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Computational Thermal Sciences: An International Journal
ESCI SJR: 0.249 SNIP: 0.434 CiteScore™: 0.7

ISSN Печать: 1940-2503
ISSN Онлайн: 1940-2554

Computational Thermal Sciences: An International Journal

DOI: 10.1615/ComputThermalScien.2020028346
Forthcoming Article

Three-dimensional natural convection phenomena around a uniformly heated cubical body located at the center of a spherical enclosure.

Hedia welhezi
Faculty of Science of Tunis
Nader Ben-Cheikh
Faculty of Science of Tunis
Brahim Ben-Beya
Faculty of Science of Tunis

Краткое описание

This investigation addresses a systematic numerical method based on the finite volume method and a full multigrid technique to study three-dimensional natural convection phenomena around a heated cube placed inside a concentric air-filled spherical enclosure. In this work, we observed the flow structures and heat transfer characteristics in the enclosure according to the variation of the Rayleigh number. The computation is performed for Rayleigh number ranging from 102 to 106 and the Prandtl number is of Pr=0.71. Typical sets of streamlines and isotherms are presented to analyze the intricate circulatory flow patterns set up by the buoyancy force of the fluid. The variation of the local and the surface-averaged Nusselt numbers at the inner hot cube wall are also presented to exhibit the overall heat transfer characteristics inside the enclosure. It was found that, when the Rayleigh numbers are low, the isotherms are approximately parallel and the conduction is the dominant heat transfer mode. While, as Rayleigh number increases, buoyancy-induced convection heat transfer becomes dominant and the isotherms are squeezed because of the stronger convection effects. Results indicate also that optimal average heat transfer rate is obtained for Rayleigh number set to 102 for both cases of the spherical enclosure and inner cube.