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Vortex-induced vibrations of a cylinder with tripping wires

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dc.contributor.author Hover, F.S.
dc.contributor.author Tvedt, H.
dc.contributor.author Triantafyllou, M.S.
dc.date.accessioned 2005-08-23T06:03:19Z
dc.date.available 2005-08-23T06:03:19Z
dc.date.issued 2001
dc.identifier.uri http://hdl.handle.net/1721.1/25619
dc.description.abstract Thin wires are attached on the outer surface and parallel to the axis of a smooth circular cylinder in a steady cross-stream, modelling the effect of protrusions and attachments. The impact of the wires on wake properties, and vortex-induced loads and vibration are studied at Reynolds numbers up to 4.6 X 10^4, with 3.0 X 10^4 as a focus point. For a stationary cylinder, wires cause significant reductions in drag and lift coefficients as well as an increase in the Strouhal number to a value around 0.25-0.27. For a cylinder forced to oscillate harmonically, the main observed wire effects are: (a) an earlier onset of frequency lock-in, when compared with the smooth cylinder case; (b) at moderate amplitude/cylinder diameter (A=D) ratios (0.2 and 0.5), changes in the phase of wake velocity and of lift with respect to motion are translated to higher forcing frequencies, and (c) at A=D = 1:0, no excitation region exists; the lift force is always dissipative. The flow-induced response of a flexibly mounted cylinder with attached wires is significantly altered as well, even far away from lock-in. Parameterizing the response using nominal reduced velocity Vrn = U/fnD, we found that frequency lock-in occurs and lift phase angles change through 180deg at Vrn=4.9; anemometry in the wake confirms that a mode transition accompanies this premature lock-in. A plateau of constant response is established in the range Vrn = 5.1-6.0, reducing the peak amplitude moderately, and then vibrations are drastically reduced or eliminated above Vrn = 6.0. The vortex-induced vibration response of the cylinder with wires is extremely sensitive to angular bias near the critical value of Vrn = 6.0, and moderately so in the regime of suppressed vibration. en
dc.format.extent 616260 bytes
dc.format.mimetype application/pdf
dc.language.iso en_US en
dc.publisher Cambridge University Press en
dc.rights Copyright: Cambridge University Press This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder.
dc.subject vortex-induced en
dc.subject reynolds number en
dc.title Vortex-induced vibrations of a cylinder with tripping wires en
dc.type Article en
dc.identifier.citation Journal of Fluid Mechanics, 448, p.175-195 (2001) en


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