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Equations continues pour l'étude de la dynamique des écoulements granulaires denses hétèrogènes

Abstract : avalanches, involve a wide range of different solid constituents that are immersed in an ambient fluid. In order to obtain a good representation of these flows, the interaction mechanisms among the different constituents of the mixture should be considered. In this research, it was developed a theoretical framework based on the mixture theory for representing the dynamics of a dense heterogeneous granular flow composed by a number of solid species with different properties, and immersed in a Newtonian ambient fluid. These fully coupled equations were solved numerically and validated by comparing the numerical results with experimental measurements of gravitational granular flows, triggered by the collapse of two-dimensional granular columns in ambient air or water. This theory was then used to investigate the ambient fluid effects on homogeneous granular flow dynamics, and the segregation effects on the dynamics of binary mixtures of small and large spherical particles of equal mass density. Our results suggest that the model equations include the essential features that describe the dynamics of dense heterogeneous granular flows. In particular, it is shown that segregation of the granular material increases the front speed because of the volumetric expansion of the flow. This increase in flow speed is damped by the ambient fluid, and this behavior is more pronounced in water compared to the case in air. It is concluded that a realistic model of dense heterogeneous granular flows should consider at least three constituents: large and small grains, and the ambient fluid.
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  • HAL Id : tel-00719232, version 1

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Carolina Meruane. Equations continues pour l'étude de la dynamique des écoulements granulaires denses hétèrogènes. Volcanologie. Université Blaise Pascal - Clermont-Ferrand II; Université du Chili, 2010. Français. ⟨NNT : 2010CLF22031⟩. ⟨tel-00719232⟩

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