Upward Flow and Heat Transfer Around Two Heated Circular Cylinders in Square Duct Under Aiding Thermal Buoyancy

Abstract

This paper presents a numerical investigation of mixed convection heat transfer around a pair of identical circular cylinders placed in side-by-side arrangement inside a square cavity of single inlet and outlet ports. The investigation provided the analysis of gradual effect of aiding thermal buoyancy on upward flow around cylinders and its effect on heat transfer rate. For that purpose, the governing equations involving continuity, momentum and energy are solved using the commercial code ANSYS-CFX. The distance between cylinders is fixed with half-length of cavity. The simulation is assumed to be in laminar, steady, incompressible flow within range of following conditions: Re = 1 to 40, Ri = 0 to 1 at Pr = 0.71. The main obtained results are shown in the form of streamline and isotherm contours in order to interpret the physical phenomena of flow and heat transfer. The average Nusselt number is also computed and presented. It was found that increase in Reynolds number and/or Richardson number increases the heat transfer. Also, aiding thermal buoyancy creates new form of counter-rotating zones between cylinders.

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“…They concluded that the maximum Nusselt number was obtained when the diameter of the cylinders was largest. Laidoudi [3] studied the heat transfer characteristics of two heated circular cylinders placed in a square enclosure. They claimed that the average Nusselt number, Nu increases with increasing Ri and Re numbers in the range of the study.…”

“…Figure 6. The distribution of isotherms for different configurations at Gr =10 3Figure6depicts the distribution of isotherms for the inclined square cylinder in the cavity at Gr =103 . The distribution of the isotherms is symmetrical concerning the center of the cylinder in all cases.…”