Abstract
This paper presents a numerical methodology for solving combined radiation-conduction-convection heat transfer problems in cylindrical geometries. The radiation heat transfer equations are discretized for a generalized cylindrical absorbing-emitting-scattering medium using the Discrete Exchange Factor (DEF) method. The accuracy of the method is demonstrated by comparing heat flux predictions to benchmark solutions and experimental results. Numerical simulations for two practical test cases extracted from ongoing research in thermal manufacturing are also included. The first example considers combined conduction-radiation heat transfer in sapphire fibers pulled from melt where the solid is cooled by volumetric radiation loss to the surroundings. Comparison of numerical results with analytical solutions based on singular perturbation analysis shows excellent agreement. The second example considers radiation and natural convection interactions in a cylindrical enclosure where because of the coupling between energy and flow equations through the buoyancy term, radiative heat transfer drastically modifies both the temperature and flow fields in the enclosure.
