Effect of Prandtl Number on Natural Convection in Tilted Square Enclosure with Inner Circular Cylinder

A numerical analysis of the effect of the Prandtl number on the natural convection in a cold outer tilted square enclosure with an inner hot circular cylinder is presented. Several Prandtl numbers (Pr=0.1, 0.7, 7) are considered, with different angles(0 degrees, 15 degrees, 30 degrees, 45 degrees) for the enclosure and Rayleigh numbers (Ra=10(3), 10(4),10(5)). The effect of the Prandtl number on the natural convection is analyzed using isotherms and streamline and surface-averaged Nusselt numbers. The flow and heat transfer characteristics are found to be dependent on the time for Ra=10(5) and Pr=0.1 at angles of 0 degrees and 45 degrees. However, in the other cases, the flow and heat transfer characteristics are independent of the time.The surface-averaged Nusselt number increases with an increase in the Prandtl number. As the Prandtl number increases, the Nusselt number becomes larger regardless of the angle for Ra=10(5). In particular, the Nusselt number steeply increases when the angle is 45 degrees for Ra=10(5) and Pr=0.1.