MIXED CONVECTION HEAT TRANSFER IN POWER-LAW FLUIDS FROM PAIR OF CIRCULAR CYLINDERS IN CONFINED TANDEM ARRANGEMENT

Abstract

Mixed convection heat transfer from a pair of' horizontal circular cylinders in a tandem arrangement immersed in incompressible power-law fluid is considered herein under the steady flow regime. In this arrangement. the fluid is flowing in horizontal direction whereas gravity is acting downwards. which results in the cross buoyancy flow configuration where the buoyancy may be cross- adding or cross- opposing. The dependence of density on the temperature is accounted by the Bouissneq approximation. The temperature gradient between the cold fluid and hot bluff bodies is assumed to he low. The suitable forms of the continuity, momentum and thermal energy equations are solved by using the finite volume based solver ANSYS FLUENT. The convective terms in the momentum and energy equations are discretized using the QUICK scheme. The pressure-velocity decoupling is resolved using the SIMPLE scheme. The numerical solution of the flow governing equations are obtained for the I'ollowing ranges of the parameters. i.e.. Reynolds number (1 < Re< 40). and Prandtl number (I < Pr < 100), Richardson number. (0 < Ri < 2) and power-law index (0.2< n< 1.8). The effects of these dimensionless parameters on the detailed local and global kinematics of flow and heat transfer characteristics such as streamline. vorticity. pressure profiles. individual and total drag coefficients and local and average Nusselt numbers have been explored in this work. For fixed value of Ri. Re and Pr with increases the power law-index the value of Nusselt number and pressure drag coefficient for both cylinders is decrease, but viscous drag coefficient increases. If gap ratio is increases so both cylinders such as upstream and downstream work as the single cylinders. Nusselt number also showed a direct correlation with Reynolds number, with increasing value of Reynolds number the value of Nussclt number decreases drastically. For better representation of effects streamline profiles, isothermal profiles, and vorticity profile has been incorporated in this thesis