Experimental Investigation of Uniform-Shear Flow Past a Circular Cylinder

Extensive laboratory experiments were carried out to investigate the uniform-shear flow approaching a circular cylinder. The aim was to present the Strouhal number (St)- Reynolds number (Re) diagrams over a broad range of the shear parameter K (0 ≤ K ≤ 0.25) and at higher values of Re (600 ≤ Re ≤ 1600). An image processing technique, in conjunction with flow visualization studies, was used to secure more quantitative depictions of vortex shedding from the cylinder. The Strouhal number increases with increasing shear parameter. The drag coefficient decreases with increasing Re; also, Cd decreases as the shear parameter K increases.

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An inviscid numerical simulation of vortex shedding from an inclined flat plate in shear flow

Journal of Fluid Mechanics ◽

10.1017/s0022112077000639 ◽

1977 ◽

Vol 82 (2) ◽

pp. 241-253 ◽

Cited By ~ 15

Author(s):

Masaru Kiya ◽

Mikio Arie

Keyword(s):

Shear Flow ◽

Flat Plate ◽

Strouhal Number ◽

Vortex Shedding ◽

Initial Conditions ◽

Shear Layers ◽

Discrete Vortex ◽

Uniform Shear ◽

Uniform Shear Flow ◽

Shear Parameter

Two-dimensional vortex shedding behind an inclined flat plate in uniform shear flow is numerically investigated by means of an inviscid discrete-vortex approximation. The points of appearance of the vortices are fixed in the plane of the plate at a short distance downstream of the edges of the plate. The strengths of the vortices are determined from the Kutta condition. On the assumption that the steadily periodic flow patterns are independent of initial conditions, the numerical calculations are performed for an inclined flat plate immersed in an incompressible fluid which is set in motion impulsively from rest with the velocity profile of uniform shear flow. The results of analysis show that the Strouhal number of vortex shedding and the time-averaged values of other hydrodynamic characteristics of the flow such as the outer-edge velocity of the separated shear layers, the convective velocity of the shear layers and the drag force exerted on the plate vary closely linearly with the shear parameter of the approaching shear flow. A linear relation between the Strouhal number and the shear parameter is confirmed by an air-tunnel experiment. The effects of the shear parameter on the calculated vortex patterns in the wake are also presented.

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Vortex shedding from a circular cylinder in moderate-Reynolds-number shear flow

Journal of Fluid Mechanics ◽

10.1017/s0022112080001899 ◽

1980 ◽

Vol 101 (4) ◽

pp. 721-735 ◽

Cited By ~ 80

Author(s):

Masaru Kiya ◽

Hisataka Tamura ◽

Mikio Arie

Keyword(s):

Reynolds Number ◽

Circular Cylinder ◽

Shear Flow ◽

Vortex Shedding ◽

Transverse Velocity ◽

Number Range ◽

Uniform Shear ◽

Reynolds Number Range ◽

Moderate Reynolds Number ◽

Shear Parameter

The frequency of vortex shedding from a circular cylinder in a uniform shear flow and the flow patterns around it were experimentally investigated. The Reynolds number Re, which was defined in terms of the cylinder diameter and the approaching velocity at its centre, ranged from 35 to 1500. The shear parameter, which is the transverse velocity gradient of the shear flow non-dimensionalized by the above two quantities, was varied from 0 to 0·25. The critical Reynolds number beyond which vortex shedding from the cylinder occurred was found to be higher than that for a uniform stream and increased approximately linearly with increasing shear parameter when it was larger than about 0·06. In the Reynolds-number range 43 < Re < 220, the vortex shedding disappeared for sufficiently large shear parameters. Moreover, in the Reynolds-number range 100 < Re < 1000, the Strouhal number increased as the shear parameter increased beyond about 0·1.

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The formation mechanism and shedding frequency of vortices from a sphere in uniform shear flow

Journal of Fluid Mechanics ◽

10.1017/s0022112095000905 ◽

1995 ◽

Vol 287 ◽

pp. 151-171 ◽

Cited By ~ 93

Author(s):

Hiroshi Sakamoto ◽

Hiroyuki Haniu

Keyword(s):

Reynolds Number ◽

Shear Flow ◽

Formation Mechanism ◽

Vortex Shedding ◽

Uniform Flow ◽

Sphere Diameter ◽

Uniform Shear ◽

Uniform Shear Flow ◽

Vortex Loops ◽

Shear Parameter

Experiments to investigate the formation mechanism and frequency of vortex shedding from a sphere in uniform shear flow were conducted in a water channel using flow visualization and velocity measurement. The Reynolds number, defined in terms of the sphere diameter and approach velocity at its centre, ranged from 200 to 3000. The shear parameter K, defined as the transverse velocity gradient of the shear flow non-dimensionalized by the above two parameters, was varied from 0 to 0.25. The critical Reynolds number beyond which vortex shedding from the sphere occurred was found to be lower than that for uniform flow and decreased approximately linearly with increasing shear parameter. Also, the Strouhal number of the hairpin-shaped vortex loops became larger than that for uniform flow and increased as the shear parameter increased.The formation mechanism and the structure of vortex shedding were examined on the basis of series of photographs and subsequent image processing using computer graphics. The range of Reynolds number in the present investigation, extending up to 3000, could be classified into three regions on the basis of this study, and it was observed that the wake configuration did not differ substantially from that for uniform flow. Also, unlike the detachment point of vortex loops in uniform flow, which was irregularly located along the circumference of the sphere, the detachment point in shear flow was always on the high-velocity side.

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