Unsteady Natural Convection between Two Eccentric Hemispheres  

作　　者：Mariama Néné Koita Mamadou Lamine Sow Omar Ngor Thiam Vieux Boukhaly Traoré Cheikh Mbow Joseph Sarr Mariama Néné Koita;Mamadou Lamine Sow;Omar Ngor Thiam;Vieux Boukhaly Traoré;Cheikh Mbow;Joseph Sarr(Groupe de Recherche sur l’Energie Solaire et les Transferts (GREST), Faculté des Sciences et Techniques, Université Cheikh Anta DIOP (UCAD), Dakar, Sénégal;Laboratoire de Mécanique des Fluides, Faculté des Sciences et Techniques, Université Cheikh Anta DIOP (UCAD), Dakar, Sénégal)

机构地区：[1]Groupe de Recherche sur l’Energie Solaire et les Transferts (GREST), Faculté des Sciences et Techniques, Université Cheikh Anta DIOP (UCAD), Dakar, Sénégal [2]Laboratoire de Mécanique des Fluides, Faculté des Sciences et Techniques, Université Cheikh Anta DIOP (UCAD), Dakar, Sénégal

出　　处：《Open Journal of Applied Sciences》2021年第2期177-189,共13页应用科学（英文）

摘　　要：Natural convection heat transfer in open or closed cavities takes place in different engineering areas. The hemispherical cavity is a part of basic geometries although it is not widely studied. The present paper reports the numerical study of natural convection in a closed hemispherical annulus delimited by two vertically eccentric hemispheres filled with Newtonian fluid (air in this case with <em>Pr</em> = 0.7) is conducted. The inner hemisphere is heated by a heat flux of constant density and the outer one is maintained isothermal. Based on the Boussinesq assumptions, the governing equations are numerically studied using unsteady natural convection formulated with vorticity and stream-function variables. These equations are written by using bispherical coordinates system and solved by using a finite difference method. The effect of the control parameters such as the Rayleigh number (<span style="white-space:nowrap;">10³ ≤ <em>Ra</em> ≤ 10⁶</span>) or the eccentricity (<em>e</em> = ±0.2, ±0.5, 0) in the dynamic and thermal behaviours of the fluid is investigated.Natural convection heat transfer in open or closed cavities takes place in different engineering areas. The hemispherical cavity is a part of basic geometries although it is not widely studied. The present paper reports the numerical study of natural convection in a closed hemispherical annulus delimited by two vertically eccentric hemispheres filled with Newtonian fluid (air in this case with <em>Pr</em> = 0.7) is conducted. The inner hemisphere is heated by a heat flux of constant density and the outer one is maintained isothermal. Based on the Boussinesq assumptions, the governing equations are numerically studied using unsteady natural convection formulated with vorticity and stream-function variables. These equations are written by using bispherical coordinates system and solved by using a finite difference method. The effect of the control parameters such as the Rayleigh number (<span style="white-space:nowrap;">10³ ≤ <em>Ra</em> ≤ 10⁶</span>) or the eccentricity (<em>e</em> = ±0.2, ±0.5, 0) in the dynamic and thermal behaviours of the fluid is investigated.

关 键 词：Natural Convection Hemispherical Cavity Rayleigh Correlations ECCENTRICITY Nusselt Number 

分 类 号：O35[理学—流体力学]