Author(s)

Mariama Néné Koita^1,2, Mamadou Lamine Sow^1,2, Omar Ngor Thiam², Vieux Boukhaly Traoré¹, Cheikh Mbow^1,2, Joseph Sarr^1,2

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

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.

Natural Convection, Hemispherical Cavity, Rayleigh Correlations, Eccentricity, Nusselt Number

Koita, M. , Sow, M. , Thiam, O. , Traoré, V. , Mbow, C. and Sarr, J. (2021) Unsteady Natural Convection between Two Eccentric Hemispheres. Open Journal of Applied Sciences, 11, 177-189. doi: 10.4236/ojapps.2021.112012.