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Etude analytique et numérique des instabilités spatio-temporelles des écoulements de convection
mixte en milieu poreux: comparaison avec l'expérience.

Abstract : This study deals with the spatio-temporal evolution of thermo-convective instabilities in porous media heated from below and subject to a horizontal through flow. The experimental data show that in laminar convection two kind of structures may appear depending on the parameters of problem: the moving transversal rolls (T.R) and the stationary longitudinal rolls (L.R). It is shown that while the prediction stemming from the linear temporal stability is in a complete contradiction with experiments, the border between convective and absolute instability correspond perfectly to the observed transition from L.R to T.R. Moreover it has also been found that the measured and the predicted of oscillations and the wavelength of T.R are in a good agreement at the absolute instability regime. The competition between T.R and L.R is examined in the framework on a model based on coupled amplitude equations. The numerical simulation of this model in presence of noise allow to understand some experimental observations. The direct two dimensional numerical simulation of this problem with spectral methods is performed and show that on linear effects do not modify some of the T.R characteristics. The mean heat transfer is also evaluated and compared for experimental data.
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https://tel.archives-ouvertes.fr/tel-00069550
Contributor : Alexandre Delache <>
Submitted on : Thursday, May 18, 2006 - 1:46:15 PM
Last modification on : Tuesday, November 24, 2020 - 2:18:05 PM
Long-term archiving on: : Saturday, April 3, 2010 - 11:24:45 PM

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Alexandre Delache. Etude analytique et numérique des instabilités spatio-temporelles des écoulements de convection
mixte en milieu poreux: comparaison avec l'expérience.. Dynamique des Fluides [physics.flu-dyn]. Université des Sciences et Technologie de Lille - Lille I, 2005. Français. ⟨tel-00069550⟩

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