Natural convection of cold water near its density maximum in an elliptical enclosure containing a coaxial cylinder

A numerical study of natural convection heat transfer of cold water near its density maximum from a heated cylinder to its cooled coaxial elliptical enclosure is performed using finite volume method. The analysis is done for different Rayleigh number ranged from 103 to 106, density inversion parameter from 0 to 1, aspect ratio from 0.1 to 0.7, and elliptical ratio from 0 to 0.9 to investigate the effects of these parameters on flow and heat transfer characteristics. In addition, the effect of inclination angle is examined as well by turning the enclosure in the clockwise direction. When the stable flow transits to the unstable flow, the mechanism of oscillations is also discussed. Detailed analysis results for the distribution of streamlines, isotherms and Nusselt number are presented and an empirical heat transfer correlation was deduced within an acceptable uncertainty in this paper.