Thermo-dynamic irreversibility induced by natural convection in square enclosure with inner cylinder. Part-I: Effect of tilted angle of enclosure

Two-dimensional numerical simulations were conducted to investigate the natural convection heat transfer induced by the temperature difference between cold walls of the tilted square enclosure and a hot inner circular cylinder for different Prandtl numbers (10−2 ⩽ Pr ⩽ 102) and Rayleigh numbers (103 ⩽ Ra ⩽ 106). The numerical solutions are obtained using an accurate and efficient immersed boundary method. The outer square enclosure is tilted from γ = 0° to γ = 45° by each 5°. Detailed analysis results including the distribution of streamlines, isotherms and Nusselt numbers are presented. The entropy generation and corresponding Bejan number in the enclosure are analyzed to estimate the thermo-dynamic irreversibility accompanied by the natural convection in the system.