A new regime of multiple states in free vibration of a cylinder at low Re

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• 作者：Navrose ; Sanjay Mittal ; ^{smittal@iitk.ac.in}
• 关键词：Vortex-induced vibration ; Lock-in ; Hysteresis
• 刊名：Journal of Fluids and Structures
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：68
• 期：Complete
• 页码：310-321
• 全文大小：1800 K
• 卷排序：68

文摘

The existence of multiple response in vortex-induced vibration of a circular cylinder is explored in the laminar flow regime by carrying out computations with different initial conditions for several mass ratios. In addition to primary and secondary hystereses near the ends of the lock-in regime, multiple states of the fluid-structure system exist in the middle of the lock-in regime as well. One of the two states is associated with large amplitude of cylinder oscillation. The response of the cylinder, for this state, lies on the classically known lower branch. In the other state, the cylinder exhibits low oscillation amplitude. Depending on the mass ratio and reduced speed this state may either be synchronized or desynchronized with the wake. A new branch of cylinder response has been identified for the lock-in state in this regime. The time histories of cylinder displacement and force coefficients on this branch are similar to that observed on the initial branch. In view of this, the new branch is referred to as initial branch (II)  . The variation of frequency of cylinder oscillation and phase between cylinder displacement and lift coefficient along IB(II)IB(II) is studied.