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Hétérogénéité de l'écoulement de fluides à seuil : approche phénoménologique et modélisation élasto-plastique

Abstract : This thesis deals with the modelisation of heterogeneous flows of yield stress fluids. in a first part, we propose a phenomenolgical model that couples mechanical properties of a fluid to a generalised Maxwell law. The simple system of equations thus obtained describes a complex phenomenology. We then devised an elastoplastic model that enables a better microscopic understanding of the flow. To build this model, a problem of elasticity is first solved, which yields an exact analytical expression of the perturbation due to a single plastic event in an elastic, homogeneous, isotropic medium, in an infinite and in a finite geometry. Finite sizes effects, and wall effects are thus characterised. The elastoplastic model is eventually numerically solved in a biperiodic geometry, and in a geometry confined by walls. At large shear rates; the flow is homogeneous. At lower shear rates, a complex spatio temporal organisation is observed. Remarkably, the dimension of the spatio-temporal organisation decreases when the shear rate in increased. An intermittent localisation of the flow in the vicinity of walls is also evidenced.
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https://tel.archives-ouvertes.fr/tel-00005119
Contributor : Guillemette Picard <>
Submitted on : Wednesday, February 25, 2004 - 6:58:53 PM
Last modification on : Saturday, September 26, 2020 - 11:44:03 PM
Long-term archiving on: : Friday, April 2, 2010 - 9:11:07 PM

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  • HAL Id : tel-00005119, version 1

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Guillemette Picard. Hétérogénéité de l'écoulement de fluides à seuil : approche phénoménologique et modélisation élasto-plastique. Dynamique des Fluides [physics.flu-dyn]. Université Paris-Diderot - Paris VII, 2004. Français. ⟨tel-00005119⟩

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