Combined thermal radiation and natural convection in a cavity containing a discrete heater: Effects of nature of heating and heater aspect ratio

This paper investigates the interaction between thermal radiation and natural convection in an air filled square cavity with a discrete heater placed inside. The vertical walls of the cavity are cooled while the horizontal ones are insulated. Two types of the heater, viz., isothermal and heat generating are considered. The governing coupled nonlinear partial differential equations were solved using a finite volume method on a uniformly staggered grid system. The effects of the pertinent parameters such as the Rayleigh number, aspect ratio of the discrete heater and surface emissivity on the heat and fluid flow characteristics are investigated in detail. In general it is found that the overall heat transfer rate is enhanced with an increase of the surface emissivity and the Rayleigh number for both isothermal and heat generating heaters. Buoyancy induced flow gets augmented for the isothermal solid body whereas it is weakened for the heat generating body in the presence of radiation exchange.