TITLE:
Unsteady Natural Convection between Two Eccentric Hemispheres
AUTHORS:
Mariama Néné Koita, Mamadou Lamine Sow, Omar Ngor Thiam, Vieux Boukhaly Traoré, Cheikh Mbow, Joseph Sarr
KEYWORDS:
Natural Convection, Hemispherical Cavity, Rayleigh Correlations, Eccentricity, Nusselt Number
JOURNAL NAME:
Open Journal of Applied Sciences,
Vol.11 No.2,
February
23,
2021
ABSTRACT: 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 Pr = 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 (103 ≤ Ra ≤ 106) or the eccentricity (e = ±0.2, ±0.5, 0) in the dynamic and thermal behaviours of the fluid is investigated.