Vortex-induced vibrations of a freely vibrating cylinder near a plane boundary:: Experimental investigation and theoretical modelling

de Oliveira Barbosa, J.M.; Qu, Y.; Metrikine, A.; Lourens, E.

doi:10.1016/j.jfluidstructs.2017.01.002

Vortex-induced vibrations of a freely vibrating cylinder near a plane boundary:

Title

Vortex-induced vibrations of a freely vibrating cylinder near a plane boundary:: Experimental investigation and theoretical modelling

Author

de Oliveira Barbosa, J.M. (TU Delft Offshore Engineering)
Qu, Y. (TU Delft Offshore Engineering)
Metrikine, A. (TU Delft Offshore Engineering; TU Delft Applied Mechanics)
Lourens, E. (TU Delft Offshore Engineering)

Date

2017

Abstract

This work reports on experiments that were performed with a freely vibrating cylinder exposed to currents and placed near a plane boundary parallel to the cylinder axis. It is observed that the proximity of the boundary affects the vertical response of the cylinder in two ways: (i) for gaps between 0.75 and 2 diameters (D), the amplitude of oscillation is reduced; (ii) for gaps smaller than 0.75D, the cylinder impacts the boundary, resulting in an increase of amplitudes and frequencies of oscillations as the flow is accelerated. The in-line force acting on the cylinder is also examined, and the dependency of its harmonic components on the flow velocity and distance to the boundary is evaluated. Besides the typical amplification of the mean component inside the lock-in region, it is also observed that as the cylinder is placed closer to the boundary, the harmonic component with the frequency of the vertical oscillations increases, while the component with twice that frequency decreases in similar amount.

Based on the experimental observations, an existing wake-oscillator model for vortex-induced vibrations is enhanced in order to account for the effect of the boundary. The proposed model introduces an effective damper that is activated when the cylinder reaches a certain distance from the boundary, and a damper/spring set representing the rigidity of the boundary and the dissipation of energy due to impact.

Subject

Vortex-induced vibrations
Fluid-structure interaction
Wake-oscillator

To reference this document use:

http://resolver.tudelft.nl/uuid:90fcfe78-3f59-4d31-9ff3-bf980bd675ea

DOI

https://doi.org/10.1016/j.jfluidstructs.2017.01.002

Embargo date

2019-01-19

ISSN

0889-9746

Source

Journal of Fluids and Structures, 69, 382-401