Features of the turbulent flow around symmetric elongated bluff bodies

Taylor, Zachary; Palombi, Emanuela; Gurka, Roi; Kopp, Gregory A.

doi:10.1016/j.jfluidstructs.2010.10.004

Cited by 58 publications

(20 citation statements)

References 47 publications

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“…For readability, only spectra of the ATT wakes at θ/θ 0 of 2.3 and 3.1 were shown. For the ST wake, the vortex shedding frequency, f v , was evidenced by the large peak observed at a frequency of about 355 Hz corresponding to a von Kármán Strouhal number, St v = f v h/Ū ∞ , of 0.24 in close agreement with the values reported in [20]. Higher frequency peaks observed in the energy spectrum of the ST wake correspond to the subharmonics of the vortex shedding frequency, f v , typical of a turbulent wake flow.…”

Section: Spectral Analysissupporting

confidence: 86%

Development of Turbulent Wakes Evolving from Asymmetric Shear Layers

Dghim

Momayez

Ferchichi

et al. 2017

Heat Transfer Engineering

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This paper reports an experimental investigation on the response of a turbulent wake past an elongated flat plate to various upstream flow conditions. Different tripping wires were placed on the upper side of the plate downstream the leading edge resulting in asymmetric shear layers evolving from the trailing edges. Mean flow and turbulent fields of the asymmetric wakes were compared to their symmetrical counterpart. The symmetrical wake was found to attain a self-similar state whereas asymmetric wakes continued to slowly evolve towards an expected asymptotic behaviour at a rate that strongly depends on the imposed initial conditions.

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Section: Spectral Analysissupporting

confidence: 86%

Development of Turbulent Wakes Evolving from Asymmetric Shear Layers

Dghim

Momayez

Ferchichi

et al. 2017

Heat Transfer Engineering

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“…The location of reattachment point was estimated using the data from other researches. A detailed particle image velocimetry (PIV) testing of an elongated bluff body with a similar triangular leading edge and chord-to-thickness ratio (Taylor et al, 2011) showed the leading-edge reattachment length is around 2.1 times of thickness (2.1 ± 0.06 H ) under smooth flow. For an infinite plate with a triangular leading edge, Djilali and Gartshore (1992) reported a reattachment length of 2.4 H. Meanwhile, the reattachment lengths are dependent on the turbulence parameters (e.g.…”

Section: Major Resultsmentioning

confidence: 99%

“…As a comparison, the St number of a thin plate (chord-to-thickness ratio 33.3) is 0.156, and 0.20 for a flat plate with round corners (Simiu and Scanlan, 1996). The St number of an elongated plate with a chord-to-thickness ratio 7.0 is 0.19 (Taylor et al, 2011). The periodic vortex shedding in the wake of both decks can cause the enhancement of force coherence and make the decay curves irregular.…”

Section: Major Resultsmentioning

confidence: 99%

Span-wise coherence of fluctuating forces on twin bridge decks and the turbulence effect

Xia

2019

Advances in Structural Engineering

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Unlike the adequate researches on a single-box girder, the understanding of span-wise force correlation on twin decks is limited. A sectional model pressure testing of a widely slotted twin-box girder has been carried out in the background of a 5000-m-long bridge. Three grid configurations separated the effect of turbulence intensity and integral scale. Seven test sections were set on the model with totally 532 pressure taps. After the correction of pressure distortion, the correlation coefficients and integral scales of forces were compared on the leeward and the windward decks. Root coherence of lift was analyzed in detail at several separation distances. Pressure signals were used to explain why force coherence is stronger than flow and why “low frequency curve” phenomenon occurs. Considering the shortage of existing expressions, a simple but efficient form was proposed which can fit the coherence on the leeward, the windward, and the whole decks. The parameters in different flows can be reconstructed by linear functions which benefits new model’s application. In the final, the influences of turbulence intensity and integral scale on force coherence were illustrated.

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“…The phase-averaging method is extremely useful when the flow fields have the periodic feature because non-periodic phase such as random signals can be removed (Ozgoren, 2006;Taylor et al, 2011). In this study, to compare the features of three vortex shedding wakes, the phase-averaging streamlines of the (x, y)-plane are constructed from the PIV velocity data based on the vortex shedding frequency calculated by the FFT analysis.…”

Section: Phase-averaging Vortical Structurementioning

confidence: 99%

Wavelet multi-resolution analysis on wake flows behind three-dimensional bluff bodies

Fujimoto

Rinoshika

2015

JFST

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In order to improve the aerodynamic performance of external side mirror of race car, the wake flow around three-dimensional bluff body is studied in this study. Firstly, the high-speed PIV was applied to measure turbulent wakes generated by asymmetric side mirror (called CT-cylinder) and semi-cylinder at a Reynolds number of 6,240 in the circulating water channel. These flow fields were evaluated by time-averaged, instantaneous and phase-averaged flow structures and the FFT analysis. And then, one-and two-dimensional wavelet multi-resolution techniques were used to analyze the instantaneous velocity and vorticity data in order to obtain the turbulent structures of various scales. It is found that the CT-cylinder generates smaller separation region and lower Reynolds shear stresses than that of semi-cylinder, and produces the asymmetric flow structure and aerodynamic downforce. In the wake of CT-cylinder, the size or shape of the vortices shed from upper and lower side is different and the vorticity of upper side is larger than that of lower side, causing asymmetry and high-intensity vertical velocity fluctuation. The most contribution to the Reynolds shear stress come from large-scale structures and account about 82.0 % for CT-cylinder wakes and 78.6 % for semi-cylinder wake. The relatively small-scale structures make less contribution to Reynolds shear stresses.

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Features of the turbulent flow around symmetric elongated bluff bodies

Cited by 58 publications

References 47 publications

Development of Turbulent Wakes Evolving from Asymmetric Shear Layers

Development of Turbulent Wakes Evolving from Asymmetric Shear Layers

Span-wise coherence of fluctuating forces on twin bridge decks and the turbulence effect

Wavelet multi-resolution analysis on wake flows behind three-dimensional bluff bodies

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