Fluid Flow And Heat Transfer Around A Cylinder Submerged In The Wake Of Another Of Different Diameters

The paper investigated the flow-induced aerodynamics and heat transfer of an isothermal cylinder(diameter D = 0.04m) submerged in the wake of another insulation one(diameter d) in tandem arrangement. The simulation are proceeded at a various range of diameter ratio(d/D = 0.4, 0.6, 0.8, 1.0) and center-to-center distance ratio L*(= L/D, 1.2 ≤ L/D ≤ 5.0) for fixed Reynolds number(Re = 200, based on D) and Prandtl number(Pr = 0.7) using finite volume method.The objectives mainly focus on the upstream cylinder size and spacing ratio effects on total parameters including time-mean drag coefficient(CD), fluctuating drag and lift coefficients(CDf and CLf), Strouhal numbers(St), Nusselt number(Nu) of the downstream cylinder and flow structures. For a further understanding, the local parameters including fluctuating pressure coefficient, time-mean pressure coefficient and Nusselt number on the downstream cylinder and fluctuating and mean streamwise velocity in the gap and vortex contours are obtained. It can be observed that, the attendance of upstream cylinder can be regarded as a protector of the rear cylinder. The drag force can be effective reduced with large diameter ratio and small space ratio and declines by 99.7% at d/D = 0.8, L* = 3.0. But the occurrence of upstream cylinder is disadvantage to heat transfer compared with a single cylinder. Depending on the gap interference situation, four distinct flow patterns and the characteristics for each are introduced.