Vortex shedding and aerodynamic forces on a circular cylinder in linear shear flow at subcritical Reynolds number

Cao, Shuyang; Ozono, Shigehira; Hirano, Kimitaka; Tamura, Yukio

doi:10.1016/j.jfluidstructs.2006.11.004

Cited by 29 publications

(33 citation statements)

References 17 publications

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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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Section: Introductionmentioning

confidence: 99%

Vortex-induced vibrations of a cylinder in planar shear flow

2017

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“…In order to relate the data to the wake width scaling one would need λ and b of the previous works, but they were not available. On the other hand, most previous works did present C D [13,28,24,18,17,31,3], which can be used convert the results to a scaling proportional to the wake scaling. The converted results showed a substantial collapse and shed light onto the controversy.…”

Section: The Controversymentioning

confidence: 99%

“…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. According to Cao et al [3], the Strouhal number does not vary with shear at all. This state of affairs is clearly shown in Fig.…”

Section: Introductionmentioning

confidence: 95%

“…The different regimes appearing as Re D increases, discussed above for unsheared wake flow, are not documented in detail for the sheared case, but there is no reason to consider a priori that overall the two-dimensional pattern of vortex formation would not prevail. Many contributions to the controversy were produced from experiments [14,17,24,3] or numerical simulations [12,31,18,28,13].…”

Section: Introductionmentioning

confidence: 99%

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On the controversy regarding the effect of flow shear on the Strouhal number of cylinder vortex shedding

Gennaro

Colaciti

Medeiros

2013

Aerospace Science and Technology

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“…Kwon et al [3] arrived at the same conclusions on the basis of their experiments. More recently, however, Sumner and Akosile [4] and Cao et al [5,6] reported that the Strouhal number remained unchanged as the shear rate increased at sub-critical Reynolds numbers. Lei et al [7] performed two-dimensional simulations with shear rates up to K = 0.25 for Reynolds numbers ranging from 80 to 1000.…”

Section: Introductionmentioning

confidence: 98%