Effects of attached flexible splitter plates on flow-induced vibration of two tandem circular cylinders: Two-degree of freedoms study

Flow-induced vibrations (FIV) of two tandem elastically mounted circular cylinders with attached flexible splitter plates are simulated numerically. The Reynolds number and the density ratio are set as Re = 150 and 10, respectively. Other parameters of the plate are set as: non-dimensional length (lp/D = 2), and non-dimensional thickness (h/lp = 0.1). The cylinders are formulated by two-degree freedom (2DOF) model. For each cylinderplate body, the mass ratio and damping ratio are set as mr = 10 and zeta = 0.0, respectively. The study covers a wide range of reduced velocity (3 <= ur <= 18) and two center-to-center distances between the cylinders (5D and 7D). In each center-to-center distance, the effects of reduced velocity on hydrodynamic coefficients, displacement amplitudes, and the vortex shedding pattern, are explored. Results indicate that the flexibility of the plate significantly affects the vibration regime of the cylinder, so that the cylinder vibrations at low flexibility values are of the FIV type, at medium flexibility values they are of the stable vibrations type and at high flexibility values they are of the galloping type. It was also observed that the trajectory motion of the upstream cylinder is mostly in the form of an apparent 8, but the trajectory motion of the downstream cylinder is very complicated.