Analysis of radiative heat transfer in an absorbing-emitting-scattering medium using fluent

Abstract

Thermal radiation is transferred by electromagnetic waves or photons. Thermal radiation is a very complex phenomenon and although the governing equations are known but they are difficult to solve. The analysis of radiative heat transfer in presence of participating medium is very difficult because radiative intensity as function of position, direction, wavelength, temperature and time. In some cases, these dependencies are not straightforward.The transient term of the radiative transfer equation (RTE) can be neglected i.e. steady-state RTE assumption does not lead to significant errors, since the temporal variations of the observables are in the range of 10-9 to 10-15. The problem has been solved using the FLUENT software to analyze the radiative heat transfer problems, based on finite volume method (FVM). The available computational fluid dynamics software package FLUENT is applied to various test problems using DISCRETE ORDINATE MODEL (DOM MODEL) and the results obtained have been compared with other published results. The test problems include Isothermal Absorbing-Emitting medium in square enclosure, purely scattering medium in square and rectangular enclosure, three-dimensional heat generation in cuboid enclosure, collimated incidence in square enclosure, non-isothermal gray participating medium between two parallel surfaces and also anisotropically scattering gray planar medium in square enclosure. The medium is homogeneous and diffuse gray surface is used.The user defined function (UDF) has been written in C programming language for temperature profile, linear anisotropic phase function and Rayleigh phase function. The effect of absorption coefficient, scattering coefficient, scattering albedo, emissivity, anisotropic factor, grid size, angular discretization and angle of incidence on heat flux and temperature in the medium has been studied. The effect of Rayleigh phase function on heat flux has also studied.