Influence of mass and damping ratios on VIVs of a cylinder with a downstream counterpart in cruciform arrangement

Nguyen, Tuananh; Koide, Mizuyasu; Yamada, S.; Takahashi, Tsutomu; Shirakashi, Masataka

doi:10.1016/j.jfluidstructs.2011.10.006

Cited by 17 publications

(8 citation statements)

References 19 publications

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“…Although the values of Scruton number Sc in Table 1 are nearly equal among the researches compared in Figure 2, the amplitude normalized by Sc is significantly different each other. This result confirms that the mass ratio and the damping factor influence the amplitude response independently (Nguyen et al, [8]; Mannini et al, [20]; Sun et al, [26]). [4] and the experimental studies by Ismail et al, [23] and Kawabata et al, [13]…”

Section: Vibration Behaviour Of the Isolated Square Cylindersupporting

confidence: 82%

“…In this method, other bodies are positioned downstream of the oscillating cylinder, e.g. splitter plates (Assi et al, [2]; Ali et al, [3]; Maruai et al, [4]; Dash et al, [5]), a circular cylinder (Shirakashi et al, [6]; Bae et al, [7]; Ngyuen et al, [8]; Ma et al, [9]; Chauhan et al, [10]) or a strip plate in cruciform arrangement (Koide et al, [11]; Kato et al, [12]; Kawabata et al, [13]) and fairings (Assi et al, [14]; Yu et al, [15]; Wang et al, [16]; Lou et al, [17]; Zheng and Wang [18]).…”

Section: Introductionmentioning

confidence: 99%

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Experimental Investigation of the Effect of a Downstream Square Plate on Vortex-induced Vibration and Galloping of a Square Cylinder

Mohamed¹,

Zaki²,

Shirakashi³

et al. 2020

ARFMTS

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A square cylinder exposed to a fluid flow is regarded as the simplest model of the structures in sea water or air flow, and known to show the Karman vortex induced vibration (KVIV) and the galloping in separate or overlapping ranges of flow velocity. In this study, wind tunnel experiments were performed on the cross-flow vibration of a square cylinder, and effects of a downstream square plate on the vibration were investigated to develop a convenient passive technique for vibration control. The square plate has a side length w equal to the side length of the square cylinder D (= 26 mm) and set downstream with the gap ratio S/D in the range of 0.12 to 2.90 where S is the separation gap. The results show that the square plate has only little influence on KVIV and enhances the galloping, resulting in the lower critical reduced velocity of galloping Ug i.e. the onset velocity of galloping reduced to about half of the isolated counterpart at S/D = 0.98. Most remarkable effect of the downstream square plate is the enhancement of the vibration near the peak velocity of KVIV at S/D = 1.17, which is around five times larger as compared with the isolated counterpart. This may indicate occurrence of the wake-body-interference fluid elastic vibration.

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Section: Vibration Behaviour Of the Isolated Square Cylindersupporting

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of the Effect of a Downstream Square Plate on Vortex-induced Vibration and Galloping of a Square Cylinder

Mohamed¹,

Zaki²,

Shirakashi³

et al. 2020

ARFMTS

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show abstract

“…The effects of the mass ratio (Prasanth, Premchandran & Mittal 2011), the structural damping coefficient (Nguyen et al 2012) and the Reynolds number (Govardhan & Williamson 2006) on the lock-in regime have also been extensively studied. However, the study on the induced mechanisms of frequency lock-in has not been thorough.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of frequency lock-in in vortex-induced vibrations at low Reynolds numbers

Zhang

et al. 2015

J. Fluid Mech.

179

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In this study, a CFD-based linear dynamics model combined with the direct Computational Fluid Dynamics/Computational Structural Dynamics (CFD/CSD) simulation method is utilized to study the physical mechanisms underlying frequency lock-in in vortex-induced vibrations (VIVs). An identification method is employed to construct the reduced-order models (ROMs) of unsteady aerodynamics for the incompressible flow past a vibrating cylinder at low Reynolds numbers (Re). Reduced-order-model-based fluid-structure interaction models for VIV are also constructed by coupling ROMs and structural motion equations. The effects of the natural frequency of the cylinder, mass ratio and structural damping coefficient on the dynamics of the coupled system at Re = 60 are investigated. The results show that the frequency lock-in phenomenon at low Reynolds numbers can be divided into two patterns according to different induced mechanisms. The two patterns are 'resonance-induced lock-in' and 'flutter-induced lock-in'. When the natural frequency of the cylinder is in the vicinity of the eigenfrequency of the uncoupled wake mode (WM), only the WM is unstable. The dynamics of the coupled system is dominated by resonance. Meanwhile, for relatively high natural frequencies (i.e. greater than the eigenfrequency of the uncoupled WM), the structure mode becomes unstable, and the coupling between the two unstable modes eventually leads to flutter. Flutter is the root cause of frequency lock-in and the higher vibration amplitude of the cylinder than that of the resonance region. This result provides evidence for the finding of De Langre (J. Fluids Struct., vol. 22, 2006, pp. 783-791) that frequency lock-in is caused by coupled-mode flutter. The linear model exactly predicts the onset reduced velocity of frequency lock-in compared with that of direct numerical simulations. In addition, the transition frequency predicted by the linear model is in close coincidence with the amplitude of the lift coefficient of a fixed cylinder for high mass ratios. Therefore, it confirms that linear models can capture a significant part of the inherent physics of the frequency lock-in phenomenon.

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“…Vortex-induced vibration (VIV) of a circular cylinder has always been of interest to researchers due to its engineering applications (Jauvtis & Williamson 2003;Zhao et al 2009). In particular, if the self-oscillation frequency of a downstream structure is close to the vortex shedding frequency from the upstream circular cylinder, the structure will be destroyed by resonance (Deng et al 2007;Kato et al 2012;Nguyen et al 2012). Therefore, the relationship between wake morphologies and flow frequencies is worth studying.…”

Section: Introductionmentioning

confidence: 99%

Spectral Analysis of Flow Around Single and Two Crossing Circular Cylinders Arranged at 60 and 90 Degrees

Wang¹,

Yang²,

Tang³

et al. 2022

Preprint

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Two modal decomposition techniques, including proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD), are used to identify the wake patterns past single and two crossing cylinders in 60° and 90° arrangements with gap ratio G = 4. The flow is simulated using direct numerical simulations (DNS) for Reynolds numbers Re = 100. The spatial scale of flow decreases with increasing modal frequency from the modal analysis. Two main modes are identified in the wake of the cylinders, namely spatially antisymmetric and symmetric modes. Antisymmetric and symmetric modes are related to cylinders’ vortex shedding and shedding vortices’ shift motion, respectively, whose frequencies are odd and even multiples of cylinders’ lift force frequency. In addition, a low-frequency mode concerning the shadowing effect of the downstream cylinder (DC) in 90° arrangement is found in the wake of the DC centre.

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Influence of mass and damping ratios on VIVs of a cylinder with a downstream counterpart in cruciform arrangement

Cited by 17 publications

References 19 publications

Experimental Investigation of the Effect of a Downstream Square Plate on Vortex-induced Vibration and Galloping of a Square Cylinder

Experimental Investigation of the Effect of a Downstream Square Plate on Vortex-induced Vibration and Galloping of a Square Cylinder

Mechanism of frequency lock-in in vortex-induced vibrations at low Reynolds numbers

Spectral Analysis of Flow Around Single and Two Crossing Circular Cylinders Arranged at 60 and 90 Degrees

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