Abstract:

To reveal the features of flow structure and heat transfer and the mechanism of the non-Boussinesq liquid flow driven by thermal buoyancy in cavities, the natural convection of water in square and rectangular enclosures was numerically simulated with CFD software of Fluent.The effects of aspect ratio of the cavity, Rayleigh number, inclination angle and temperature difference between the two walls of the cavity on the flow and heat transfer were investigated.The results show that the flow pattern inverses if the two walls temperature of the cavity was greater and less than 3.98℃，respectively， at which the water density is maximum.The flow pattern inversion has a double vortex structure and decreases the average Nusselt number of natural convective heat transfer.At a fixed Rayleigh number, the average Nusselt number reaches a maximum in the square cavity at the aspect ratio of 1.The inclination of the square cavity has more complex influence on the average Nusselt number which depends not only on the Rayleigh number but also on the thermal boundary conditions.