Numerical analyses of buoyancy-driven flow with properties that depend on the local temperature

This paper described the numerical simulation results of natural convection for compressible fluids in a differentially heated square cavity with large temperature difference. The effects of temperature-dependent viscosity and thermal conductivity of air on natural convection were considered. The unsteady Navier-Stokes equations were solved for wide range of Rayleigh number (Ra) and temperature-difference (ΔT) by QUICK and SIMPLE methods. The results were compared with that of the Boussinesq approximation with constant properties. The effects of the non-Boussinesq approximation and temperature-dependent properties on the flow pattern and the heat transfer were discussed. Moreover, the difference between the Nusselt numbers obtained from the non-Boussinesq and the Boussinesq analyses in the wide range of Ra and ΔT were determined quantitatively. (author)