Dual resonance in vortex-induced vibrations at subcritical and supercritical Reynolds numbers

Dahl, Jason; Hover, Franz S.; Triantafyllou, Michael; Oakley, Owen H.

doi:10.1017/s0022112009992060

Cited by 181 publications

(144 citation statements)

References 35 publications

(71 reference statements)

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“…The spanwise patterns developing once the cylinder oscillates are investigated in conditions naturally arising for a bluff body free to move in the current, by considering cases of vortex-induced vibrations (VIVs). The principal flow-structure interaction aspects of the problem have been examined in a previous work [34] and comparable systems have been studied by Jauvtis and Williamson [35], Dahl et al [36], Navrose and Mittal [37], and Cagney and Balabani [38]. Figure 2 shows the evolution of the body responses as a function of the reduced velocity U * , defined as the inverse of the nondimensional natural frequency of the oscillator.…”

Section: Introductionmentioning

confidence: 95%

Three-dimensional flow past a fixed or freely vibrating cylinder in the early turbulent regime

2018

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OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. This is an author-deposited version published in: http://oatao. The three-dimensional structure of the flow downstream of a circular cylinder, either fixed or subjected to vortex-induced vibrations, is investigated by means of numerical simulation, at Reynolds number 3900, based on the cylinder diameter and current velocity. The flow exhibits pronounced fluctuations distributed along the span in all studied cases. Qualitatively, it is characterized by spanwise undulations of the shear layers separating from the body and the development of vortices elongated in the plane normal to its axis (planar vortices). A quantitative analysis of crossflow vorticity fluctuations in the spanwise direction reveals a peak of fluctuation amplitude in the near region (i.e., area of formation of the spanwise wake vortices) and opposite trends of the spanwise wavelength in the shear layer and wake regions; the wavelength tends to decrease as a function of the streamwise distance in the shear layers down to a minimum value close to 0.5 body diameters and then slowly increases further in the wake. The spanwise structure of the flow is differently altered in these two regions, once the cylinder vibrates. In the shear layer region, body motion is associated with an enhancement of planar vortex formation. The amplification of vorticity spanwise fluctuations in this region is accompanied by a reduction of the spanwise wavelength; it is found to decrease as a function of the instantaneous Reynolds number based on the instantaneous flow velocity seen by the moving body, following the global trend of the wavelength versus Reynolds number previously reported for fixed cylinders. In the wake region, the flow spanwise structure is essentially unaltered compared to the fixed body case, in spite of the major distortions of the streamwise and crossflow length scales.

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Section: Introductionmentioning

confidence: 95%

Three-dimensional flow past a fixed or freely vibrating cylinder in the early turbulent regime

2018

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“…The fundamentals of VIV have been well documented for a cylinder whose axis in quiescient fluid is perpendicular to the oncoming flow (normal incidence case), the body being either rigid and elastically-mounted (King et al 1973;Bearman 1984Bearman , 2011Naudascher 1987;Mittal & Tezduyar 1992;Hover et al 1998;Okajima et al 2002;Sarpkaya 2004;Williamson & Govardhan 2004;Klamo et al 2006;Leontini et al 2006;Benaroya & Gabbai 2008;Lucor & Triantafyllou 2008;Dahl et al 2010;Navrose & Mittal 2013;Cagney & Balabani 2014;Konstantinidis 2014) or flexible (Trim et al 2005;Chaplin et al 2005;Lie & Kaasen 2006;Lucor et al 2006;Huera-Huarte & Bearman 2009, 2014; Vandiver et al 2009;Modarres-Sadeghi et al 2011;Bourguet et al 2011aBourguet et al ,b, 2012Bourguet et al , 2013a. VIV naturally appear both in the cross-flow direction and in the in-line direction, i.e.…”

Section: Introductionmentioning

confidence: 99%

The onset of vortex-induced vibrations of a flexible cylinder at large inclination angle

