Experimental Investigation of Uniform-Shear Flow Past a Circular Cylinder

Kwon, Tae Soon; Sung, Hyung Jin; Hyun, Jae Min

doi:10.1115/1.2910053

Cited by 61 publications

(67 citation statements)

References 7 publications

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“…For the square cylinder case, Ayukawa et al [9] and Hwang and Sue [10] reported positive mean lift coefficient (lift force acting from low velocity side to high velocity side), whereas Cheng et al [13,14] and Lankadasu and Vengadesan [15,16] reported negative mean lift coefficient. For the circular cylinder case, Kiya et al [18] and Kwon et al [19] reported positive mean lift coefficient whereas others reported negative mean lift coefficient. The reason for the above discrepancy among the reported mean lift coefficient is attributed to the number of parameters necessary viz, Reynolds number, blockage ratio, three-dimensionality effect, geometry and magnitude of the shear or combinations of any of these.…”

Section: Introductionmentioning

confidence: 96%

“…As a starting point, linear shear flow past a square cylinder [9][10][11][12][13][14][15][16] as well as a circular cylinder [17][18][19][20][21][22][23] has been studied. Except experimental results of Kiya et al [18] and 1116 A. LANKADASU AND S. VENGADESAN Kwon et al [19], all others reported that Strouhal number either decreases or remains constant and the mean drag coefficient decreases with increasing shear parameter. However, there is a disagreement on the direction and in the magnitude of the mean lift coefficient.…”

Section: Introductionmentioning

confidence: 99%

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Shear effect on square cylinder wake transition characteristics

Lankadasu

Vengadesan

2010

Numerical Methods in Fluids

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SUMMARYThe transition of square cylinder wake flow from two-dimensional (2-D) to three-dimensional (3-D) when inflow is subjected to linear shear is examined numerically. The value of the non-dimensional shear parameter (K ) considered in this study are 0.0, 0.1, and 0.2. The range of Reynolds number (Re) defined based on the centerline velocity and cylinder width is from Re = 150 to 700. The transition of the wake flow from 2-D laminar to 3-D is marked by streamwise vortical structures. Unlike in uniform flow, in shear flow the transition is characterized by single mode of spanwise wavelength. The critical Reynolds number (Re crit ), at which the transition from 2-D to 3-D occurs, is less in case of shear flow. The magnitude of the mean lift coefficient increases with increasing shear parameter on the positive side. The strength of the Karman vortices on the top side is higher and on the bottom side is lower when compared with the same in the uniform flow.

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Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Shear effect on square cylinder wake transition characteristics

Lankadasu

Vengadesan

2010

Numerical Methods in Fluids

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“…The case of a fixed circular cylinder placed in planar shear flow has been addressed experimentally Kwon, Sung & Hyun 1992;Sumner & Akosile 2003;Cao et al 2007) and numerically (Jordan & Fromm 1972;Yoshino & Hayashi 1984;Chew, Luo & Cheng 1997;Lei, Cheng & Kavanagh 2000;Kang 2006;Cao et al 2010). These prior studies, which mainly focused on linear shear, quantified the evolution of the vortex shedding frequency and time-averaged fluid forces as functions of the shear parameter (β), defined as the inflow velocity gradient normalized by the cylinder diameter and the oncoming flow velocity at the centre of the body.…”

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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“…Despite the high quality of many of these experimental and numerical studies, some controversial issues remain unresolved [18,13]. Kiya et al [14], Tamura et al [25], Yoshino and Hayashi [31] and Kwon et al [17] claim that the Strouhal number St D = f D/U c increases with the shear rate. On the other hand, Lei et al [18], Sumner and Akosile [24], Vitola [28] and Kang [13] state that the Strouhal number decreases with the shear.…”

Section: Introductionmentioning

confidence: 98%