Fluid–thermal–structure interaction of three heated circular cylinders in tandem at a low Reynolds number of 150

The fluid–thermal–structure interaction of three identical, heated circular cylinders in tandem with a variable spacing ratio ranging from 4.0 to 10.0 is numerically investigated using the finite element method in this work. The vibration response and vorticity–temperature distribution are examined at the Prandtl number of Pr = 0.71 and the Reynolds number of Re = 150 in the reduced velocity range of 1.0 ≤ Ur ≤ 15.0. The numerical results indicate that the temperature distribution generally follows the vorticity clusters, presenting a distinct gradient in the wake. Four flow regimes are identified in terms of the interference of shear layers and vortex shedding, that is, continuous reattachment, alternate reattachment, quasi-identical shedding, and co-identical shedding, which are related to the reduced velocity and the spacing ratio. The middle and downstream cylinders experience the wake-induced vibration, and the wake-induced galloping occurs when Ur > 6. Compared with an isolated cylinder, the tandem configuration contributes to the drag reduction in the considered range of spacing ratio. Due to the wake interference, the time-averaged Nusselt number Numean is lower than that of an isolated cylinder. The heat transfer of the tandem cylinders is closely associated with their hydrodynamic behaviors.