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Contribution à l'étude numérique de la ventilation naturelle dans des cavités ouvertes par la simulation des grandes échelles. Application au rafraîchissement passif des bâtiments

Abstract : Context : Air-conditioning represents a high-energy expenditure in the sector of the building, which could be reduced drastically through the use of passive cooling systems. In hot and humid climates, the passive cooling of premises is a tried and tested technique ordained around four principles : to minimize the external and internal heat transfers, to bring inertness to the buil- ding, to humidify the air, and to ensure a good convection in order to favor convective exchanges. Objective : The description of thermo-convective transfers (estimation of mass flows rate and heat transfers) set in open cavities (rooms with crossing ventilation, solar chimney, outer skin of a double facade,...) is still relatively uncommon and the stakes are high to improve passive systems. The study of these phenomena can be evaluated through computational fluid dynamics. This thesis's objectives are to achieve precise numerical simulations of airflow in specific configurations of passive systems in damp tropical climates, in order to improve and deepen our knowledge of natural convection and to begin to give information concerning the choice of numerical boundary conditions to apply to open geometries. Numerical approach : The numerical approach adopted in this work, to study the natu- ral turbulent convection, is the Large-Eddy Simulation. This approach is halfway between a direct numerical simulation and Reynolds-averaged Navier-Stokes equations. Such a technique is advantageous as it leads to a necessary substantial reduction of the number of discretization points compared to the technique of direct simulation requirements, while retaining the dynamic aspect of the flows. Results : The results obtained in this work refer to the study of the dynamic boundary conditions to impose in open geometries with SND and to the application of the LES to different configurations of open cavities with a turbulent flow, in order to characterize temperature and velocity fields and then deduce mass flow rate, enthalpy flow,. . . . The results have been compared either to other numerical results in the framework of national benchmarks (benchmark AmeTh and ADNBâti) or to experimental results.
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https://tel.archives-ouvertes.fr/tel-00763390
Contributor : Boris Brangeon <>
Submitted on : Monday, December 10, 2012 - 4:30:19 PM
Last modification on : Thursday, March 28, 2019 - 11:24:15 AM
Long-term archiving on: : Monday, March 11, 2013 - 12:45:55 PM

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  • HAL Id : tel-00763390, version 1

Citation

Boris Brangeon. Contribution à l'étude numérique de la ventilation naturelle dans des cavités ouvertes par la simulation des grandes échelles. Application au rafraîchissement passif des bâtiments. Mécanique des fluides [physics.class-ph]. Université de la Réunion, 2012. Français. ⟨tel-00763390⟩

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