Effect of Horizontal Spacing on Natural Convection Heat Transfer from Two Aligned Horizontal Cylinders in a Vented Enclosure

Natural convection heat transfer from horizontally aligned two heated cylinders placed inside a square vented enclosure has been investigated numerically for laminar flow. The Navier–Stokes equations and energy equations have been employed to simulate the flow and thermal behaviors with a finite volume (SIMPLE) method to represent and evaluate the partial differential equations in the form of algebraic equations using ANSYS–FLUENT 16.1 Package. The study has employed a range of Rayleigh numbers from 103 to 107 with the variation of horizontal spacing between two cylinders and symmetrical open vent size with constant enclosure width. The results displayed that the average Nusselt number is increased with the increase of the Rayleigh number, spacing between cylinders, and opening size. The maximum enhancement range for average Nu is between 50 and 100% for low Ra and 20–30% for high Ra with full opening size and large spacing size. The variation of the local Nusselt numbers, streamlines, and isotherms displayed the effect of the Rayleigh number, opening size, and spacing between cylinders on the flow and thermal behaviors.