Numerical study of laminar natural convection heat transfer from a hemisphere with adiabatic plane and isothermal hemispherical surface

This work numerically studied laminar natural convection heat transfer from a hemisphere with the downward adiabatic flat and isothermal hemispherical surface in the range of Grashof numbers 10≤Gr≤106 and for Prandtl number of 0.72. The comprehensive results consisting of the streamlines and isothermal contours, temperature and velocity profiles, as well as local and average Nusselt numbers, have been presented with different Grashof numbers, and compared with the case of the hemisphere that all surfaces are isothermal. They reveal that at low Grashof numbers, although the plane is adiabatic, there exists the temperature boundary layer in the vicinity of the plane. Furthermore, the above local Nusselt numbers along the curved surface are greater than those of the isothermal hemisphere at different Grashof numbers. Correspondently, the average Nusselt number increases with the increasing of the Grashof numbers, which is smaller than that of the isothermal hemisphere. Finally, the correlating equation of the average Nusselt number with the Grashof number at different thermal conditions for the hemisphere has been obtained, which provide a valid prediction for the case of natural convection heat transfer from the hemisphere to dispose of applications in several fields of engineering, particularly those electrical cooling.