Influence of initial conditions on granular dynamics near the jamming transition

Windows-Yule, Kit; Rosato, Anthony; Rivas, Nicolas; Parker, D.J.

doi:10.1088/1367-2630/16/6/063016

Cited by 16 publications

(8 citation statements)

References 62 publications

(62 reference statements)

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“…Nonetheless, the continued close correspondence observed between experiment and simulation for the (lower density) 15 particle case, where the system is unlikely to experience inelastic collapse, strongly suggests that the contact models used, and the relevant parameters chosen, are indeed adequate to emulate the experimental situation. Further support for the validity of the simulations used is provided by the consistent accuracy with which this model has been shown to capture the behaviour of similar experimental systems in previous studies, where the strongly driven, low density beds explored exist far from the limit of inelastic collapse [57][58][59][60][61].…”

Section: Discrete Particle Simulations-mercurydpmsupporting

confidence: 56%

“…once agreement between experiment and simulation has been demonstrated) using the known, experimental ε values, it is then possible to investigate the specific influence of ε by changing this particular parameter whilst holding all other variables fixed at the values known to successfully reproduce the experimental situation. The frictional coefficient is taken as μ = 0.1 [38], a value previously shown to provide accurate results in similar systems [57], and the contact time, t c , is implemented as 10 −6 s. The appropriateness of our chosen t c value was confirmed by performing repeated runs using values of t c a factor of 10 above and below this value and ensuring consistency in the resultant data.…”

Section: Discrete Particle Simulations-mercurydpmmentioning

confidence: 99%

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Resonance effects on the dynamics of dense granular beds: achieving optimal energy transfer in vibrated granular systems

et al. 2015

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Using a combination of experimental techniques and discrete particle method simulations, we investigate the resonant behaviour of a dense, vibrated granular system. We demonstrate that a bed of particles driven by a vibrating plate may exhibit marked differences in its internal energy dependent on the specific frequency at which it is driven, even if the energy corresponding to the oscillations driving the system is held constant and the acceleration provided by the base remains consistently significantly higher than the gravitational acceleration, g. We show that these differences in the efficiency of energy transfer to the granular system can be explained by the existence of resonances between the bed's bulk motion and that of the oscillating plate driving the system. We systematically study the dependency of the observed resonant behaviour on the system's main, controllable parameters and, based on the results obtained, propose a simple empirical model capable of determining, for a given system, the points in parameter space for which optimal energy transfer may be achieved. been demonstrated [15] that, for relatively shallow, strongly fluidized systems, this assumption does not necessarily hold true; rather, the dynamic properties of a vertically vibrated granulate are additionally sensitive to the specific combinations of f and A used to produce a given v, S or Γ. In other words, two systems vibrated with the same input energy achieved using two differing combinations of f and A may exhibit strongly disparate properties. Similarly, it is found that two systems driven with markedly different S and/or Γ values may possess near-identical internal energies, in direct contradiction of the monotonic relations one might expect.Specifically, for dilute systems such as those described in [15], it was found that an increase in A at fixed S resulted in an increase in the total energy possessed by the excited granulate. This greater energy transfer from the vibrating system to the granular bed at large driving amplitudes was attributed to the observed increase in the particle-base collision rate with increasing A. In other words, the lack of a simple, monotonic relationship between a granulate's kinetic and/or potential energy and any of the individual parameters v S , or Γ can be explained by the fact that such parameters do not provide sufficient information regarding certain key variables, in this case the particle-base collision rate within the system. As such, in order to accurately characterize the steady-state of such a system, one requires a pair of driving variables, f and A-in addition, of course, to a knowledge of the system's depth and dissipative properties.Recent works by Pugnaloni et al [16,17] have similarly challenged the assumption that a system's steady state may be adequately defined by a single parameter, in this instance for the case of a granular bed excited by a series of discrete taps, as opposed to continuous vibration. Specifically, it was, until recently, a generally held belief [18,19] that ...

