The Reynolds number dependency of the steady and unsteady loading on a slightly rough circular cylinder: From subcritical up to high transcritical flow state

Hinsberg, Nils Paul van

doi:10.1016/j.jfluidstructs.2015.04.002

Cited by 40 publications

(29 citation statements)

References 28 publications

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“…The Section 4 will summarize the key findings of this study. The rough circular cylinder aerodynamics has been reasonably reported in the literature [2,9,11,12,14,16,18], however, very little attention has been paid to the problem of the flow around the rough cylinder near a moving wall [10]. In recent past works [10,11], it has been reported that the effect of two-dimensional roughness model is much more sensitive than single turbulence modeling.…”

Section: Physical Modelingmentioning

confidence: 99%

“…In the context of the present work, the literature has reported studies of surface roughness effect on flow past a bluff body with low frequency [2,5,6,[9][10][11][12][13][14][15][16][17][18][19]. It is important to mention that numerical analysis of rough bluff body aerodynamics near a ground plane is very limited, which valorizes the recent methodology proposed by Alcântara Pereira et al [10] and classified such as "hybrid control technique of vortex shedding" [20].…”

Section: Introductionmentioning

confidence: 99%

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Control and Suppression of Vortex Shedding from a Slightly Rough Circular Cylinder by a Discrete Vortex Method

et al. 2020

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A discrete vortex method is implemented with a hybrid control technique of vortex shedding to solve the problem of the two-dimensional flow past a slightly rough circular cylinder in the vicinity of a moving wall. In the present approach, the passive control technique is inspired on the fundamental principle of surface roughness, promoting modifications on the cylinder geometry to affect the vortex shedding formation. A relative roughness size of ε*/d* = 0.001 (ε* is the average roughness and d* is the outer cylinder diameter) is chosen for the test cases. On the other hand, the active control technique uses a wall plane, which runs at the same speed as the free stream velocity to contribute with external energy affecting the fluid flow. The gap-to-diameter varies in the range from h*/d* = 0.05 to 0.80 (h* is the gap between the moving wall and the cylinder bottom). A detailed account of the time history of pressure distributions, simultaneously investigated with the time evolution of forces, Strouhal number behavior, and boundary layer separation are reported at upper-subcritical Reynolds number flows of Re = 1.0 × 105. The saturation state of the numerical simulations is demonstrated through the analysis of the Strouhal number behavior obtained from temporal history of the aerodynamic loads. The present work provides an improvement in the prediction of Strouhal number than other studies no using roughness model. The aerodynamic characteristics of the cylinder, as well as the control of intermittence and complete interruption of von Kármán-type vortex shedding have been better clarified.

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Section: Physical Modelingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Control and Suppression of Vortex Shedding from a Slightly Rough Circular Cylinder by a Discrete Vortex Method

et al. 2020

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“…In a large number of experimental studies, the surface roughness is solely applied to force the transition on the boundary layer at low Reynolds numbers in order to simulate flow phenomena that physically occur at much higher Reynolds number [1,2,10,15,18,19,21,23,29,32,38,39,44]. Guven et al [18] pointed that surface roughness can cause differences on the measured drag coefficient about 60% for the same Reynolds number and these differences were attributed to some influencing factors, such as turbulence level and the surface texture.…”

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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“…As for the towering frame structures, the Reynolds number is in the supercritical regime when CWV occurs [12]. According to wind tunnel experiments [32], the RMSs of the lift coefficient C L and St are almost constant regardless of the Reynolds number. In this work, C L and St are taken as the constant values.…”

Section: Cross-wind Loadmentioning

confidence: 99%

New Approach for Vibration Suppression through Restrictors on Towering Steel Columns with Supporting Frame

Tan

Fan

et al. 2020

Mathematical Problems in Engineering

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Towering steel column with supporting frame is a typical equipment in chemical process engineering. Here, displacement restrictors are proposed to restrict the displacement of the towering and slender equipment while making the column to be structurally nonlinear and statically indeterminate. This study investigated on along-wind and cross-wind vibration characteristics of such equipment with the restrictors experimentally and numerically. A field test is carried out to measure the natural frequency and damping ratio of the 42.5-meter-high equipment vibrating in the wind, which is the prototype of the experimental model. A noncontact excitation system was applied on the experimental model to simulate the wind loads. The displacements and strains of the experimental model are collected under different frame types by changing the heights of displacement restrictors. The numerical simulation and experimental results showed that the height of displacement restrictors has a great influence on the vibration intensity of the equipment. An optimum location, recommended as about 40% of the height, could decrease the vibration intensity and enhance the safety of the equipment. Based on the results, a simplified formula in which the natural frequency and the damping ratio dominate the dynamic behavior of along-wind and cross-wind vibration, respectively, is derived from multi-degrees-of-freedom system. It could be furtherly utilized to predict the amplitude ratio of two structures and select a better design featuring an efficient vibration suppression performance. This work presents an important design guide to the frame-supporting towering process equipment and is of great significance to an economical and safety design.

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The Reynolds number dependency of the steady and unsteady loading on a slightly rough circular cylinder: From subcritical up to high transcritical flow state

Cited by 40 publications

References 28 publications

Control and Suppression of Vortex Shedding from a Slightly Rough Circular Cylinder by a Discrete Vortex Method

Control and Suppression of Vortex Shedding from a Slightly Rough Circular Cylinder by a Discrete Vortex Method

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

New Approach for Vibration Suppression through Restrictors on Towering Steel Columns with Supporting Frame

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