Numerical simulation of flow-induced vibrations of tandem cylinders based on the Runge–Kutta method

This study investigates tandem cylinders and establishes a numerical simulation framework to evaluate flow-induced vibrations (FIV), examining their dynamic behavior across reduced velocities from 2 to 14 and spacing ratios from 1.5 to 2.5, which correspond to Reynolds numbers ranging between 1500 and 10,500. Firstly, a two-dimensional, two-degrees-of-freedom (2-DOF) fluid-structure interaction (FSI) model was established using the Runge-Kutta numerical method and the SST k-ω turbulence model, and validated against existing experimental data. Subsequently, the frequency responses, vibration characteristics, vortex-shedding patterns, and motion trajectories of tandem cylinders at three spacing ratios were numerically investigated and compared with those of a single cylinder. The results demonstrate that the proposed method effectively captures the vibration branches and typical vortex-shedding patterns involved in the FIV process. When the spacing is 1.5D, cylinder collisions occur, with the downstream cylinder exhibiting stronger vibrations and more chaotic trajectories. As spacing increases, the wake pattern transitions from 2S to 2T, with the downstream cylinder reaching a maximum dimensionless transverse amplitude of 1.71. Overall, the tandem configuration exhibits a much broader chaotic motion range than the single cylinder, indicating an amplification of FIV behavior.