Bourguet

Triantafyllou

2016

J. Fluid Mech.

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The onset of the vortex-induced vibration (VIV) regime of a flexible cylinder inclined at 80 • within a uniform current is studied by means of direct numerical simulations, at Reynolds number 500, based on the body diameter and inflow velocity magnitude. A range of values of the reduced velocity, defined as the inverse of the fundamental natural frequency, is examined in order to capture the emergence of the body responses and explore the concomitant reorganization of the flow and fluid forcing. Additional simulations at normal incidence confirm that the independence principle, which states that the system behavior is determined by the normal inflow component, does not apply at such large inclination angle. Contrary to the normal incidence case, the free vibrations of the inclined cylinder arise far from the Strouhal frequency, i.e. the vortex shedding frequency downstream of a fixed rigid cylinder. The trace of the stationary body wake is found to persist beyond the vibration onset: the flow may still exhibit an oblique component that relates to the slanted vortex shedding pattern observed in the absence of vibration. This flow component which occurs close to the Strouhal frequency, at a high and incommensurable frequency compared to the vibration frequency, is referred to as Strouhal component; it induces a high-frequency component in fluid forcing. The vibration onset is accompanied by the appearance of novel, low-frequency components of the flow and fluid forcing, which are synchronized with body motion. This second dominant flow component, referred to as lock-in component, is characterized by a parallel spatial pattern. The Strouhal and lock-in components of the flow coexist over a range of reduced velocities, with variable contributions, which results in a variety of mixed wake patterns. The transition from oblique to parallel vortex shedding, that occurs during the amplification of the structural responses, is driven by the opposite trends of these two component contributions: the decrease of the Strouhal component magnitude, associated with the progressive disappearance of the high-frequency force component, and simultaneously, the increase of the lock-in component magnitude, which dominates once the fully-developed VIV regime is reached and the flow dynamics is entirely governed by wake-body synchronization.

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“…To capture the most influential effects of system nonlinearities, the first-order harmonic balance approach is applied. Due to the natural occurrence of a periodic 2:1 resonance of the cylinder X-Y response in a wide range of V r [11,38], it is reasonable to assume a periodic solution of cross-flow response (y) and vortex wake circulation (q) with a dimensionless resonant oscillation frequency (ω) as in Facchinetti et al [13], whereas the cylinder in-line motion (x) can be treated as a harmonic motion at 2ω. Accordingly, the approximated motions for x, y and q may be expressed as…”

Section: Analytical Prediction Of Controlled Responsesmentioning

confidence: 99%

“…Several experimental [11,23,38] and CFD [2,30] 2-DOF VIV studies have enabled the recently modified wake oscillator models to capture the experimentally observed hydro-elastic phenomena governing coupled cross-flow/in-line VIV alongside the lift/drag hydrodynamic features [41]. By using a CFD approach, Hasheminejad et al [19] recently proposed an adaptive fuzzy sliding mode controller for suppressing the 2-DOF VIV for a low-mass cylinder in a laminar flow with Re = 90.…”

Section: Introductionmentioning

confidence: 99%

Two-dimensional vortex-induced vibration suppression through the cylinder transverse linear/nonlinear velocity feedback

Srinil

2017

Acta Mech

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Suppressing vortex-induced vibration (VIV) has recently attracted numerous researchers due to its practical significance in many engineering applications. Most of the previous studies have focused on a passive or active flow control. A structurally active control approach to mitigate a two-dimensional, nonlinear coupled, cross-flow/in-line VIV has not been well studied. This paper presents a reduced-order fluid-structure dynamic model and combined analytical-numerical solutions for the efficient suppression of two-dimensional VIV of a flexibly mounted circular cylinder in uniform flows. The theoretical model is based on the use of coupled Duffing-Rayleigh oscillators with three variables describing the cylinder cross-flow/in-line displacements and the strength of the fluid vortex circulation in the cylinder wake. These equations of fluid-structure motions contain geometric and hydrodynamic nonlinearities. Closed-loop linear and nonlinear velocity feedback controllers are implemented in the transverse direction governing the larger cross-flow response than the associated in-line counterpart. Approximated analytical expressions are derived by using the harmonic balance to explicitly capture the system nonlinear dynamic features and the effects of key dimensionless parameters. Parametric investigations are carried out to evaluate the linear versus nonlinear controller performance in terms of the maximum response suppression capability and the power requirement in a wide range of reduced flow velocities, mass ratios, and control gains. Over the main lock-in resonance region with coupled cross-flow/inline responses, the linear controller is found to be more efficient in suppressing the two-dimensional VIV by also modifying the system frequencies and phase relationships. Nevertheless, based on the power comparison, the nonlinear control is superior to the linear control for very small targeted controlled amplitudes of a very low-mass cylinder. These active control strategies may be further applied to the multimode VIV suppression of a long flexible cylinder with multi degrees of freedom.

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Dual resonance in vortex-induced vibrations at subcritical and supercritical Reynolds numbers

Cited by 181 publications

References 35 publications

Three-dimensional flow past a fixed or freely vibrating cylinder in the early turbulent regime

Three-dimensional flow past a fixed or freely vibrating cylinder in the early turbulent regime

The onset of vortex-induced vibrations of a flexible cylinder at large inclination angle

Two-dimensional vortex-induced vibration suppression through the cylinder transverse linear/nonlinear velocity feedback

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