Natural Convection Between Two Horizontal Cylinders in an Adiabatic Circular Enclosure

A numerical study of natural convection flow structure and heat transfer has been undertaken for air around two horizontal, differentially heated cylinders confined to an adiabatic circular enclosure. Parametric simulations were performed to assess the effects of gap width between cylinders as well as the inclination angle of the enclosure with respect to gravity. Results clearly indicate that the fluid flow complexity and heat transfer characteristics of air amid the cylinders and enclosure wall are strongly affected by the Rayleigh number, the inclination angle, and the gap width between the cylinders. With the exception of the vertical orientation, heat exchange between the differentially heated cylinders is predominantly controlled by a counterclockwise recirculating flow enclosing them. In addition, flow visualization experiments were conducted for the physical configuration under consideration, and a generally good agreement for the flow pattern was observed between the predictions and the experiments, further validating the present numerical simulation.