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
• 来源期刊: 应用科学(英文)
• 学科: 物理学
• 关键词: Natural Convection Hemispherical Cavity Rayleigh Correlations ECCENTRICITY Nusselt Number
• 年，卷（期）: 2021,（2）
• 页码范围: 177-189
• 页数: 13页
• 分类号: O35

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.