Numerical Investigation of Natural Convection Heat Transfer from a Cylinder in a Vented Enclosure

In this work, Natural convection heat transfer from a horizontal cylinder placed in a vented enclosure was investigated numerically to infer the effect of Rayleigh number (Ra) having the values 1*10 4 , 5*10 4 and 1*10 5 , the effect of the ratio of the enclosure width to the cylinder diameter (W/D) having the values 1.5, 1.75, 2, 2.25, 2.5, 2.75, 3 and 3.5, the effect of the ratio of the vent size to the enclosure width (O/W) for a range starting from 0 for a closed enclosure to 1 for an enclosure having two vertical walls only, and the effect of time variation, on the Nusselt number (Nu), the mass flow-rate, the flow and temperature patterns as well as the boundary layers, where the results showed that, Nu. number always increased with Ra. Number. Furthermore, Nu. number increased with the increase of the ratio W/D for ratios of O/W greater than 0.25, and Nu. number decreases with the increase of W/D for the range below this value.