Instability in a Sand Heap

Évesque, P.; Rajchenbach, Jean

doi:10.1103/physrevlett.62.44

Cited by 350 publications

(183 citation statements)

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“…Since φ and are inhomogeneous in the vertical direction due to gravity, using a layer warrants that we focus on a region where a few macroscopic variables can describe the macrostate without the presence of significant spatial variations of the mean φ and in the region. Additionally, the free surface of the column of grains is not horizontal in general, especially for wide cells as described by others [4,9,24,25] (see also Fig. 2).…”

Section: Analysis Regionsmentioning

confidence: 78%

Relevance of system size to the steady-state properties of tapped granular systems

2015

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We investigate the steady-state packing fraction φ and force moment tensor of quasi-two-dimensional granular columns subjected to tapping. Systems of different height h and width L are considered. We find that φ and , which describe the macroscopic state of the system, are insensitive to L for L > 50d (with d the grain diameter). However, results for granular columns of different heights cannot be conciliated. This suggests that comparison between results of different laboratories on this type of experiments can be done only for systems of same height. We show that a parameter ε = 1 + (Aω) 2 /(2gh), with A and ω the amplitude and frequency of the tap and g the acceleration of gravity, can be defined to characterize the tap intensity. This parameter is based on the effective flight of the granular bed, which takes into account the h dependency. When φ is plotted as a function of ε, the data collapses for systems of different h. However, this parameter alone is unable to determine the steady state to be reached since different can be observed for a given ε if different column heights are considered.

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Section: Analysis Regionsmentioning

confidence: 78%

Relevance of system size to the steady-state properties of tapped granular systems

2015

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“…This can be achieved by vibration of vessels [10] or in fluidized beds [11]. The same effect can be obtained by means of external driving forces acting locally on each particle [12].…”

Section: Introductionmentioning

confidence: 99%

“…A simple mechanism for thermostatting the system is to assume that the particles are subjected to random kicks [12], what mimics the effects of shaking or vibrating the vessel [10]. If this stochastic force has the properties of a white noise [cf.…”

Section: Non-gaussian Thermostatmentioning

confidence: 99%

Computer simulation of uniformly heated granular fluids

Montanero¹,

Santos²

2000

Granular Matter

182

346

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“…The formations of a spontaneous heap [4][5][6][7] and convection cells [8][9][10][11][12] under vibration, and the segregation of particles [13][14][15][16][17][18] are just a few examples. These phenomena are consequences of unusual, and often complex, dynamical responses of the system.…”

Section: Introductionmentioning

confidence: 99%

Density waves in the flows of granular media

Lee

1994

Phys. Rev. E

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We study density waves in the flows of granular particles through vertical tubes and hoppers using both analytic methods and molecular dynamics (MD) simulations. We construct equations of motion for quasi one-dimensional systems. The equations, combined with the Bagnold's law for friction, are used to describe the time evolutions of the density and the velocity fields for narrow tubes and hoppers. The solutions of the equations can have two types of density waves, kinetic and dynamic. For tubes, we can show the existence of kinetic waves, and obtain the condition for dynamic waves for tubes from the equations. For hoppers, we obtain the solutions of the equations up to the first order of the opening angle, which also show the existence of kinetic waves. We reproduce density waves in the MD simulations for tubes. The waves are believed to be kinetic based on a few evidences, including a well defined flux-density curve. In MD simulations of flows in hoppers, we find density waves, which are also believed to be kinetic. 05.40+j, 46.10+z, 62.20-x Typeset using REVT E X 1

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Instability in a Sand Heap

Cited by 350 publications

References 1 publication

Relevance of system size to the steady-state properties of tapped granular systems

Relevance of system size to the steady-state properties of tapped granular systems

Computer simulation of uniformly heated granular fluids

Density waves in the flows of granular media

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