The influence of higher harmonic flow forces on the response of a curved circular cylinder undergoing vortex-induced vibration

Seyed-Aghazadeh, Banafsheh; Budz, Collin; Modarres‐Sadeghi, Yahya

doi:10.1016/j.jsv.2015.04.036

Cited by 33 publications

(12 citation statements)

References 30 publications

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“…Overall, the lock-in regions for each mode are relatively smaller for the curved cylinder in the convex orientation compared with those in the concave orientation, such that frequencies up to the seventh harmonic are excited in the convex orientation while frequencies up to the sixth harmonic are excited in the concave orientation. Similar extended lock-in ranges were previously observed in the VIV response of a 1 degree of freedom (DOF) flexibly mounted rigid curved cylinder in the concave orientation (Seyed-Aghazadeh et al 2015a). This extended lock-in range was associated with the range of reduced velocities for which higher harmonics of the flow forces dominated the response and the curved cylinder in the concave orientation was excited by these higher harmonic forces.…”

Section: The Overall View Of the Responsesupporting

confidence: 75%

“…At higher modes of 6 and 7, while the modal weights stay similarly low for low reduced velocities, the contributions from these modes increase for the convex orientation compared with those observed in the concave orientation. In previous studies of VIV of a flexibly mounted rigid curved cylinder, maximum amplitudes of oscillations have been observed to be in the same range for the concave and the convex orientations (Seyed-Aghazadeh et al 2015a).…”

Section: The Overall View Of the Responsementioning

confidence: 78%

“…an inclined cylinder (Jain & Modarres-Sadeghi 2013;Bourguet & Triantafyllou 2015;Han et al 2017;Seyed-Aghazadeh & Modarres-Sadeghi 2018), and those where the angle that the cylinder makes with the incoming flow varies continuously along its length, i.e. a curved cylinder (Assi et al 2014;Seyed-Aghazadeh, Budz & Modarres-Sadeghi 2015a), have helped to elucidate the effects of passive asymmetry introduced into the system through the structure on its VIV response. In the case of a curved cylinder, forming a quarter of a ring, the cylinder can be placed in two different orientations: the convex orientation in which the upper end of the cylinder sees the flow first and the concave orientation in which the lower end of the cylinder sees the flow first.…”

Section: Introductionmentioning

confidence: 99%

“…They have mentioned that the perturbation that triggers this unstable shedding mode is likely to be related to the fluctuation in the axial flow component. Later, experiments on VIV of a curved cylinder (a quarter of a ring), with no extension added to either end, and free to oscillate in the CF direction were conducted (Seyed-Aghazadeh et al 2015a). The amplitudes of oscillations in both the convex and the concave configurations were found to decrease compared with a vertical cylinder.…”

Section: Introductionmentioning

confidence: 99%

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An experimental investigation of vortex-induced vibration of a curved flexible cylinder

et al. 2021

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Vortex-induced vibration of a curved flexible cylinder placed in the test section of a recirculating water tunnel and fixed at both ends is studied experimentally. Both the concave and the convex orientations (with respect to the incoming flow direction) are considered. The cylinder was hung by its own weight with a dimensionless radius of curvature of $R/D=66$ , and a low mass ratio of $m^{*} = 3.6$ . A high-speed imaging technique was employed to record the oscillations of the cylinder in the cross-flow direction for a reduced velocity range of $U^{*} = 3.7 - 48.4$ , corresponding to a Reynolds number range of $Re= 165 - 2146$ . Mono- and multi-frequency responses as well as transition from low-mode-number to high-mode-number oscillations were observed. Regardless of the type of curvature, both odd and even mode shapes were excited in the cross-flow directions. However, the response of the system, in terms of the excited modes, amplitudes and frequencies of the oscillations, was observed to be sensitive to the direction of the curvature (i.e. concave vs convex), in particular at higher reduced velocities, where mode transition occurred. Hydrogen bubble flow visualization exhibited highly three-dimensional vortex shedding patterns in the wake of the cylinder, where there existed spatial and temporal evolution of the vortex shedding modes along the length of the cylinder. The time-varying intermittent vortex shedding in the wake of the cylinder was linked to the spanwise travelling wave behaviour of the vortex-induced vibration response. The observed spatially altering wake corresponded to the multi-modal excitation and mode transition along the length of the cylinder.

