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Titre :
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A numerical and experimental investigation of stability of natural convective flows within a horizontal annulus
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Auteurs :
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M. Dyko ;
K. Vafai ;
A. Mojtabi
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Type de document :
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article/chapitre/communication
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Année de publication :
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1999
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Format :
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p. 27-61
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Langues:
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= Anglais
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Catégories :
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PHYSIQUE ETAT DE LA MATIERE
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Mots-clés:
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MECANIQUE DES FLUIDES
;
TRANSFERT DE CHALEUR
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Résumé :
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A numerical and experimental study of buoyancy-driven flow in the annulus between two horizontal coaxial cylinders at Rayleigh numbers approaching and exceeding the critical values is presented. The stability of the flow is investigated using linear theory and the energy method. Theoretical predictions of the critical Rayleigh number for onset of secondary flows are obtained for a wide range of radius ratio R and are verified by comparison with results of previous experimental studies. A subcritical Rayleigh number which provides a necessary condition for global flow stability is also determined. The three-dimensional transient equations of fluid flow and heat transfer are solved to study the manifestation of instabilities within annuli having impermeable endwalls, which are encountered in various applications. For the first time, a thorough examination of the development of spiral vortex secondary flow within a moderate gap annulus and its interaction with the primary flow is performed for air. Simulations are conducted to investigate factors influencing the size and number of post-transitional vortex cells. The evolution of stable three-dimensional flow and temperature fields with increasing Rayleigh number in a large gap annulus is also studied.
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Source :
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Journal of Fluid Mechanics, vol Vol 381
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