Free convection heat transfer from a concave hemispherical surface: A numerical exercise

Numerical investigation on a concave hemispherical surface to discover the thermo-fluid characteristics due to laminar free convection is carried out. In this study, numerical simulations of continuity, momentum, and energy equation are performed for the concave hemispherical surface using ANSYS FLUENT 19. The salient parameters such as the dimensionless radius of curvature of the hemispherical surface (from 1 to 5), Rayleigh number (from1.5 x 10(3) to 1.5 x 10(7)) and surface temperature (from 350 K to 500 K) is varied to perform a parametric study. It is observed that the Nusselt number rises with the Rayleigh number for the different radius of curvatures. However, with a rise in curvature radius, the heat transfer rate marginally increases at a lower Rayleigh number, whereas it steeply increases for higher Rayleigh number values. The variation of local heat transfer coefficient along the curved surface is displayed. The velocity vector field and temperature plume around the hemispherical body clearly illustrate the convection characteristics. A Nusselt number relationship is also obtained for the concave hemispherical surface, which was not reported earlier, and this relationship is accurate within +/- 6%.