Vortex shedding suppression and wake control: A review

Rashidi, Saman; Hayatdavoodi, Masoud; Esfahani, Javad Abolfazli

doi:10.1016/j.oceaneng.2016.08.031

Cited by 232 publications

(56 citation statements)

References 164 publications

(62 reference statements)

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“…The passive methods depend on modifications of the bluff body geometry, which affect the formation of the vortex shedding. The active control methods need external energy to affect the fluid flow [11,33].…”

Section: Introductionmentioning

confidence: 99%

Numerical experiments of the flow around a bluff body with and without roughness model near a moving wall

Pereira

Oliveira

Moraes

et al. 2020

J Braz. Soc. Mech. Sci. Eng.

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Numerical tests at high Reynolds number flows were taken on circular cylinder placed near and parallel to a moving ground. A moving ground running at the same speed as the free stream eliminates the confusing effects of the boundary layer formed on the ground being, therefore, more effective to establish a better understanding of the relationship between complete vortex shedding suppression and surface roughness. A detailed quantitative measurement of the flow field around the cylinder using Lagrangian vortex method with roughness model was carried out. The effect of higher surface roughness heights is studied because it introduces greater instabilities in the boundary layer of bluff bodies. The purpose is to investigate supercritical flow patterns from subcritical Reynolds number flow simulations. The present results are compared against those measured for smooth cylinder under the same flow conditions. It is found that certain critical gap ratio between the rougher cylinder bottom and the moving wall significantly reduces the drag force. The lift force points away from the wall plane. The full vortex shedding suppression is successfully anticipated. In addition, the Strouhal number vanishes. The contribution of this research is to report that von Kámán-type vortex shedding totally ceases and instead two nearly parallel shear layers are formed behind the cylinder in moving ground when employing two-dimensional modeling of roughness. Previous numerical results for flow around smooth cylinder placed closer to the moving ground did not capture the behavior of Strouhal number equal to zero. Unfortunately, there is a lack of experimental results for rough cylinder near a moving wall, which motives the present study.

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Section: Introductionmentioning

confidence: 99%

Numerical experiments of the flow around a bluff body with and without roughness model near a moving wall

Pereira

Oliveira

Moraes

et al. 2020

J Braz. Soc. Mech. Sci. Eng.

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show abstract

“…In these cases, the structure experiences unsteady loading due to flow separation and formation of the vortices and the wake region. There are several approaches to reduce VIV, see, e.g., Rashidi et al (2016).…”

Section: Ballast-stabilised Platformsmentioning

confidence: 99%

On motion analysis and elastic response of floating offshore wind turbines

Lamei

Hayatdavoodi

2020

J. Ocean Eng. Mar. Energy

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Wind energy industry is expanded to offshore and deep water sites, primarily due to the stronger and more consistent wind fields. Floating offshore wind turbine (FOWT) concepts involve new engineering and scientific challenges. A combination of waves, current, and wind loads impact the structures. Often under extreme cases, and sometimes in operational conditions, magnitudes of these loads are comparable with each other. The loads and responses may be large, and simultaneous consideration of the combined environmental loads on the response of the structure is essential. Moreover, FOWTs are often large structures and the load frequencies are comparable to the structural frequencies. This requires a fluid-structure-fluid elastic analysis which adds to the complexity of the problem. Here, we present a critical review of the existing approaches that are used to (i) estimate the hydrodynamic and aerodynamic loads on FOWTs, and (ii) to determine the structures' motion and elastic responses due to the combined loads. Particular attention is given to the coupling of the loads and responses, assumptions made under each of the existing solution approaches, their limitations, and restrictions, where possible, suggestions are provided on areas where further studies are required.

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“…Dhinakaran and Ponmozhi [ 8 ] found that compared to that for a solid cylinder, a considerable heat transfer increment was achieved for a permeable cylinder, since more fluid passed through the porous cylinder, carrying more heat away. Besides, a porous medium provides an ability of controlling the flow characteristics and suppressing the formation of vortex shedding [ 9 ]. For example, Al-Sumaily and Thompson [ 10 ] found that for pulsatile flow over a circular cylinder in a channel with the presence of the porous media, a highly stable flow occurs without the formation of the extended wake in the flow field.…”

Section: Introductionmentioning

confidence: 99%

Effect of Prandtl Number on Mixed Convective Heat Transfer from a Porous Cylinder in the Steady Flow Regime

Tang

2020

Entropy

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The effect of the Prandtl number (Pr) on the flow and heat transfer from a porous circular cylinder with internal heat generation in the mixed convection regime is numerically investigated. The steady flow regime is considered over the ranges of the Reynolds number (Re), Darcy number (Da), and Richardson number (Ri), varying from 5 to 40, 10−6 to 10−2, and 0 to 2, respectively. The wake structure, the temperature distribution, and the heat transfer rate are discussed. Besides precipitating the growth of the recirculating wake, the Prandtl number is found to have a significant impact on the thermal characteristics. The concave isotherms, resembling a saddle-shaped structure, occur behind the cylinder at larger Pr, resulting in swells of the isotherms pairing off at the lateral sides. These swells are found to have a negative effect on heat transfer owing to a relatively smaller temperature gradient there. Then, the heat transfer rate in terms of the local Nusselt number (Nu) and enhancement ratio (Er) is calculated, which is closely related to Pr, Re, Da, and Ri. The local minimum heat transfer rate along the cylinder surface is found at the position where the swells of the isotherms form.

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Vortex shedding suppression and wake control: A review

Cited by 232 publications

References 164 publications

Numerical experiments of the flow around a bluff body with and without roughness model near a moving wall

Numerical experiments of the flow around a bluff body with and without roughness model near a moving wall

On motion analysis and elastic response of floating offshore wind turbines

Effect of Prandtl Number on Mixed Convective Heat Transfer from a Porous Cylinder in the Steady Flow Regime

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