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Special Issue "Advances in the Dynamics of Granular Materials"

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A special issue of Materials (ISSN 1996-1944).

Deadline for manuscript submissions: closed (30 June 2011)

Special Issue Editor

Guest Editor
Prof. Dr. Hayley H. Shen (Website)

Department of Civil and Environmental Engineering, Clarkson University, Potsdam, NY 13699-5710, USA
Fax: +1-315-268-7985
Interests: granular media; constitutive relations; transitional flows; internal structures; ice formation in a wave field; water wave propagation through a pancake ice field

Special Issue Information

Dear Colleagues,

Stationary or quasi-static granular mechanics have been a part of the traditional soil mechanics for centuries. In contrast, moving granular materials has not received comparable scientific attention until much later. An intense growth of research in the dynamics of granular materials has been observed in the past several decades. The field has now become truly multi-disciplinary, including all engineering disciplines and physics, with recent interactions with chemical, biological, and human sciences. Due to the dissipative nature of grain interactions, the dynamics of granular materials display many surprising characteristics. Flowing granular materials act like a fluid. However, without external excitation, this fluid “freezes” to become a solid. The transition between phases, unlike ordinary materials, eludes a description based on currently available thermodynamic. Likewise, moving granular materials display rich mixing/de-mixing that has no observed analogues in ordinary fluids. The above phenomena are known for the simplest granular flows where the grains only exert contact forces to each other. When compounded with long range, such as electrostatic and magnetic, forces, the richness and complexity of phenomena drastically increase. The field of dynamic granular materials may provide a platform for a dialog amongst all researchers in studying discrete systems with complex interactions.

Prof. Dr. Hayley H. Shen
Guest Editor

Keywords

  • granular
  • dynamics
  • micromechanics
  • discrete systems

Published Papers (2 papers)

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Research

Open AccessArticle The Rolling Transition in a Granular Flow along a Rotating Wall
Materials 2011, 4(11), 2003-2016; doi:10.3390/ma4112003
Received: 19 September 2011 / Revised: 30 September 2011 / Accepted: 13 October 2011 / Published: 11 November 2011
PDF Full-text (895 KB) | HTML Full-text | XML Full-text
Abstract
The flow of a dry granular material composed of spherical particles along a rotating boundary has been studied by the discrete element method (DEM). This type of flow is used, among others, as a process to spread particles. The flow consists of [...] Read more.
The flow of a dry granular material composed of spherical particles along a rotating boundary has been studied by the discrete element method (DEM). This type of flow is used, among others, as a process to spread particles. The flow consists of several phases. A compression phase along the rotating wall is followed by an elongation of the flow along the same boundary. Eventually, the particles slide or roll independently along the boundary. We show that the main motion of the flow can be characterized by a complex deformation rate of traction/compression and shear. We define numerically an effective friction coefficient of the flow on the scale of the continuum and show a strong decrease of this effective friction beyond a certain critical friction coefficient μ*. We correlate this phenomenon with the apparition of a new transition from a sliding regime to a rolling without sliding regime that we called the rolling transition; this dynamic transition is controlled by the value of the friction coefficient between the particle and the wall. We show that the spherical shape for the particles may represent an optimum for the flow in terms of energetic. Full article
(This article belongs to the Special Issue Advances in the Dynamics of Granular Materials)
Open AccessArticle Simulation of Granular Flows and Pile Formation in a Flat-Bottomed Hopper and Bin, and Experimental Verification
Materials 2011, 4(8), 1440-1468; doi:10.3390/ma4081440
Received: 17 June 2011 / Revised: 11 August 2011 / Accepted: 12 August 2011 / Published: 22 August 2011
Cited by 2 | PDF Full-text (2597 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Granular flows of 200 μm particles and the pile formation in a flat-bottomed hopper and bin in the presence of air and in a vacuum were predicted based on three-dimensional numerically empirical constitutive relations using Smoothed Particle Hydrodynamics and Computational Fluid Dynamics [...] Read more.
Granular flows of 200 μm particles and the pile formation in a flat-bottomed hopper and bin in the presence of air and in a vacuum were predicted based on three-dimensional numerically empirical constitutive relations using Smoothed Particle Hydrodynamics and Computational Fluid Dynamics methods. The constitutive relations for the strain rate independent stress have been obtained as the functions of the Almansi strain including the large deformation by the same method as Yuu et al. [1]. The constitutive relations cover the elastic and the plastic regions including the flow state and represent the friction mechanism of granular material. We considered the effect of air on the granular flow and pile by the two-way coupling method. The granular flow patterns, the shapes of piles and the granular flow rates in the evolution are compared with experimental data measured under the same conditions. There was good agreement between these results, which suggests that the constitutive relations and the simulation method would be applicable for predicting granular flows and pile formation with complex geometry including free surface geometry. We describe the mechanisms by which the air decreases the granular flow rate and forms the convergence granular flow below the hopper outlet. Full article
(This article belongs to the Special Issue Advances in the Dynamics of Granular Materials)

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