A novel drag reduction and vortex shedding mitigation measure for a circular cylinder in the subcritical regime

Ma, Wenyong; Du, Zhan; Zhang, Xiaobin; Liu, Qingkuan; Liu, Xiaobing

doi:10.1088/1873-7005/abd3ac

Cited by 3 publications

(6 citation statements)

References 46 publications

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“…Consequently, the communication between detached shear flow on both sides is interrupted and vortex induced fluctuation is suppressed. The amplitude of an elastically supported cylinder can be effectively and significantly reduced by the C-ring, as reported by Ma et al (2021). This is consistent with the results obtained herein, wherein a small lift fluctuation results in small vibrations.…”

Section: Resultssupporting

confidence: 92%

“…The radius and arc length of the C-ring have a significant influence on the flow field and aerodynamic performance of the cylinder (Ma et al, 2021). To investigate the influence of C-rings with different radii and arc lengths on the cylinder, various radii (represented by R ) and arc lengths (represented by θ ) were simulated herein as listed in Table 1.…”

Section: Numerical Setupmentioning

confidence: 99%

“…; (III) wake controller preventing interaction of entrainment layers, such as streamer, fairing, splitter plates, guide wing, slit, etc. It should be noted that the helical line, fairing and splitter plate have good vibration suppression effects so as to be widely used in engineering practices.

Figure 1.Passive measures on VIV suppression (from Ma et al (2021)). …”

Section: Introductionmentioning

confidence: 99%

“…Unfortunately, installing these mitigating measures is expensive and the related workload is considerable. To address this problem, Ma et al (2021) recently proposed a novel cost-effective mitigating measure using a C-ring, which exhibits good vibration suppression. Depending on the limited test data and experiences, Ma et al (2021) thought that the negative pressure on leeward side of the cylinder could be reduced by the air concentrated in the chamber of the C-ring.…”

Section: Introductionmentioning

confidence: 99%

“…To address this problem, Ma et al (2021) recently proposed a novel cost-effective mitigating measure using a C-ring, which exhibits good vibration suppression. Depending on the limited test data and experiences, Ma et al (2021) thought that the negative pressure on leeward side of the cylinder could be reduced by the air concentrated in the chamber of the C-ring. At the same time, the concentrated air squeezed by oncoming flow had to flow along spanwise direction behind the cylinder, which resulting in longer recirculation zone, smaller influencing area and strength of alternative vortex shedding acting on the cylinder.…”

Section: Introductionmentioning

confidence: 99%

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Numerical study on aerodynamic characteristics and flow field of a circular cylinder equipped with a C-ring behind at Re = 1000

Jing

Zhang

2023

Advances in Structural Engineering

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Slender cylindrical structures such as cables and signal poles often experience vortex-induced vibrations. Recently, scholars have developed a novel mitigating measure by equipping a C-ring on the structures, where the C-ring is always behind the cylinder by tail rudder, but the mitigation mechanism is still unclear. To this end, the OpenFOAM©, an open source software, has been adopted in this study to carry out the large-eddy simulations (LES) to investigate the influence of a C-ring on the aerodynamic forces, surface pressure, and flow around a circular cylinder at Re = 1000, where the dynamic k-equation LES model is employed. Although the Re is far smaller than that in the reality, the aerodynamic characteristics and flow is also representative and worth studying in this subcritical range. Furthermore, to determine the appropriate radii ( R) and arc lengths ( θ) of the C-ring, various values of R (0.7 D, 0.8 D, 0.9 D, and 1.0 D, where D is diameter of the cylinder) and θ (60°, 90°, 120°, 150°, and 180°) are considered and studied herein. The results indicate that a C-ring can reduce the SD of the lift coefficient by 40%–90% compared to that of a bare cylinder, whereas it has an unremarkable effect on the mean drag coefficient. The C-ring also has a significant influence on the fluctuating pressure coefficients, resulting in a small SD of the fluctuating lift. The spanwise flow on the leeward side of the cylinder under the influence of C-rings with different radii and arc lengths can be categorized into three modes. Meanwhile, the C-ring mitigates wind-induced vibrations by enhancing the spanwise flow on the leeward side of the cylinder. Finally, the appropriate parameters for the C-ring are recommended as follows: R = 0.7 D and θ = 180°; R = 0.8 D and θ = 150°; R = 0.9 D and θ = 150°; R = 1.0 D and θ = 120°, 150°.

