In crystal growth autoclaves, dissolution zone and cristallisation zone are connected through a diaphragm. The flow regimes in such a configuration are quite complex, as they result from two buoyancy mechanisms, solutal and thermal, acting in opposite directions. In addition, the autoclave walls are thick and heat transfer in it strongly affect heat transfer in the bulk (conjugate problem).Several model with increasing difficulties have been numerically tested to calculate the bulk flow. For a thermal boundary condition with a flux imposed at the external wall, the temperature distlibution along the internal wall is found to be almost linear.For "thermosiphon" configuration, the axisymmetric solution is completely different, but still the flow goes up along the internal wall inside the two zones. For three-dimensional solutions, the flow is going up along the axis in the crystallisation zone; showing that the axisymmetric solution is not realistic.In addition, the stability theory indicates that after a certain threshold, the solution would become anti-symmetric and thus will be three-dimensional too.
OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible This is an author's version published in: http://oatao.univ-toulouse.fr/20680
To cite this version:Terhmina, Omar and Mojtabi, Abdelkader Ecoulements de convection forcée en régimes dynamique et thermique non établis dans un espace annulaire.
Ecoulements de convection forcée enrégimes dynamique et thermique non établis dans un espace annulaire O. TERHMINA et A. MOJT ABI Ecole Mohammadia d'lngenieurs, Avenue Ibn Sina, Agdal, Rabat, Maroc R ésumé----Ce travail a pour objet l'étude de l'écoulement laminaire de convection forcée en régimes dynamique et thermique non établis dans la région d'entrée d'un espace annulaire compris entre deux cylindres coaxiaux et isothermes. La résolution du problème a été faite par la méthode des différences fi nies. Ainsi nous avons obtenu les champs de vitesse et de température pour plusieurs combinaisons du rapport des rayons, du nombre de Reynolds, du nombre de Peclet et de la température du fl uide à l'entrée. Ce qui nous a permis d'établir des corrélations pour les longueurs d'établissement dynamique et thermique et d'analyser le transfert de chaleur au niveau des parois.
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