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The Rolling Transition in a Granular Flow along a Rotating Wall
Cemagref Grenoble, 2 rue de la Papeterie, St Martin d’Hères BP 76 38402, France
Cemagref Clermont-Ferrand, Domaine des Palaquins, Montoldre BP 03150, France
Institut Francais de Mécanique Avancée, Campus de Clermont-Ferrand, Les Cézeaux, Aubière Cedex BP265-63175, France
* Author to whom correspondence should be addressed.
Received: 19 September 2011; in revised form: 30 September 2011 / Accepted: 13 October 2011 / Published: 11 November 2011
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 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.
Keywords: granular flow; rheology; friction; spin; energetics; bifurcation
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Rioual, F.; Quiniou, A.L.; Lapusta, Y. The Rolling Transition in a Granular Flow along a Rotating Wall. Materials 2011, 4, 2003-2016.
Rioual F, Quiniou AL, Lapusta Y. The Rolling Transition in a Granular Flow along a Rotating Wall. Materials. 2011; 4(11):2003-2016.
Rioual, Francois; Quiniou, Aurélie Le; Lapusta, Yuri. 2011. "The Rolling Transition in a Granular Flow along a Rotating Wall." Materials 4, no. 11: 2003-2016.