No abstract

A numerical study of combined natural convection and radiation in a square cavity filled with a gray non-scattering semi-transparent fluid is conducted. The horizontal walls are adiabatic and the vertical are differentially heated. Convection is treated by the finite volumes approach and the discrete ordinates method is used to solve radiative transfer equation using S6 order of angular quadrature. Representative results illustrating the effects of the Rayleigh number, the optical thickness and the Planck number on the flow and temperature distribution are reported. In addition, the results in terms of the average Nusselt number obtained for various parametric conditions show that radiation modifies significantly the thermal behavior of the fluid within the enclosure.

Numerical investigation of combined laminar natural convection and volumetric radiation with internal heat generation is presented in this paper and computations are performed for a grey gas-filled square cavity whose horizontal walls are adiabatic and vertical walls are differentially heated. The convection is treated under Boussinesq approximation by an approach based on finite-volumes and the volumetric radiation by the discrete ordinates method. Flow and heat transfer characteristics through isotherms, streamlines and average Nusselt numbers have been presented for an external Rayleigh number 106, internal Rayleigh number 0 to 4x1012, optical thickness 0 to 10 and Albedo 0 to 1. Representative results illustrating the effects of the optical thickness and the internal heat generation on the flow and the temperature distribution within the cavity are presented. The results reveal that the fluid flow and heat transfer are influenced significantly by the volumetric radiation and the internal heat generation. By comparing the solutions in pure convection, the results in combined convection-volumetric radiation show that when the medium is participating, the effect of internal source presence is very important.