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 1.5 D , 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.