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Section: The Overall View Of the Responsesupporting

confidence: 75%

Section: The Overall View Of the Responsementioning

confidence: 78%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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An experimental investigation of vortex-induced vibration of a curved flexible cylinder

et al. 2021

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“…With the flow visualisation on a stationary curved cylinder at Re = 1000, such feature could be generated by another fluid-instability mechanism associated with the wake interference of the horizontal section located upstream. The decreased response due to the curvature effect was also observed by Seyed-Aghazadeh et al [17] who conducted a 1-DOF VIV experiment of convex/concave cylinders with R/D = 47 in a lower Re range of 300-2300. The extended cross-flow response was also reported in the concave case.…”

Section: Introductionsupporting

confidence: 71%

Experimental investigation on in-plane/out-of-plane vortex-induced vibrations of curved cylinder in parallel and perpendicular flows

Srinil

Zhang

2018

Journal of Sound and Vibration

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Newcastle University ePrints -eprint.ncl.ac.uk Srinil N, Ma B, Zhang L. Experimental investigation on in-plane/out-of-plane vortex-induced vibrations of curved cylinder in parallel and perpendicular flows. Abstract This study is motivated by an industrial need to better understand the vortex-induced vibration (VIV) of a curved structure subject to current flows with varying directions whose data for model calibration and validation are lacking. In this paper, new experimental investigations on the two-degree-of-freedom in-plane/out-of-plane VIV of a rigid curved circular cylinder immersed in steady and uniform freestream flows are presented. The principal objective is to examine how the approaching flow direction versus the cylinder curvature plane affects cross-flow and in-line VIV and the associated hydrodynamic properties. This is achieved by testing the curved cylinder in 3 different flow orientations comprising the parallel flows aligned with the curvature vertical plane in convex and concave configurations, and the flows perpendicular to the curvature plane. The case of varying flow velocities in a subcritical flow range with a maximum Reynolds number of about 50,000 is considered for the curved cylinder with a low mass ratio and damping ratio. Experimental results are presented and discussed in terms of the cylinder response amplitudes, inclination angles, mean displacements, motion trajectories, oscillation frequencies, hydrodynamic forces, relative phases, fluid excitation and added inertia coefficients. Comparisons with other experimental results of curved and straight cylinder VIV are also presented. The experiments highlight the important effects of cylinder curvature versus flow orientation on the combined cross-flow/in-line VIV. The maximum (minimum) responses occur in the perpendicular (convex) flow case whereas the extended lower-branch responses occur in the concave flow case. For perpendicular flows, some meaningful features are observed, including the appearances of cross-flow mean displacements and asymmetric eight-shaped motion trajectories due to multiple 2:1:1 resonances where two out-of-plane and one in-plane dominant frequencies are simultaneously excited. Overall VIV phenomena caused by the system asymmetry should be recognised in a prediction model and design codes to capture the combined effects of curved configuration and approaching flow direction. Keywords: Vortex-induced vibration (VIV), fluid-structure interaction, experimental investigation, curved cylinder, two-degree-of-freedom oscillation * Corresponding author: narakorn.srinil@newcastle.ac.uk; Tel. +44 191 208 6499; Fax +44 191 208 5491 Z Vertical direction in Fig. 1 based on right-hand rule δy Cylinder maximum global inclination angle from vertical axis and about pivot φx,φy Cylinder local inclination angle from the horizontal axis in Fig.1 θx, θy Phase difference between force moment and cylinder rotational response θxy Phase difference between in-line and cross-flow responses ξa System damping ratio in air ξw System dampin...

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On the Dynamic Response of Flow-Induced Vibration of Nonlinear Structures

Seyed-Aghazadeh

Samandari

Baf

2019

Nonlinear Structures and Systems, Volume 1

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The influence of higher harmonic flow forces on the response of a curved circular cylinder undergoing vortex-induced vibration

Cited by 33 publications

References 30 publications

An experimental investigation of vortex-induced vibration of a curved flexible cylinder

An experimental investigation of vortex-induced vibration of a curved flexible cylinder

Experimental investigation on in-plane/out-of-plane vortex-induced vibrations of curved cylinder in parallel and perpendicular flows

On the Dynamic Response of Flow-Induced Vibration of Nonlinear Structures

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