Wake-Induced Vibration of a Flexible Plate Located in the Wake of a Circular Cylinder
- Huakun Wang (Hohai University) | Tianjiao Pan (Hohai University) | Yitong Chen (Hohai University) | Qiu Zhai (Hohai University)
- Document ID
- International Society of Offshore and Polar Engineers
- The 28th International Ocean and Polar Engineering Conference, 10-15 June, Sapporo, Japan
- Publication Date
- Document Type
- Conference Paper
- 2018. International Society of Offshore and Polar Engineers
- bending stiffness, flexible plate, gap spacing, Wake-induced vibration
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- 20 since 2007
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The wake-induced vibrations (WIVs) of a flexible plate behind a stationary circular cylinder are investigated numerically. A strongly coupled finite element model is utilized to solve the fluid-structure interaction (FSI) problem. The Reynolds number based on the free stream velocity U and the diameter of the cylinder D is 100. Numerical simulations are performed at four bending stiffness, KB=0.00563, 0.0225, 0.09 and 0.36 in the gap spacing range of 2.0≤S/D≤5.0. According to the numerical results, the fluid flow presents three patterns: (i) steady flow; (ii) vortex shedding behind the plate; and (iii) vortex shedding in the gap. No oscillation occurs in the steady flow, whereas significant vibration appears accompanied with the vortex shedding. For small gap spacing (S/D=2.0 and 3.0), the maximum vertical amplitude of the tip reaches its peak at KB=0.09, due to the resonance of the first-bending mode. Differently, for large gap spacing (S/D=4.0 and 5.0), the peak amplitude is found at KB=0.00563, where the comparison between the vibration frequency and the natural frequency of the plate implies the effect of both the first- and second-bending modes; it is also found that the plate vibration is nonlinear and the orbit of the tip presents a “Figure-8” shape instead of an arc. Finally, the flow fields around the critical spacing range are comprehensively analyzed to reveal the dynamic mechanisms between the flow and the flexible plate.
During the past few decades, vortex-induced vibration (VIV) of a flexible plate model has received much attention due to its importance in applications such as paper processing (Watanabe et al., 2002), fish locomotion (Lauder, 2015) and ocean energy harvesting (Jbaily and Jeung, 2015). Although these applications are widespread, the VIV problem still puzzles people due to its complicated dynamic mechanisms.
As a multi-physics issue, the VIV of a flexible plate involves the interactions between the fluid flow and the elastic body. Numerous studies have been performed to deal with this issue (Balint and Lucey, 2005; Eloy et al., 2007; Tang and Paϊdoussis, 2007, etc.). These results show that the flexible plate suddenly loses stability and attains intensified flapping motion beyond a critical flow speed; this change is usually attributed to a broken compromise between the unsteady pressure of the fluid and the bending stiffness of the plate. As an important branch, there also some studies concerning with WIV of a flexible plate behind a bluff body. Taylor et al. (2001) demonstrated continuous extraction of electrical energy from a plate made of piezoelectric membrane behind a bluff body. Furquan and Mittal (2015) performed a numerical study of flow past two square cylinders with deformable splitter plates. When the vibration frequency is close to the structural natural frequency, lock-in occurs. Purohit et al. (2017) focused on the effect of flow velocity and flexural rigidity on WIV of a flexible plate behind a square bluff body. For a particular combination of the two parameters, the coupled system shows resonance condition. It is worth noting that the configurations mentioned above are associated with an extraneously induced excitation, characterized by the fluid force due to the vortex shedding from the upstream bluff body. However, little research has focused on the effects of the upstream bluff body at different gap spacings, where the hydrodynamic force and the vibration response of the plate may differ significantly.
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