Flow Around a Circular Cylinder: Aspects of Fluctuating Lift

Norberg, C.

doi:10.1006/jfls.2000.0367

Cited by 235 publications

(117 citation statements)

References 44 publications

(60 reference statements)

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“…Plots of the computed Strouhal number and mean drag variation with Reynolds number are compared with experimental results obtained from the review on flow around circular cylinders by Zdravkovich (1997) and Norberg (2001). Figure 4 shows a good agreement between the Strouhal (St) number calculated in the present work and experimental results.…”

Section: Validation For One Cylindersupporting

confidence: 66%

Fast numerical simulation of vortex shedding in tube arrays using a discrete vortex method

Sweeney

Meskell

2003

Journal of Fluids and Structures

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Vortex shedding may occur in tube arrays, resulting in strong excitation forces at discrete frequencies. In the past the Strouhal numbers governing vortex shedding in these systems were determined primarily by experiment. This paper presents a computationally inexpensive method of numerical simulation for the unsteady flow through a rigid normal triangular tube array which determines both the frequency of vortex shedding and the instantaneous flow structure. The technique used is based on a discrete vortex method similar to the cloud-in-cell approach which has been applied to flow problems for small numbers of cylinders. However, in the current implementation the flow velocity calculation is carried out on an unstructured grid using a finite element discretization. Thus, the complex geometry associated with a tube array can be easily accommodated. The method, referred to as the "Cloud-in-element" method, is validated for the standard case of flow over a single cylinder and then applied to flow through a normal triangular array with a pitch-to-diameter of 1.6. The Reynolds number is 2200. The Stouhal number obtained from the numerical simulation is 1.27, which is within 6% of the value available in the literature. Qualitatively, the vortex shedding pattern obtained is in agreement with published flow visualization.

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Section: Validation For One Cylindersupporting

confidence: 66%

Fast numerical simulation of vortex shedding in tube arrays using a discrete vortex method

Sweeney

Meskell

2003

Journal of Fluids and Structures

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“…Naturally, the Re effect on the narrow wake is significant and may behave similarly to an isolated cylinder wake, where St is almost constant for Re= ͑6 ϫ 10 2 ͒ -͑3 ϫ 10 3 ͒ but reduces considerably from Re= 3 ϫ 10 3 to 2 ϫ 10 4 . 25,[38][39][40] The St behavior is linked to the vortex formation length, which is insensitive for Re= ͑6 ϫ 10 2 ͒ -͑3 ϫ 10 3 ͒ but shrinks exponentially from Re= 3 ϫ 10 3 to 2 ϫ 10 4 . 28,41,42 Given an exponentially reducing vortex formation length associated with the upstream cylinder for Re …”

Section: Typementioning

confidence: 99%

“…The variation in St exhibits the same trend as in an isolated cylinder wake, whose St reduces from Re= 3 ϫ 10 3 to 2 ϫ 10 4 . 25,[38][39][40] The flow of type 4D consists of two coupled vortex streets, either in antiphase or in phase ͓Figs. 15͑j͒ and 15͑k͔͒.…”

Section: -9mentioning

confidence: 99%

Reynolds number effect on the wake of two staggered cylinders

et al. 2009

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This work aims to investigate, based on the measured/reported Strouhal number ͑St͒ and the flow structure, the Reynolds number ͑Re͒ effect on the wake of two identical cylinders with a diameter of d over P ‫ء‬ = P / d = 1.2-4.0 and ␣ = 0°-90°, where P is the center-to-center spacing between the two cylinders and ␣ is the angle of incident flow with respect to the line through the two cylinder centers. The Re range examined is from 1.5ϫ 10 3 to 2.0ϫ 10 4 . Two hotwires were used to measure St simultaneously behind each of the two cylinders. The St-Re relationship is classified into four distinct types, i.e., types 1-4. Each is linked to distinct initial conditions, viz., interactions between the four shear layers around the cylinders. Type 1 occurs at small P ‫ء‬ , not exceeding 1.25. The two cylinders act like a single body, producing a single St across the wake throughout the range of Re examined. On the other hand, type 2 occurs at small ␣ ͑Ͻ10°͒. Although single valued, the St in type 2 displays a sudden jump with increasing Re due to a switch in the shear layer, separated from the upstream cylinder, from overshooting to reattachment on the downstream cylinder ͑type 2A͒ or from reattachment to coshedding vortices ͑type 2B͒, depending on P ‫ء‬ . Type 3 is in the region of intermediate P ‫ء‬ ͓͑1.2-1.5͒-2.2͔ and ␣ ͑10°-75°͒. Two distinct St occur at low Re. The lower and the higher ranges of St are associated with the downstream and upstream cylinders, respectively. With increasing Re, the higher St collapses to the lower, which is attributed to a change in the inner shear layer, separated from the upstream cylinder, from squeezing through the gap between cylinders to reattachment on the downstream cylinder. Type 4 occurs at large P ‫ء‬ ͑Ͼ1.2-2.2͒ and again exhibits at low Re two St, above and below the Strouhal number St 0 in the wake of an isolated cylinder, both changing suddenly or progressively to St 0 with increasing Re, which results from a change in the inner shear layer, separated from the upstream cylinder, from reattachment on the downstream cylinder to forming vortices between the cylinders. These types of Re-St relationships are also connected to the flow structure modes reported in literature. The dependence of the St and St-Re relationships on P ‫ء‬ and ␣ is provided, which may be used for the prediction of St in related problems.

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“…The Reynolds number based on the cylinder diameter ranges from 60 to 250. For ow past a circular cylinder, it is well known that the vortex shedding appears at Re 47 [44] as a result of the rst instability in the wake. The above unsteady wake ow is also called 2D laminar wake regime or periodic one.…”

Section: Introductionmentioning

confidence: 99%

Features of flow past a circular cylinder with a slit

Sheng

Chen

2016

Scientia Iranica

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Abstract. The impact of a slit placed along a circular cylinder diameter, which is parallel to the incoming ow, is numerically investigated in order to nd a geometric modi cation that can help drag reduction, as well as vortex suppression, without any additional energy consumption. The drag reduction is achieved by diverting part of the uid in the front stagnation region into the low pressure zone at the back of cylinder through the slit. The Reynolds number based on the cylinder diameter, D, ranges from 60 to 250. The e ect of the slit width ratio (s=D) on the drag and lift coe cients, the Strouhal number, and the wake ow feature of the cylinder is presented. Favorable reduction of drag and lift coe cients is observed with the rising of slit width ratio. The vortex shedding generated from the slit alters the wake ow thoroughly and drives the vortex shedding derived from the cylinder surface to further downstream.

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Flow Around a Circular Cylinder: Aspects of Fluctuating Lift

Cited by 235 publications

References 44 publications

Fast numerical simulation of vortex shedding in tube arrays using a discrete vortex method

Fast numerical simulation of vortex shedding in tube arrays using a discrete vortex method

Reynolds number effect on the wake of two staggered cylinders

Features of flow past a circular cylinder with a slit

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