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Section: Discrete Particle Simulations-mercurydpmsupporting

confidence: 56%

Section: Discrete Particle Simulations-mercurydpmmentioning

confidence: 99%

Resonance effects on the dynamics of dense granular beds: achieving optimal energy transfer in vibrated granular systems

et al. 2015

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“…The experimental domain is bounded by six solid walls. For both particles and walls, the frictional coefficient is taken as 0.1 m = , a value which has been shown to accurately reproduce experimental results in vibrated systems using the same software employed here [70,71]. The implementation of this value of μ also adds to the generality of our results, as a number of easily available materials which are commonly used in experiment (for example glass, steel, acrylic) share a similar friction coefficient of 0.1 m~ [72].…”

Section: The Simulated Systemmentioning

confidence: 99%

Convection and segregation in fluidised granular systems exposed to two-dimensional vibration

Windows-Yule

2016

New J. Phys.

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Convection and segregation in granular systems not only provide a rich phenomenology of scientifically interesting behaviours but are also crucial to numerous 'real-world' processes ranging from important and widely used industrial procedures to potentially cataclysmic geophysical phenomena. Simple, small-scale experimental or simulated test systems are often employed by researchers in order to gain an understanding of the fundamental physics underlying the behaviours of granular media. Such systems have been the subject of extensive research over several decades, with numerous system geometries and manners of producing excitation explored. Energy is commonly provided to granular assemblies through the application of vibration-the simplicity of the dynamical systems produced and the high degree of control afforded over their behaviour make vibrated granular beds a valuable canonical system by which to explore a diverse range of phenomena. Although a wide variety of vibrated systems have been explored in the existing literature, the vast majority are exposed to vibration along only a single spatial direction. In this paper, we study highly fluidised systems subjected to strong, multi-directional driving, providing a first insight into the dynamics and behaviours of these systems which may potentially hold valuable new information relevant to important industrial and natural processes. With a particular focus on the processes of convection and segregation, we analyse the various states and phase transitions exhibited by our system, detailing a number of previously unobserved dynamical phenomena and system states.

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“…For these systems, the relevant parameter determining mean flux through the orifice is the maximum velocity of the vibrating motion [7,8]. In vibrated beds of particles, jamming behaviors are typically history dependent [9] with the nonlinear response of the system dominated by contact-breaking due to the purely repulsive interaction between grains [10]. Under shear, the stress in both vibrated and non-vibrated granular materials is non-monotonic as a function of strain rate, with vibration reducing static shear strength, while still exhibiting history dependence for relatively high vibrations [11].…”

Section: Introductionmentioning

confidence: 99%

Planar granular shear flow under external vibration

Hoppmann

Utter

2017

Phys. Rev. E

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We present results from a planar shear experiment in which a two-dimensional horizontal granular assembly of pentagonal particles sheared between two parallel walls is subjected to external vibration. Particle tracking and photoelastic measurements are used to quantify both grain scale motion and interparticle stresses with and without imposed vibrations. We characterize the particle motion in planar shear and find that flow of these strongly interlocking particles consists of transient vortex motion with a mean flow given by the sum of exponential profiles imposed by the shearing walls. Vibration is applied either through the shearing surface or as bulk vertical vibration of the entire shearing region with dimensionless accelerations Γ=A(2πf)^{2}/g≈0-2. In both cases, increasing amplitude of vibration A at fixed frequency f leads to failure of the force network, reduction in mean stress, and a corresponding reduction in imposed strain. Vibration of the shearing surface is shown to induce the preferential slipping of large-angle force chains. These effects are insensitive to changes in frequency in the range studied (f=30-120 Hz), as sufficiently large displacements are required to relieve the geometrical frustration of the jammed states.

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Influence of initial conditions on granular dynamics near the jamming transition

Cited by 16 publications

References 62 publications

Resonance effects on the dynamics of dense granular beds: achieving optimal energy transfer in vibrated granular systems

Resonance effects on the dynamics of dense granular beds: achieving optimal energy transfer in vibrated granular systems

Convection and segregation in fluidised granular systems exposed to two-dimensional vibration

Planar granular shear flow under external vibration

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