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Section: Resultssupporting

confidence: 92%

Section: Numerical Setupmentioning

confidence: 99%

Figure 1.Passive measures on VIV suppression (from Ma et al (2021)). …”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Numerical study on aerodynamic characteristics and flow field of a circular cylinder equipped with a C-ring behind at Re = 1000

Jing

Zhang

2023

Advances in Structural Engineering

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Experimental and numerical investigation on the wake flow and vortex shedding of a rotating circular cylinder

Liu

Jin

et al. 2023

Physics of Fluids

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When fluid passes through a still cylinder, alternate shedding vortices are formed on the two sides of the cylinder in the wake. Regarding a rotating circular cylinder, the rotation can affect the wake flow and vortex shedding pattern. To investigate the wake flow and surface pressure characteristics of a rotating cylinder at different rotational speeds, wind tunnel tests and numerical simulation methods through Fluent were used. The dimensionless rotational speed was discussed for its impact on the vortex shedding intensity and pattern. Additionally, the correlation between the cylinder surface wind pressure and the vortex shedding pattern was analyzed. The results of this study provide useful insights into the mechanisms underlying the vortex shedding phenomenon and the effects of rotational speed on the wake flow and surface pressure of a rotating cylinder. The results show that an increase in the dimensionless rotational speed will change the characteristics of the wind pressure distribution, leading to the variation in aerodynamic coefficients. On the other hand, the vortex shedding characteristics of the wake flow will also be affected, with changes in the vortex shedding pattern and direction, thereby changing the characteristics of the wake deviation angle and correlation. Based on the analysis of wake flow speed power spectrum characteristics and the Reynolds number effect, the mechanism of the vortex shedding change caused by flow transitions is speculated and verified by numerical simulation of the vorticity field.

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Reduction of Total Drag for Finite Cylinders in Turbulent Flow With a Half-C Shape Upstream Body

Islam

Shoshe

Ahmed

2023

Inter J Fluid Mech Res

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The effect of an upstream half-C shape body on the reduction of the total drag of a finite circular cylinder is investigated experimentally. Five main cylinders, each with an upstream half-C shape body placed at five upstream positions, a total of 25 different configurations, are considered during the experimentation at a Reynolds number in the range of 1.2 × 104 to 1.6 × 105. The aspect ratios of the main cylinders are 1.25, 2.09, 3.03, 3.78, and 4.90 and the upstream bodies are taken as 90° peripheral cut-outs of the respective main cylinder. The total configuration drag coefficient is calculated from the time-averaged drag force on the configuration and compared with the drag coefficient of the respective main cylinder. Results suggest that at least 20% of the total drag of the configuration might be reduced with the upstream half-C shape body, and the reduction varies with the main cylinders' aspect ratio and the upstream body placement distance. The maximum drag reduction is about 55% if the half-C shape body is placed at an upstream distance of 66% of the main cylinder diameter with an aspect ratio of 3.03 and at a Reynolds number of 1.8 × 104. A critical distance ratio is found beyond which drag cannot be reduced by the upstream half-C shape body, and the attribution might be given to a formation of intermittent swirling flow in the cavity mode.

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A novel drag reduction and vortex shedding mitigation measure for a circular cylinder in the subcritical regime

Cited by 3 publications

References 46 publications

Numerical study on aerodynamic characteristics and flow field of a circular cylinder equipped with a C-ring behind at Re = 1000

Numerical study on aerodynamic characteristics and flow field of a circular cylinder equipped with a C-ring behind at Re = 1000

Experimental and numerical investigation on the wake flow and vortex shedding of a rotating circular cylinder

Reduction of Total Drag for Finite Cylinders in Turbulent Flow With a Half-C Shape Upstream Body

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