TRANSIENT CHARACTERISTICS OF COUPLED THERMAL RADIATION AND NATURAL-CONVECTION IN A 3-D CYLINDRICAL CAVITY CONTAINING A HEATED PLATE

In this study, a numerical study of transient combined natural-convection and surface radiation in a cylindrical cavity with a heated plate placed inside is carried out using the open-source platform OpenFOAM. The effects of the Rayleigh number (105 < Ra < 107), inclination angle (0o < & phi; < 90)o, and surface emissivity (0 < & epsilon; < 1) on the velocity components, temperature field, and Nusselt number are investigated in detail. Results show that the Rayleigh number has a greater effect on the radiative heat transfer than on natural-convection. Radiative heat transfer increases monotonously with the increase of surface emissivity, and its contribution could be over 50% of the total heat transfer rate. The inclination angle of the plate affects the flow structure, but the difference in total Nusselt number is less than 10% for various inclination angles. Results in this study provide insights into the transient characteristics of coupled thermal radiation and natural-convection in a 3-D cavity and will guide the optimal design of related devices.