Flow-induced vibration of a square cylinder without and with interference

Kumar, R. Ajith; Gowda, B. H. Lakshmana

doi:10.1016/j.jfluidstructs.2005.11.006

Cited by 37 publications

(9 citation statements)

References 31 publications

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“…This could be certainly expected to induce large scale non-linearities in the wake characteristics, particularly in the pressure distribution on the cylinder side walls, which could possibly become highly unsteady. This indicates that the cylinders could possibly experience unsteady response amplitudes somewhat similar to multiple amplitudes observed by Ajith Kumar and Gowda [17] and Wawzonek [35] (referred to in [36]) for a square section cylinder. Hence, the dependence of aerodynamic characteristics on r/B ratio need not necessarily be linear, or in other words, could possibly be non-linear in nature.…”

Section: Mode and Mechanism Of Shedding At R/b=05supporting

confidence: 72%

“…2. Considerable effort was expended to fabricate this arrangement with the design being similar to that used by Ajith Kumar and Gowda [17]. Basically, the rotary motion provided by a variable speed DC motor was converted into a translatory to-and-fro motion (in other words, oscillation) by means of a 'cam' and a 'connecting rod' mechanism ( Fig.…”

Section: Experimental Set-up and Instrumentationmentioning

confidence: 99%

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Influence of corner radius on the near wake structure of a transversely oscillating square cylinder

Kumar

Sohn

Gowda³

2009

J Mech Sci Technol

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The near wake flow field features of transversely oscillating square section cylinders with different corner radii were studied in an attempt to assess the influence of corner radius. The investigation was performed by using particle image velocimetry (PIV) technique in a water channel with a turbulence intensity of 6.5%. Five models were studied with r/B=0, 0.1, 0.2, 0.3 and 0.5 (r is the corner radius and B is the characteristic dimension of the body), and the body oscillation was limited to lock-in condition (at fe/fo=1.0; fe is the excitation frequency and fo is the vortex shedding frequency from a stationary cylinder at the same Re). The corner radius was found to significantly influence the flow features around the bodies. Except for r/B=0.5, for all the other cases of r/B ratios, cycle-to cycle variation in the mode of vortex shedding was observed in the case of oscillating cylinders inducing highly non-linear wake characteristics. Apart from variation in the shedding mode, changes in shedding cycle timing were also observed for sharp and rounded square cylinders. The hgher the r/B ratio, shedding in the near wake was found to be more uniform (lesser variation in shedding cycle timings). Another admissible shedding mechanism is newly identified to operate in the near wake of oscillating cylinders now being called as the 'passive shedding' mechanism. Results indicate that increasing the corner radius suppresses the possible instabilities of the cylinder.

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Section: Mode and Mechanism Of Shedding At R/b=05supporting

confidence: 72%

Section: Experimental Set-up and Instrumentationmentioning

confidence: 99%

Influence of corner radius on the near wake structure of a transversely oscillating square cylinder

Kumar

Sohn

Gowda³

2009

J Mech Sci Technol

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“…In the presence of an interference body, the flow pattern and the vortex shedding phenomenon from the testbody can be expected to be altered, which also influences the feedback mechanism with the result that the test-body oscillations vary for different relative positions of the test-body and the interfering body [33]. This aspect of interference effects is clearly evidenced in the present two-cylinder case as the results in Figs.…”

Section: Discussionmentioning

confidence: 59%

Multicylinder Flow-Induced Motions: Enhancement by Passive Turbulence Control at 28,000<Re<120,000

Kim

Bernitsas

Kumar

2013

Journal of Offshore Mechanics and Arctic Engineering

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The VIVACE converter was introduced at OMAE2006 as a single, smooth, circular-cylinder module. The hydrodynamics of VIVACE is being improved continuously to achieve higher density in harnessed hydrokinetic power. Intercylinder spacing and passive turbulence control (PTC) through selectively located roughness are effective tools in enhancement of flow induced motions (FIMs) under high damping for power harnessing. Single cylinders harness energy at high density even in 1 knot currents. For downstream cylinders, questions were raised on energy availability and sustainability of high-amplitude FIM. Through PTC and intercylinder spacing, strongly synergetic FIMs of 2/3/4 cylinders are achieved. Twocylinder smooth/PTC, and three/four-cylinder PTC systems are tested experimentally. Using the "PTC-to-FIM" map developed in previous work at the Marine Renewable Energy Laboratory (MRELab), PTC is applied and cylinder response is measured for inflow center-tocenter distance 2D-5D (D = diameter), transverse center-to-center distance 0. Ree[28,000], m*e[1.677-1.690], Ue[0.36-1.45 m/s], aspect ratio l/D = 10.29, and m*[, e [0.0283-0.0346]. All experiments are conducted in the low turbulence free surface water (LTFSW) channel of MRELab. Amplitude spectra and broad field-of-view (FOV) visualization help reveal complex flow structures and cylinder interference undergoing VN, interference/ proximity/wake/soft/hard galloping. FIM amplitudes of 2.2-2.8D are achieved for all cylinders in steady flow for all parameter ranges tested.

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“…Aerodynamic model tests were also conducted by using a six-beam force balance to measure the wind loads of the downwind prism in the twin-prism system. It is noted that the experimental result from Kumar and Gowda (2006) two-dimensional square cylinder indicated that the Strouhal number was 0.13. In contrast, the resulting Strouhal number in the present study of a surface-mounted square prism with a finite height (H=7D) is relatively smaller (0.094).…”

Section: Strouhal Number Of Downwind Prism In the Twin-prism Systemmentioning

confidence: 99%

“…Blazik-Borowa (2006) proposed a quasi-steady model of vibrations of two cylinders in a side-by-side arrangement. Kumar and Gowda (2006) investigated the interference effect between two neighboring twin square cylinders in a uniform flow and indicated that there was a critical combination of the gap distances that lead to maximum vibration amplitude of the upstream cylinder. Lim and Bienkiewicz (2007) studied the effect of structural coupling on the wind-induced response of twin tall building connected by a skybridge.…”

Section: Introductionmentioning

confidence: 99%

The acrosswind response of the downwind prism in a twin-prism system with a staggered arrangement

Fang¹,

Chung²,

Li³

et al. 2013

Wind and Structures

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The flow interaction between two identical neighboring twin square prisms in a staggered arrangement in an open terrain was investigated experimentally. The downwind prism was mounted on a rigid-aeroelastic setup in an open-terrain boundary layer flow to measure its acrosswind root-mean-square responses and aerodynamic damping ratios. By varying the relative location of the upwind prism and the Scruton number associated with the downwind prism, the acrosswind aeroelastic behavior of the downwind prism was analyzed and compared to that of an isolated one. Results showed that the acrosswind root-mean-square response of the downwind prism could be either suppressed or enhanced by the wake flow produced by the neighboring upwind prism. Besides the assessment of the wake effect of the downwind prism, finally, regressed relationships were presented to describe the variation of the aerodynamic damping ratio so as to predict its acrosswind fluctuating response numerically.

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Flow-induced vibration of a square cylinder without and with interference

Cited by 37 publications

References 31 publications

Influence of corner radius on the near wake structure of a transversely oscillating square cylinder

Influence of corner radius on the near wake structure of a transversely oscillating square cylinder

Multicylinder Flow-Induced Motions: Enhancement by Passive Turbulence Control at 28,000<Re<120,000

The acrosswind response of the downwind prism in a twin-prism system with a staggered arrangement

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