Vorticity measurements in the near wake of a circular cylinder at low Reynolds numbers

Green, R. B.; Gerrard, J. H.

doi:10.1017/s002211209300031x

Cited by 80 publications

(48 citation statements)

References 10 publications

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“…The results are therefore complementary to the ones published by Green and Gerrard (1993) who explained the vortex shedding process for Ri D ¼ 0. In the second part of the result section, the flow close around the cylinder will be discussed.…”

Section: Resultssupporting

confidence: 83%

Near-wake effects of a heat input on the vortex-shedding mechanism

Kieft

Rindt

Steenhoven

2007

International Journal of Heat and Fluid Flow

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Section: Resultssupporting

confidence: 83%

Near-wake effects of a heat input on the vortex-shedding mechanism

Kieft

Rindt

Steenhoven

2007

International Journal of Heat and Fluid Flow

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“…In the higher-Re regime (Re = 400-600) the shed-vortex cores rapidly cross the centeraxis. The change observed here in the near-wake behaviour is similar to that described by Green and Gerrard (1993) for the circular cylinder in the fully established regime. It has been shown to be linked with the evolution of the shear-stress field.…”

Section: Wake-flow Structure In the Mid-cross Planesupporting

confidence: 87%

Particulars of the cross- and spanwise near-wake development of a short Semicircular-section Shell, through the TransitionRe-range (60 ≤Re ≤ 600)

Coutanceau

Migeon

Ehrmann

2000

J Vis

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Within the fundamental context of quasi-2D bluff-body near-wake investigation, we analyse the way the initial wake vortices (primary and secondary vortices) form and develop with time behind a short (5.2:1) cylindrical semicircular shell (hollow at the back), after an impulsive start in translation. The study includes the transition regime and non-usual cross-sectional shapes. The structure of the vortices is examined by means of precise visualizations both in the mid-cross and mid-span planes. The particulars induced by the hollow face are deduced from a comparison with the cases of analogous solid cylinders and more particularly with the full semicircular cylinder (Boisaubert et al., 1996; Coutanceau et aI.,1998).The crosswise analysis shows that, except some fundamental difference at the separation initiation and some differences in details, a similar development ofthe Benard-Karman-vortices is observed, thus:-the regime ofthe occurring structures changes beyond the first phase of development (i.e. t"~6) when Reynolds number is passing through a critical value Re, (here 120 :s; Re, :s; 140)-Kelvin-Hehnholtz instabilities are detected for Re = 600 in the rolled-up separated shear layers originating from the sharp body-edges. On the contrary, the spanwise analysis reveals that the hollow face plays an important role in the time-development of the induced body-end three-dimensionalities (end-vortices and opposite spanwise currents) and intrinsic three-dimensionalities respectively. Thus, as opposed to solid bodies similarly limited in span, the emergence of clear patterns of secondary Taylor-Gortler-like vortices in the near wake have been experimentally proved for the first time when Re passes beyond the transition value of Re, '" 200. The consequence on the global structure of the flow is deduced.

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“…A lot of effort was made to explain the physics of circular cylinder wake dynamics. [1][2][3] They showed that vortex shedding for low Reynolds numbers can be characterized by vortex splitting and high shear stress occurring in the near-wake. Unal and Rockwell 4 investigated the near wake vortex formation from the context of absolute instability and showed that the shear layer separating from the cylinder shows an exponential variation of fluctuating kinetic energy with distance downstream of the cylinder.…”

Section: Introductionmentioning

confidence: 99%

Energy contents and vortex dynamics in Mode-C transition of wired-cylinder wake

2013

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The 3D transition of the flow behind a circular cylinder with a near-wake wire disturbance has been investigated experimentally. The flow is oriented horizontally and the wire is positioned in the upper half of the wake. We performed flow visualization and particle image velocimetry experiments to investigate the influence of the wire on various properties of the flow, such as the dynamics of the spanwise structures. Experiments were performed in the Reynolds number range of Re = 165–300. It is shown that in Mode-C transition of the wired cylinder wake, some part of the streamwise vorticity content of the upper von Kármán vortices located at the perturbed side, is transferred to the secondary vortices. This vorticity transfer results in upper von Kármán vortices which are weaker than the lower ones. The analysis of the discrete energy content of the wake supports this analysis by showing that the energy intensity at von Kármán vortex shedding frequency f0 at the perturbed side of the wake is less than the energy intensity in the lower half. This leads to conclusion that the excess energy is transferred to the subharmonic frequency f1 ≈ f0/2.

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Vorticity measurements in the near wake of a circular cylinder at low Reynolds numbers

Cited by 80 publications

References 10 publications

Near-wake effects of a heat input on the vortex-shedding mechanism

Near-wake effects of a heat input on the vortex-shedding mechanism

Particulars of the cross- and spanwise near-wake development of a short Semicircular-section Shell, through the TransitionRe-range (60 ≤Re ≤ 600)

Energy contents and vortex dynamics in Mode-C transition of wired-cylinder wake

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