Abstract A direct-forcing immersed boundary (DFIB) method with a virtual force is used to investigate the vortex-induced vibration (VIV) of an elastically mounted sphere in uniform flow at a moderate Reynolds number. A novel method is investigated to control VIV of an elastically mounted sphere by placing a small fixed sphere inline in tandem arrangement. The numerical method is validated by comparisons with previously published results for flow past a stationary sphere and for VIV phenomena. The influence of the small sphere diameter and the gap between the spheres on VIV are studied through an analysis of the hydrodynamic force coefficients, sphere responses, vortex shedding modes and energy efficiency. Regression analysis is conducted to propose mathematical relations for estimating the maximum values of hydrodynamic force coefficients and amplitude ratio. This study proves the capability of the DFIB model for investigating VIV of a sphere. It is also found that the small fixed sphere upstream increases the lift coefficient and amplitude ratio of the vibrating sphere while the drag coefficient is reduced. Furthermore, the energy efficiency of VIV of the sphere is found to be increased by up to three times due to the upstream small fixed sphere.

中文翻译：

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串联排列的固定小球体对球体VIV影响的数值研究

摘要 使用具有虚拟力的直接强迫浸入边界 (DFIB) 方法研究了弹性安装球体在中等雷诺数下均匀流动中的涡激振动 (VIV)。研究了一种通过将一个小的固定球体串联排列来控制弹性安装球体的 VIV 的新方法。该数值方法通过与先前公布的流过静止球体和 VIV 现象的结果进行比较来验证。通过对水动力系数、球体响应、涡旋脱落模式和能量效率的分析，研究了小球体直径和球体之间的间隙对VIV的影响。进行回归分析以提出估计水动力系数和振幅比的最大值的数学关系。本研究证明了 DFIB 模型在研究球体 VIV 方面的能力。还发现上游固定小球体增加了振动球体的升力系数和振幅比，而阻力系数降低。此外，发现由于上游小固定球体，球体的 VIV 的能量效率提高了三倍。