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Ecoulement granulaire à haute vitesse sous l'action de la force centrifuge. Application en agroenvironnement à la problématique de l'épandage

Abstract : This PhD Thesis focuses on the physical mechanisms in play during the interaction of a granular material with a rotating boundary. This configuration is inspired by the process of centrifugal spreading of fertilizer particles in agro-engineering. In the first part of this thesis, a dilute flow of particles has been considered. We study experimentally and theoretically the features of the trajectories involving friction, rolling and collisions for three kinds of particles of well characterized shape and a modelling of these trajectories is proposed by introducing a rolling friction coefficient calibrated by experiments. In the second part of this PHD thesis, we study using the discrete element method, the case of a dense granular flow of particles along a rotating boundary. The flow consists firstly of an impact followed by an elongation under the added action of the inertial forces (Centrifugal, Coriolis) and at last an independent motion of the particles. We show that the flow of particles is subjected to a complex strain rate involving traction, compression and to a less extent shear. We show that we can define at the continuum scale an effective friction coefficient of the granular flow along the boundary as a function of the degrees of freedom of the particles in the flow as well as their mechanical properties. We finish by addressing some open questions on tribology and contact mechanics in order to achieve a quantitative characterization of these flows for the different kinds of granules.
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Submitted on : Thursday, August 23, 2012 - 1:50:02 PM
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  • HAL Id : tel-00724951, version 1

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Aurélie Le Quiniou. Ecoulement granulaire à haute vitesse sous l'action de la force centrifuge. Application en agroenvironnement à la problématique de l'épandage. Biomécanique [physics.med-ph]. Université Blaise Pascal - Clermont-Ferrand II, 2009. Français. ⟨NNT : 2009CLF21977⟩. ⟨tel-00724951⟩

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