Numerical Study of Combined Surface Radiation and Natural Convection in Vertical Conical Annular Enclosure

Abstract

The present study investigates the combined free convection and surface radiation in a conical annular cylinder filled with air (Pr=0.71). The steady-state continuity, Navier–Stokes and energy equations were carried out by the finite volume method, and the Discrete Ordinates Method (DOM) was used to solve the radiative heat transfer equation (RTE). The boundary conditions are such that the inner and the outer radius of cone are maintained at hot (Th) and cold (Tc) isothermal temperature. The horizontal upper and lower walls are assumed to be isolated. Concerning the radiation exchange, we consider that the fluid (air) is transparent, so only the solid surfaces contribute to the radiation exchange and assumed to be diffuse-gray. The computations are performed for Rayleigh number (Ra) in the range 103≤Ra≤106 , the surface emissivity (ε) 0≤ε≤1 and the cone angle () 63o, 76o, 80o and 84o. The key parameters for this analysis are considered as Rayleigh number (Ra), surface emissivity (ε) and the cone angle (). Results are presented in terms of isotherms, streamlines and the average Nusselt numbers.