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On the validity of the independence principle applied to the vortex-induced vibrations of a flexible cylinder inclined at 60 degrees

Bourguet, Rémi and Karniadakis, George E. and Triantafyllou, Michael S. On the validity of the independence principle applied to the vortex-induced vibrations of a flexible cylinder inclined at 60 degrees. (2014) Journal of Fluids and Structures, 53. 58-69. ISSN 0889-9746

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Official URL: http://dx.doi.org/10.1016/j.jfluidstructs.2014.09.005

Abstract

The vortex-induced vibrations (VIV) of a flexible cylinder inclined at 60 degrees are investigated by means of direct numerical simulation, at a Reynolds number equal to 500, based on the cylinder diameter and inflow velocity. The cylinder has a circular cross-section and a length to diameter aspect ratio equal to 50; it is modeled as a tension-dominated structure which is free to oscillate in the in-line and cross-flow directions. The behavior of the coupled fluid–structure system is examined for two values of the tension. Particular attention is paid to the validity of the independence principle (IP) which states that the inclined and normal-incidence body cases are comparable if the inflow velocity normal component is used to scale the physical quantities. The flexible cylinder exhibits regular VIV for both values of the tension. In the high tension configuration, where the in-line bending of the structure remains small, the IP is shown to be valid for the prediction of the cylinder responses and the fluid forces. In contrast, in the lower-tension configuration, the behavior of the fluid–structure system deviates from the IP. It is shown that this deviation is connected to the larger in-line bending of the structure which leads to considerably different profiles of the flow velocity locally perpendicular to the body in the inclined and normal cylinder cases. Since the system behavior appears to be mainly driven by this component of the flow, the profile modification induced by the larger in-line bending results in distinct responses: multi-frequency vibrations are observed in the inclined cylinder case whereas mono-frequency oscillations of larger amplitudes develop at normal incidence.

Item Type:Article
Additional Information:Thanks to Elsevier editor. The definitive version is available at http://www.sciencedirect.com The original PDF of the article can be found at Elsevier website : http://www.sciencedirect.com/science/article/pii/S0889974614002060
HAL Id:hal-01166472
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:Other partners > Brown University (USA)
French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT (FRANCE)
Other partners > Massachusetts Institute of Technology - MIT (USA)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UPS (FRANCE)
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Deposited By: Remi BOURGUET
Deposited On:22 Jun 2015 15:55

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