The interaction between flow-induced vibration mechanisms of a square cylinder with varying angles of attack

Nemes, András; Zhao, Jisheng; Jacono, David Lo; Sheridan, John

doi:10.1017/jfm.2012.353

Cited by 186 publications

(153 citation statements)

References 42 publications

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“…Structural stiffness of the oscillating system was controlled by stainless-steel extension springs attached to both sides of the support carriage and the base of the air-bearing system. More details of this hydroelastic system can be found in Nemes et al (2012) and Zhao et al (2014a,b).…”

Section: Experimental Methodologymentioning

confidence: 99%

“…VIV and galloping need not occur mutually exclusively; their occurrence depends on the flow and structural properties. In fact, the two FIV phenomena may occur in the same flow regimes, as shown in Corless & Parkinson (1988), Nemes et al (2012) and Zhao et al (2014b). Nemes et al (2012) and Zhao et al (2014b) have shown that large amplitude response regions can result from the interaction between VIV and galloping.…”

mentioning

confidence: 92%

“…galloping), it should be noted that VIV can still occur under certain conditions (e.g. mass and damping ratios) and dominate over a range of reduced velocity when the axial symmetry is broken, as demonstrated by Corless & Parkinson (1988), Nemes et al (2012) and Zhao et al (2014b). In such cases, however, the body may also be subjected to transverse galloping.…”

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confidence: 99%

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Experimental investigation of flow-induced vibration of a rotating circular cylinder

et al. 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 : 18605 While flow-induced vibration of bluff bodies has been extensively studied over the last half-century, only limited attention has been given to flow-induced vibration of elastically mounted rotating cylinders. Since recent low-Reynolds-number numerical work suggests that rotation can enhance or suppress the natural oscillatory response, the former could find applications in energy harvesting and the latter in vibration control. The present experimental investigation characterises the dynamic response and wake structure of a rotating circular cylinder undergoing vortex-induced vibration at a low mass ratio (m * = 5.78) over the reduced velocity range leading to strong oscillations. The experiments were conducted in a free-surface water channel with the cylinder vertically mounted and attached to a motor that provided constant rotation. Springs and an air-bearing system allow the cylinder to undertake low-damped transverse oscillations. Under cylinder rotation, the normalised frequency response was found to be comparable to that of a freely vibrating non-rotating cylinder. At reduced velocities consistent with the upper branch of a non-rotating transversely oscillating cylinder, the maximum oscillation amplitude increased with non-dimensional rotation rate up to α ≈ 2. Beyond this, there was a sharp decrease in amplitude. Notably, this critical value corresponds approximately to the rotation rate at which vortex shedding ceases for a non-oscillating rotating cylinder. Remarkably, at α = 2 there was approximately an 80 % increase in the peak amplitude response compared to that of a non-rotating cylinder. The observed amplitude response measured over the Reynolds-number range of (1100 Re 6300) is significantly different from numerical predictions and other experimental results recorded at significantly lower Reynolds numbers.

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Section: Experimental Methodologymentioning

confidence: 99%

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confidence: 92%

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Experimental investigation of flow-induced vibration of a rotating circular cylinder

et al. 2017

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“…Previous studies have emphasized the impact of breaking the system symmetry, for example by forcing the circular body to rotate about its axis (Bourguet & Lo Jacono 2014), by placing it close to a side wall (Zhao & Cheng 2011) or by considering a non-circular cross-section (Nemes et al 2012). Typical effects of such symmetry breaking are the emergence of asymmetric wake patterns, the appearance of a time-averaged cross-flow force and the change of frequency ratio between the in-line and cross-flow forces and body oscillations.…”

Section: Introductionmentioning

confidence: 99%

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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“…Previous studies have greatly enhanced our understanding of flow past a single cylinder both numerically and experimentally (Luo et al 1994;Williamson 1996;Zdravkovich 1997;Williamson and Govardhan 2004;Alonso et al 2009;Yoon et al 2010;Bao et al 2011;Nemes et al 2012). As confirmed in these works, some parameters, such as material properties of the cylinder, cross-section shape, flow incidence angle, and Reynolds number, can lead to significant changes in flow field, as well as flow-induced forces and vibrations of the cylinder.…”

Section: Introductionmentioning

confidence: 85%

Numerical Study of Flow Past Two Transversely Oscillating Triangular Cylinders in Tandem at Low Reynolds Number

Zhai

Wang

2017

JAFM

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Flow past two tandem triangular cylinders forced to oscillate transversely in a uniform flow, is numerically investigated at a Reynolds number Re = 100. The incompressible Navier-Stokes equations in ArbitraryLagrangian-Eulerian formulation are solved by four-step fractional finite element method. The two cylinders are oscillated in phase and their motions are limited to low amplitudes with a wide frequency range. This study focuses on two typical spacings between the two cylinders, corresponding to vortex suppression (VS) regime and vortex formation (VF) regime respectively for flow past two stationary cylinders. Numerical results show that the response characteristics of two cylinders are significantly affected by the spacing, oscillation amplitude and frequency. For the VS spacing, both cylinders have a wider lock-on region, especially at relatively larger amplitude and higher frequency; the downstream wake patterns are mainly 2S and a combination of 2S* and 2S. However, for the VF spacing, the lock-on frequency range of the cylinders is even slightly narrower than that of a single oscillating cylinder; the wake field is more complex since it may comprises 2S, P+S and 2S* structures at some higher frequencies. Additionally, the hydrodynamic forces are also discussed in terms of mean and root mean square quantities, and reveal large differences between oscillating and stationary cylinders.

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The interaction between flow-induced vibration mechanisms of a square cylinder with varying angles of attack

Cited by 186 publications

References 42 publications

Experimental investigation of flow-induced vibration of a rotating circular cylinder

Experimental investigation of flow-induced vibration of a rotating circular cylinder

Vortex-induced vibrations of a cylinder in planar shear flow

Numerical Study of Flow Past Two Transversely Oscillating Triangular Cylinders in Tandem at Low Reynolds Number

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