Vortex-induced vibrations of a flexible cylinder at large inclination angle
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Bourguet_Triantafyllou_PTA2015.pdf
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Author(s)
Bourguet, Remi
Triantafyllou, Michael S
Date Issued
December 2014
Journal
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
Publisher
Royal Society, The
Citation
Bourguet, R., and M. S. Triantafyllou. “Vortex-Induced Vibrations of a Flexible Cylinder at Large Inclination Angle.” Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 373, no. 2033 (December 15, 2014): 20140108–20140108.
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Author's final manuscript
Abstract
The free vibrations of a flexible circular cylinder inclined at 80° within a uniform current are investigated by means of direct numerical simulation, at Reynolds number 500 based on the body diameter and inflow velocity. In spite of the large inclination angle, the cylinder exhibits regular in-line and cross-flow vibrations excited by the flow through the lock-in mechanism, i.e. synchronization of body motion and vortex formation. A profound reconfiguration of the wake is observed compared with the stationary body case. The vortex-induced vibrations are found to occur under parallel, but also oblique vortex shedding where the spanwise wavenumbers of the wake and structural response coincide. The shedding angle and frequency increase with the spanwise wavenumber. The cylinder vibrations and fluid forces present a persistent spanwise asymmetry which relates to the asymmetry of the local current relative to the body axis, owing to its in-line bending. In particular, the asymmetrical trend of flow–body energy transfer results in a monotonic orientation of the structural waves. Clockwise and counter-clockwise figure eight orbits of the body alternate along the span, but the latter are found to be more favourable to structure excitation. Additional simulations at normal incidence highlight a dramatic deviation from the independence principle, which states that the system behaviour is essentially driven by the normal component of the inflow velocity.
MIT Department
Massachusetts Institute of Technology. Department of Mechanical Engineering
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DOI of Published Version
https://doi.org/10.1098/rsta.2014.0108
