The effect of bionic fish swimming on the vortex-induced vibration (VIV) of a circular cylinder arranged in tandem at a low Reynolds number of 150 is numerically investigated in this work. The bionic fish placed upstream of the cylinder with gap ratios of 1, 3, and 5 and that located downstream of the cylinder with gap ratios of 3 and 5 are examined in the simulations that were carried out in the reduced velocity range of Ur = 2–15. It is found that both the gap ratio and the reduced velocity have a significant influence on the VIV response and wake flow structure. When the bionic fish is placed upstream, the maximum response amplitude of the downstream cylinder is much greater than that of an isolated one. Two flow regimes are identified in terms of the shear layer reattachment, i.e., the continuous reattachment and the alternate reattachment. Comparing the vortex shedding frequencies of the cylinder and the swimming fish, it is found that the frequency of the cylinder is always locked in the fish swimming frequency, and multiple frequencies occur at Ur = 5. When the bionic fish is arranged downstream, four flow regimes are observed, including the extended-body, continuous reattachment, alternate attachment, and co-shedding regimes. Furthermore, the time-mean energy transfer coefficient of the cylinder is considerably higher at Ur = 5 than that when the fish is placed upstream of the cylinder.

中文翻译：

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仿生鱼游动对串联圆柱体涡激振动影响的数值研究

这项工作对仿生鱼游动对串联排列的低雷诺数 150 圆柱体的涡激振动 (VIV) 的影响进行了数值研究。在 Ur = 2 的降低速度范围内进行的模拟中，检查了放置在间隙比为 1、3 和 5 的圆柱体上游的仿生鱼以及位于间隙比为 3 和 5 的圆柱体下游的仿生鱼。 –15。研究发现间隙比和折减速度对VIV响应和尾流结构都有显着影响。当仿生鱼置于上游时，下游圆柱体的最大响应幅度远大于孤立圆柱体的最大响应幅度。根据剪切层再附着，确定了两种流动状态，即连续再附着和交替再附着。对比圆柱体和游动鱼的涡旋脱落频率，发现圆柱体的频率始终锁定在鱼游动频率上，并且在Ur=5处出现多个频率。当仿生鱼布置在下游时，四流观察到的机制包括延伸体、连续重新附着、交替附着和共同脱落机制。此外，在 Ur = 5 时，圆柱体的时间平均能量传递系数比鱼放置在圆柱体上游时的要高得多。