[Instabilités thermoconvectives dans les fluides supercritiques]
La première partie de l'article concerne la convection de Rayleigh–Bénard instationnaire dans de l'3He supercritique telle qu'elle apparaı̂t dans les conditions expérimentales de Meyer et Kogan (Phys. Rev. E 63 (2002) 056310). Cette étude est menée en résolvant numériquement les équations de Navier–Stokes couplées avec l'équation d'état linéarisée et celle de l'énergie. Les oscillations temporelles inattendues de la température ont été interprétées en terme de compétition entre les effets piston chaud et froid. Dans un deuxième temps, nous avons considéré la stabilité de deux couches superposées, chaude et froide d'un même fluide supercritique isobare en configuration instable. Les premiers résultats confortent bien l'idée de l'analogie entre la diffusion des espèces (instabilité de Rayleigh–Taylor) et la diffusion thermique considérée dans cette étude.
A numerical solution of the Navier–Stokes equations coupled with the energy and linearised equation of state has been performed in the unsteady Rayleigh–Bénard configuration for nearly supercritical 3He in the exact conditions with which Meyer and Kogan (Phys. Rev. E 63 (2002) 056310) performed their experiments. We propose an interpretation of the observed unexpected temperature oscillations at the convection onset in terms of coupled hot and cold piston effects. We have also considered the stability of two layers (hot and cold) of a same supercritical fluid in an unstable configuration. The first results show an analogy between the diffusion of species (Rayleigh–Taylor like instability) and thermal diffusion considered in this study.
Mot clés : Fluide supercritique, Effet piston, Instabilité
@article{CRMECA_2004__332_5-6_345_0,
author = {Sakir Amiroudine and Bernard Zappoli},
title = {Thermoconvective instabilities in supercritical fluids},
journal = {Comptes Rendus. M\'ecanique},
pages = {345--351},
publisher = {Elsevier},
volume = {332},
number = {5-6},
year = {2004},
doi = {10.1016/j.crme.2004.02.007},
language = {en},
}
Sakir Amiroudine; Bernard Zappoli. Thermoconvective instabilities in supercritical fluids. Comptes Rendus. Mécanique, Volume 332 (2004) no. 5-6, pp. 345-351. doi : 10.1016/j.crme.2004.02.007. https://comptes-rendus.academie-sciences.fr/mecanique/articles/10.1016/j.crme.2004.02.007/
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