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Title: Vortex-induced vibrations of a non-linearly supported rigid cylinder
Author: Bourdier, Sylvain
ISNI:       0000 0001 3472 2907
Awarding Body: University of Southampton
Current Institution: University of Southampton
Date of Award: 2008
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Vortex-Induced Vibrations (VIV) are a complex fluid-structure interaction problem. VIV are particularly strong for low-mass structures subject to a low damping, as encountered in the offshore industry, in which structures experiencing VIV can also be subject to strong structural non-linearities. In this project, investigation of the VIV of a low-mass low-damping rigid cylinder subject to structural non-linearities is carried out first experimentally. Non-linearities considered are the symmetric or asymmetric limitation of the amplitude of the cylinder with soft or stiff stops placed at different offsets from the cylinder and implying a non-smooth non-linearity of the system. Experimental results show that a strong perturbation of the dynamics of the cylinder occurs when amplitude limitation is strong, and flow visualisations displaying a modification of the vortex wake suggest a change in the fluid-structure interaction affecting the vortex formation process. Attention is also given to the impact velocities in the different cases of amplitude limitation with stiff stops, as they are an important factor in the design of structures. Two different wake oscillator models are then used to simulate the VIV of the same rigid circular cylinder in the same conditions of non-linear structural restraints. Results show that these simple models exhibit some features observed experimentally, giving in some cases a good estimation of the experimental data.
Supervisor: Chaplin, John Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: TA Engineering (General). Civil engineering (General)