Flow-induced vibration on a circular cylinder in planar shear flow

Tu, Jiahuang; Zhou, Dai; Bao, Yan; Fang, Congqi; Zhang, Kai; Li, Chunxiang; Han, Zhaolong

doi:10.1016/j.compfluid.2014.08.007

Cited by 26 publications

(15 citation statements)

References 54 publications

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“…This phenomenon was also reported in previous works under comparable symmetry breaking (e.g. Tu et al 2014). The ellipsoidal trajectories would be counter-clockwise for β < 0.…”

Section: Low Shear: Regime Vlsupporting

confidence: 65%

“…Shear parameters up to 0.4 were studied by Singh & Chatterjee (2014) and Zhang et al (2014), for a single value of the reduced velocity. Tu et al (2014) considered different values of the reduced velocity but a maximum shear parameter equal to 0.1. Previous works thus provide a partial vision of the flow-structure system behaviour in the shear parameter-reduced velocity domain.…”

Section: Introductionmentioning

confidence: 99%

“…Through numerical simulations, Singh & Chatterjee (2014), Tu et al (2014) and Zhang et al (2014) studied the impact of the shear on VIV. They reported that the structural response amplitudes tend to increase with the shear parameter.…”

Section: Introductionmentioning

confidence: 99%

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Vortex-induced vibrations of a cylinder in planar shear flow

2017

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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.univ-toulouse.fr/ Eprints ID : 18137 The system composed of a circular cylinder, either fixed or elastically mounted, and immersed in a current linearly sheared in the cross-flow direction, is investigated via numerical simulations. The impact of the shear and associated symmetry breaking are explored over wide ranges of values of the shear parameter (non-dimensional inflow velocity gradient, β ∈ [0, 0.4]) and reduced velocity (inverse of the non-dimensional natural frequency of the oscillator, U * ∈ [2, 14]), at Reynolds number Re = 100; β, U * and Re are based on the inflow velocity at the centre of the body and on its diameter. In the absence of large-amplitude vibrations and in the fixed body case, three successive regimes are identified. Two unsteady flow regimes develop for β ∈ [0, 0.2] (regime L) and β ∈ [0.2, 0.3] (regime H). They differ by the relative influence of the shear, which is found to be limited in regime L. In contrast, the shear leads to a major reconfiguration of the wake (e.g. asymmetric pattern, lower vortex shedding frequency, synchronized oscillation of the saddle point) and a substantial alteration of the fluid forcing in regime H. A steady flow regime (S), characterized by a triangular wake pattern, is uncovered for β > 0.3. Free vibrations of large amplitudes arise in a region of the parameter space that encompasses the entire range of β and a range of U * that widens as β increases; therefore vibrations appear beyond the limit of steady flow in the fixed body case (β = 0.3). Three distinct regimes of the flow-structure system are encountered in this region. In all regimes, body motion and flow unsteadiness are synchronized (lock-in condition). For β ∈ [0, 0.2], in regime VL, the system behaviour remains close to that observed in uniform current. The main impact of the shear concerns the amplification of the in-line response and the transition from figure-eight to ellipsoidal orbits. For β ∈ [0.2, 0.4], the system exhibits two well-defined regimes: VH1 and VH2 in the lower and higher ranges of U * , respectively. Even if the wake patterns, close to the asymmetric pattern observed in regime H, are comparable in both regimes, the properties of the vibrations and fluid forces clearly depart. The responses differ by their spectral contents, i.e. sinusoidal versus multi-harmonic, and their amplitudes are much larger in regime VH1, where the in-line responses reach 2 diameters (0.03 diameters in uniform flow) and the cross-flow responses 1.3 diameters. Aperiodic, intermittent oscillations are found to occur in the transition region between regimes VH1 and VH2; it appears that wake-body synchronization persists in this case.

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“…This phenomenon was also reported in previous works under comparable symmetry breaking (e.g. Tu et al 2014). The ellipsoidal trajectories would be counter-clockwise for β < 0.…”

Section: Low Shear: Regime Vlsupporting

confidence: 65%

Section: Introductionmentioning

confidence: 99%

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Vortex-induced vibrations of a cylinder in planar shear flow

2017

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“…13(a). The same phenomenon was also observed in our previous work [28]. With the increasing of / , the multiple vibration frequency components of the transverse direction with those of the inline one and the dominant vibration frequency in the transverse direction is twice of that in the inline one.…”

Section: -Trajectories Of the Rear Circular Cylindersupporting

confidence: 89%

“…For solving the VIV case which is one of the typical fluid-structure interaction (FSI) problems, the staggered algorithm is employed. This scheme has been used for satisfactory solutions as shown in the publications [12,20,28]. Briefly, the computational steps during one time interval ∆ = − are summarized as: (a) obtain the velocities and pressure in the fluid domain by the CBS algorithm; (b) calculate the drag and lift coefficients, and , of the cylinder, and compute the cylinder motions, and , by the Newmark-type method; (c) get the updated grid movements, , using the equation; (d) return to step (a) to restart a new iteration step until the VIV behaviors become stable.…”

Section: Governing Equations and Numerical Detailsmentioning

confidence: 99%

Flow characteristics and dynamic responses of a rear circular cylinder behind the square cylinder with different side lengths

Tu¹,

Sun²,

Zhou³

et al. 2017

J. vibroeng.

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Wake-induced vibrations of a 2-DOF circular cylinder which is placed behind a stationary square cylinder with tandem arrangement are numerically investigated at low Reynolds numbers by using semi-implicit Characteristics-based split (CBS) finite element algorithm in this study. Numerical results demonstrate that the side length of the upstream square cylinder can significantly affect the characteristics of flow patterns, oscillation frequency, maximum amplitudes, -trajectories, and hydrodynamic coefficients of the rear circular cylinder. The predominant vortex shedding patterns are 2S, 2P and 2T mode. In addition to the figure "8", "raindrop" and figure "dual-8" are observed in the -vibrating trajectories for the circular cylinder. Finally, the interactions between cylinders are revealed according to the phase portrait of fluid force to displacement and the power spectral densities (PSD) features of the vibration amplitude on the rear circular cylinder and the instantaneous flow field, together with the wakeinduced vibration (WIV) mechanism underlying the oscillation characteristics of the circular cylinder behind a stationary square cylinder with different sizes.Keywords: wake-induced vibration, wake pattern, dynamic response, semi-implicit characteristic-based split finite element method.

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