Consequences of using different pair-correlation funtions on the stability properties of the Homogeneous Cooling State for a monodisperse system of near-elastic disks

We show the differences in the stability properties of the Homogeneous Cooling State (HCS) of a two-dimensional monodisperse collection of rigid and near-elastic disks, obtained by using different formulae for the pair-correlation function.For an equation of state that takes into account the crystallization and ordering of the particles (and the respective pressure drop), the critical wavelength of the heat conduction mode is considerably modified in the transition zone, involving a bifurcation and an additional mode of instability. The theoretical predictions, using the improved equation of state are confirmed by numerical simulations. Nevertheless, some open questions remain

An investigation into clustering and segregation in granular materials

In this thesis, I studied the dynamics of granular matter by means of theory, simulations, and experiments. I studied how patterns emerge from a seemly unrelated ensemble of grains in different configurations. I focused on cluster formations in free cooling granular gases, developed an algorithm for cluster-cluster formation, and discovered a new way to control the segregation pattern in rotating tumblers, something with obvious practical importance

Shaping Segregation: Convexity vs. concavity

Controlling segregation is both a practical and a theoretical challenge. In this Letter we demonstrate a manner in which rotation-induced segregation may be controlled by altering the geometry of the rotating containers in which granular systems are housed. Using a novel drum design comprising concave and convex geometry, we explore a means by which radial size-segregation may be used to drive axial segregation, resulting in an order of magnitude increase in the axial segregation rate. This finding, and the explanations provided of its underlying mechanisms, could lead to radical new designs for a broad range of particle processing applications

Forced axial segregation in axially inhomogeneous rotating systems

Controlling segregation is both a practical and a theoretical challenge. Using a novel drum design comprising concave and convex geometry, we explore, through the application of both discrete particle simulations and positron emission particle tracking, a means by which radial size segregation may be used to drive axial segregation, resulting in an order of magnitude increase in the rate of separation. The inhomogeneous drum geometry explored also allows the direction of axial segregation within a binary granular bed to be controlled, with a stable, two-band segregation pattern being reliably and reproducibly imposed on the bed for a variety of differing system parameters. This strong banding is observed to persist even in systems that are highly constrained in the axial direction, where such segregation would not normally occur. These findings, and the explanations provided of their underlying mechanisms, could lead to radical new designs for a broad range of particle processing applications but also may potentially prove useful for medical and microflow applications