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Etude de la sédimentation de particules non-browniennes dans un fluide thixotrope à seuil : la laponite

Abstract : The settling of non-Bownian spheres in a laponite suspension has been studied experimentally. A specific preparation has been set up. The rheology of the fluid has been characterized~: a suspension of laponite constitutes a thixotropic, yield stress, shear thinning, viscoelastic fluid. The main characteristic is that the viscosity increases exponentially with the aging time. The settling of single spheres has been studied under different aspects : the velocity of the sphere, the flow field around the sphere and the birefringence induced by the settling sphere. The velocity of the sphere slows down exponentially with aging time. Two flow field patterns have been observed : with a negative wake (an upward motion in the wake of the sphere) or with a near fore-and-aft symmetry. The settling-induced birefringence relaxes slowly in the wake of the sphere. The characteristic relaxation time increases with the aging time exponentially. The settling of a couple of spheres has been observed in two cases : with and without a negative wake. Spheres may cluster in each case. A first experiment of a settling suspension has been made (a single size of small spheres). A settling on finite length has been observed with a kinetic described with an exponential.
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Contributor : Blandine Gueslin <>
Submitted on : Thursday, December 14, 2006 - 11:22:00 AM
Last modification on : Monday, December 14, 2020 - 9:51:23 AM
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  • HAL Id : tel-00120321, version 1


Blandine Gueslin. Etude de la sédimentation de particules non-browniennes dans un fluide thixotrope à seuil : la laponite. Dynamique des Fluides [physics.flu-dyn]. Université Pierre et Marie Curie - Paris VI, 2006. Français. ⟨tel-00120321⟩



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