Abstract The vortex induced vibration (VIV) mitigation on a circular cylinder with low mass ratio (i.e. the ratio of structural to displaced fluid mass) parameter and moderate Reynolds numbers through a nonlinear energy sink (NES) is investigated numerically as basis for applications on dynamics of spar platform, marine tunnel or risers used in the ocean engineering industry. The Reynolds-Averaged-Navier–Stokes (RANS) equations and shear Stress transport (SST) k – ω turbulence model are used to calculate the flow field, while a fourth-order Runge–Kutta method is employed for evaluating the nonlinear structure dynamics of flow–cylinder–NES coupled system. The computational model includes an overset mesh solution which can avoid the negative volume grid problem as a dynamic mesh method is involved to deform the domain according to the motion of the fluid–structure interface. The numerical model is validated against experimental data of VIV of an isolated cylinder in uniform current. The study is aimed to investigate the effect of NES parameters, including mass, damping and nonlinear cubic stiffness, and various reduced velocities on the VIV response of the cylinder. The VIV amplitudes’ distribution along the various reduced velocities, trajectories of cylinder motion, hydrodynamic response, and temporal evolution of vortex shedding, are obtained by conducting numerical simulations. Subsequently, it is found that placing a NES with appropriate parameters inside the cylinder, can affect the distribution of the three-branch response and narrows the lock-in range. A good VIV amplitudes’ suppression can be achieved with a large NES mass, small nonlinear cubic stiffness, and the NES damping is higher in the critical range for this kind low mass ratio cylinder structures.

中文翻译：

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中等雷诺数下具有非线性耗散振荡器的低质量比圆柱上的涡激振动

摘要 数值研究了通过非线性能量汇 (NES) 对具有低质量比（即结构与置换流体质量之比）参数和中等雷诺数的圆柱体的涡激振动 (VIV) 缓解进行了数值研究，作为动力学应用的基础。用于海洋工程行业的梁平台、海上隧道或立管。Reynolds-Averaged-Navier-Stokes (RANS) 方程和剪切应力传递 (SST) k – ω 湍流模型用于计算流场，而四阶 Runge-Kutta 方法用于评估非线性结构动力学流量-气缸-NES耦合系统。计算模型包括一个重叠网格解决方案，它可以避免负体积网格问题，因为涉及到动态网格方法，根据流固界面的运动使域变形。该数值模型针对均匀电流下孤立圆柱体的 VIV 实验数据进行了验证。该研究旨在研究 NES 参数（包括质量、阻尼和非线性三次刚度）以及各种降低速度对圆柱体 VIV 响应的影响。通过数值模拟获得了沿各种降低速度、圆柱体运动轨迹、流体动力学响应和涡旋脱落时间演化的 VIV 振幅分布。随后发现在圆柱体内放置一个参数合适的NES，可以影响三分支响应的分布并缩小锁定范围。较大的NES质量、较小的非线性立方刚度可以获得良好的VIV振幅抑制，这种低质量比圆柱结构在临界范围内NES阻尼较高。