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Comment coule une pâte granulaire? Etudes des composantes primaire et secondaire et des fluctuations de l'écoulement

Abstract : Wet granular materials are made of solid particles in high concentration, immersed in a viscous fluid. We investigated particle dynamics in a model granular suspension in Couette geometry, at low Reynolds/Taylor numbers for density and non density matched suspension. We used innovated techniques such as: Single Particle Tracking (SPT), Multi Particles Video Trajectography (MPVT) and Concentration Photometry (CP). These experiments allow us to provide information about single and collective motion of grains as well as particle repartition (local volume fraction). We investigated fully 3D velocity profiles in concentrated suspensions, diffusion coefficients, particle fluctuations and recirculation motion, also differential flows. We observe that the flow of non density matched suspensions is localized near the inner cylinder in the low shear rate regime, resulting in a sheared layer only a few particle diameters in thickness, in a way very similar to sheared dry granular materials. At high enough angular velocity, the initially localized flow crosses over to full fluidization: in this regime the granular suspension nearly behaves as a density-matched suspension. Dependence between particles' velocity and associated fluctuation amplitude is evidenced. Experiments as velocity and concentration profiles were compared with theoretical prediction based on the force balance model and different viscometric laws were investigated for normal and shear forces.
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Submitted on : Monday, November 12, 2012 - 11:32:17 AM
Last modification on : Thursday, January 11, 2018 - 6:14:59 AM
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  • HAL Id : tel-00750737, version 1



Octavian Blaj. Comment coule une pâte granulaire? Etudes des composantes primaire et secondaire et des fluctuations de l'écoulement. Fluid Dynamics [physics.flu-dyn]. Université Sciences et Technologies - Bordeaux I, 2012. English. ⟨tel-00750737⟩



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