by being crushed, like in a packet of cereal, little is known.

Ultimately, my aim is to describe a flowing, polydisperse granular medium that has an evolving particle size distribution as a result of continual grain crushing due to shear deformation. To do this, I first need to describe - using continuum mechanics and population balance mechanics - the flow of these particles in a continuum sense. By then adding constitutive laws and breakage mechanics, the picture will be complete.

Particle size diagram

Publications

  • Benjy Marks, Pierre Rognon and Itai Einav. Grainsize dynamics of polydisperse granular segregation down inclined planes. Journal of Fluid Mechanics, doi:10.1017/jfm.2011.454, Published online by Cambridge University Press 14 November 2011.
  • Benjy Marks, Itai Einav and Pierre Rognon: Polydisperse Segregation Down Inclines: Towards Degradation Models of Granular Avalanches, Advances in Bifurcation and Degradation in Geomaterials, doi:10.1007/978-94-007-1421-2_19, vol. 11, p. 145–151, 2011.
  • Benjy Marks, Itai Einav. A cellular automaton for segregation during granular avalanches. Granular Matter,doi:10.1007/s10035-010-0247-y vol. 13, no. 3, p. 211-214, 2011.
  • M.J. Steel, Benjy Marks, Adel Rahmani. Properties of sub-diffraction limited focusing by optical phase conjugation. Optics Express, doi:10.1364/OE.18.001487, vol. 18, issue 2, p. 1487, 2010.
  • Benjy Marks, M.J. Steel, Adel Rahmani (2008). "Modelling time reversal experiments in the optical domain". OECC/ACOFT 2008 - Joint Conference of the Opto-Electronics and Communications Conference and the Australian Conference on Optical Fibre Technology, doi:10.1109/OECCACOFT.2008.4610639 , p. 1.

Learning & Teaching

  • CIVL2410 Soil Mechanics
  • CIVL2201 Structural Mechanics
  • ENGG1801 Engineering Computing
  • CIVL2810 Engineering Construction and Surveying