HEAT TRANSFERT AT THE ROUGHNESS SCALE IN TURBULENT RAYLEIGH-BÉNARD CONVECTION
Résumé
Turbulent convection is a spontaneous physical process present in many natural systems as well as in engineering applications. However most of these systems are non-ideal in terms of underlying surfaces involving specific topography or small-scale roughness. Moreover interactions between buoyant flow and plate roughness result in a global heat transfer enhancement and in some cases, in an increase of the heat transfer scaling exponent (see for ex. [2]). In this study, we consider thermal convection over a regularly roughened plate in a Rayleigh Bénard cell. The objective is to clarify inter- actions between the large scale circulation filling the box and the flow around the roughness elements by means of direct numerical simulations. Three successive heat transfer regimes are investigated from inactive roughness to a regime where the heat transfer relative increase is larger than the relative surface increase induced by roughness addition.
Domaines
Sciences de l'ingénieur [physics]
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