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Theses
Erosion, transport et instabilités d'un lit de particules dans un tube
Erosion, transport et instabilités d'un lit de particules dans un tube
Abstract : We have studied experimentally the evolution of a particle bed submitted to a pipe flow. Depending on the experimental parameters, we have put in evidence five different regimes for the bed evolution : still particles, flat bed in motion, laminar dunes, vortex dunes and apparition of sinuous dunes. This work is divided into four main parts. After a qualitative study of the different regimes, we have studied the incipient motion of the particles. Particles at the surface of the bed can move as soon as hydrodynamic forces acting on them exceed a fraction of their apparent weight. This corresponds to a critical Shields number that we have found to be constant over a large range of small particle Reynolds number. We have used a two phase model with a solid friction rheology for the particle phase to describe the bed-load transport as well as the erodible-bed instability. Calculations are performed numerically but also analytically in asymptotic cases. The theorical bed load transport gives a good prediction of the flat bed temporal evolution and the predicted thresholds of laminar dunes formation, which corresponds to a constant Reynolds number, accounts reasonably well for the experimental observations. Finally, we present the different regimes of bed evolution in a phase diagram.
https://tel.archives-ouvertes.fr/tel-00202496
Contributor : Malika Ouriemi <>
Submitted on : Monday, January 7, 2008 - 11:35:53 AM
Last modification on : Thursday, January 18, 2018 - 1:26:48 AM
Long-term archiving on: : Tuesday, April 13, 2010 - 4:24:44 PM
Contributor : Malika Ouriemi <>
Submitted on : Monday, January 7, 2008 - 11:35:53 AM
Last modification on : Thursday, January 18, 2018 - 1:26:48 AM
Long-term archiving on: : Tuesday, April 13, 2010 - 4:24:44 PM