Numerical Investigation of Three-Dimensional Fluid Flow and Heat Transfer from Finite Circular Cylinders in Tandem Arrangement

In this study, three-dimensional flow and heat transfer characteristics from finite circular cylinders of equal length are numerically investigated. Two finite circular cylinders of diameter D and aspect ratio AR=3 placed vertically on the computation domain's bottom wall (ground plane) are subjected to uniform external flow such that Re=20000 is attained. The distance between the cylinders S was varied as S=D, 2D, 4D. The turbulence model SST k- was used to solve the governing equations. Initially, a numerical verification study was carried out to determine the most suitable turbulence model and grid configuration using a single 3D cylinder for which data were available in the literature. Subsequently, the flow fields were obtained for two 3D cylinders arranged in a tandem. The main turbulence and flow characteristics appearing along the flow domain and on each cylinder surface were identified and presented in tabular form. The heat transfer effects of the flow over isothermal cylinders were evaluated using the mean and local Nusselt distributions, leading to recommendations for design improvements. While Kármán Street does not develop in the case of S/D=1 due to the observed irregular vortex separations, a stable Kármán Street is obtained for S/D=4. In terms of heat transfer, the highest heat transfer performance was observed in the case of S/D=1 for the upstream cylinder and S/D=4 for the downstream cylinder.