Numerical simulation of compressible high gradient thermobuoyant flow in square enclosures with localized heating from below

In this paper a numerical study of compressible free convection flow in square enclosures with localized heating from below and symmetrical cooling from the vertical side walls is performed. The temperature gradient between the hot and cold sources is not low so the Boussinesq approximation cannot be applied. To impediment the compressibility effect of the fluid, the ideal gas model has been used to determine the density field. Also the fluid properties are temperature dependent and are specified using Sutherland's law. The results of the compressible flow have been compared to those of incompressible fluid and it is found that the flow and temperature fields in the enclosure vary significantly due to the fluid compressibility and depend on the temperature gradient magnitude. The results of this study show that variable density-based algorithms should apply in domains of high thermobuoyant flow instead of classical Boussinesq-based method.