Thermohydrodynamic characteristics of combined double-diffusive radiation convection heat transfer in a cavity

Abstract

This work deals with the numerical analysis of a radiating gas flow caused by both temperature and buoyancy concentration gradients in a square cavity; in this regard, the set of governing equations, including conservation of mass, momentum, species, and energy are solved by a numerical technique. In terms of radiation, since the fluid is considered as a semitransparent medium, the radiative term in the energy equation appears and is calculated by numerical solving of the radiative transfer equation (RTE). Furthermore, all of the surrounding cavity walls are considered to be opaque, gray, and diffuse with constant emissivity. All of the flow equations are solved by the finite difference method (FDM) and the RTE by the discrete ordinate one (DOM). In the present study, an attempt is made to verify the optical thickness effects on flow, thermal behavior, and mass transform in a cavity flow, such that reciprocating trends were seen in this manner. Our numerical results show that the thermal field in double-diffusive convection flow reaches very fast its steady-state situation in comparison to the concentration distribution. Besides, it is found that the thermohydrodynamic characteristics of a double-diffusive convection flow of a radiating gas are much affected by optical thickness.