scholarly journals On the vortex shedding from a circular cylinder in a linear shear flow

2000 ◽  
Vol 25 (4) ◽  
pp. 85_53-85_62
Author(s):  
Shuyang Cao ◽  
Kimitaka Hirano ◽  
Shigehira Ozono ◽  
Yasuo Wakasugi
Keyword(s):  
Circular Cylinder ◽  
Shear Flow ◽  
Vortex Shedding ◽  
Linear Shear

Oblique vortex shedding from a circular cylinder in linear shear flow

2002 ◽  
Vol 31 (1) ◽  
pp. 1-24 ◽  
Author(s):  
A. Mukhopadhyay ◽  
P. Venugopal ◽  
S.P. Vanka
Keyword(s):  
Circular Cylinder ◽  
Shear Flow ◽  
Vortex Shedding ◽  
Linear Shear

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

1980 ◽  
Vol 101 (4) ◽  
pp. 721-735 ◽  
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.

Experimental Investigation of Uniform-Shear Flow Past a Circular Cylinder

1992 ◽  
Vol 114 (3) ◽  
pp. 457-460 ◽  
Author(s):  
Tae Soon Kwon ◽  
Hyung Jin Sung ◽  
Jae Min Hyun
Keyword(s):  
Circular Cylinder ◽  
Shear Flow ◽  
Strouhal Number ◽  
Vortex Shedding ◽  
Laboratory Experiments ◽  
Processing Technique ◽  
Image Processing Technique ◽  
Uniform Shear ◽  
Uniform Shear Flow ◽  
Shear Parameter

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.

Distribution of gyrotactic micro-organisms in complex three-dimensional flows. Part 1. Horizontal shear flow past a vertical circular cylinder

2018 ◽  
Vol 852 ◽  
pp. 358-397 ◽  
Author(s):  
L. Zeng ◽  
T. J. Pedley
Keyword(s):  
Circular Cylinder ◽  
Shear Flow ◽  
Vortex Shedding ◽  
Water Surface ◽  
Concentration Distribution ◽  
Three Dimensional ◽  
Swimming Velocity ◽  
Horizontal Shear ◽  
Active Particles ◽  
Micro Organisms

As a first step towards understanding the distribution of swimming micro-organisms in flowing shallow water containing vegetation, we formulate a continuum model for dilute suspensions in horizontal shear flow, with a maximum Reynolds number of 100, past a single, rigid, vertical, circular cylinder that extends from a flat horizontal bed and penetrates the free water surface. A numerical platform was developed to solve this problem, in four stages: first, a scheme for computation of the flow field; second, a solver for the Fokker–Planck equation governing the probability distribution of the swimming direction of gyrotactic cells under the combined action of gravity, ambient vorticity and rotational diffusion; third, the construction of a database for the mean swimming velocity and the translational diffusivity tensor as functions of the three vorticity components, using parameters appropriate for the swimming alga, Chlamydomonas nivalis; fourth, a solver for the three-dimensional concentration distribution of the gyrotactic micro-organisms. Upstream of the cylinder, the cells are confined to a vertical strip of width equal to the cylinder diameter, which enables us to visualise mixing in the wake. The flow downstream of the cylinder is divided into three zones: parallel vortex shedding in the top zone near the water surface, oblique vortex shedding in the middle zone and quasi-steady flow in the bottom zone. Secondary (vertical) flow occurs just upstream and downstream of the cylinder. Frequency spectra of the velocity components in the wake of the cylinder show two dominant frequencies of vortex shedding, in the parallel- and oblique-shedding zones respectively, together with a low frequency, equal to the difference between those two frequencies, that corresponds to a beating modulation. The concentration distribution is calculated for both active particles and passive, non-swimming, particles for comparison. The concentration distribution is very similar for both active and passive particles, except near the top surface, where upswimming causes the concentration of active particles to reach values greater than in the upstream strip, and in a thin boundary layer on the downstream surface of the cylinder, where a high concentration of active particles occurs as a result of radial swimming.

End-wall effects on vortex shedding in planar shear flow over a circular cylinder

2011 ◽  
Vol 42 (1) ◽  
pp. 102-107 ◽  
Author(s):  
Zhiyong Huang ◽  
Helge I. Andersson ◽  
Weicheng Cui
Keyword(s):  
Circular Cylinder ◽  
Shear Flow ◽  
Vortex Shedding ◽  
Wall Effects ◽  
Planar Shear ◽  
End Wall

Vortex Shedding in a Linear Shear Flow From a Vibrating Marine Cable With Attached Bluff Bodies

1985 ◽  
Vol 107 (1) ◽  
pp. 61-66 ◽  
Author(s):  
R. D. Peltzer ◽  
D. M. Rooney
Keyword(s):  
Shear Flow ◽  
Vortex Shedding ◽  
Bluff Body ◽  
Bluff Bodies ◽  
Near Wake ◽  
Cable System ◽  
Sheared Flow ◽  
Linear Shear ◽  
Body Shapes ◽  
Marine Cable

The present study examines the vortex street wake behavior of a flexible, helically wound, high aspect ratio marine cable in a linear shear flow. Particular attention is paid to the lock-on phenomena associated with uniform and sheared flow past the cable when it is forced to vibrate in the first mode, normal to the flow. An analysis is given of the effects on the vortex shedding and synchronization phenomena that are generated by placing distributions of spherical bluff body shapes along the span of the cable in uniform and sheared flow. The latter geometry is representative of a number of cable system deployments and has special consequencies for strumming in a shear flow. The effectiveness of these attached spheres as strumming-suppression devices is evaluated. Synchronized vibration and/or the presence of the bluff bodies significantly affected the spanwise character of the near wake cellular vortex shedding structure. The spanwise extent of the resonant, vortex-excited oscillations was significantly extended by the presence of the spheres along the cable span. This finding was particularly significant because it meant that the undesirable effects that accompanied synchronization would be extended over a longer portion of the cable span.

The interaction of a diffusing line vortex and an aligned shear flow

1985 ◽  
Vol 399 (1817) ◽  
pp. 367-375 ◽  
Keyword(s):  
Exact Solution ◽  
Circular Cylinder ◽  
Shear Flow ◽  
Kinematic Viscosity ◽  
Stokes Equations ◽  
Radial Distance ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Line Vortex ◽  
Linear Shear

An exact solution of the Navier─Stokes equations of incompressible flow, which represents the interaction of a diffusing line vortex and a linear shear flow aligned so that initially the streamlines in the shear flow are parallel to the line vortex, is presented. If Γ is the circulation of the line vortex and v the kinematic viscosity then, when Re ═ Γ/2π v is large, the vorticity of the shear flow is expelled from the circular cylinder 0 < r ≪ ( vt ) 1/2 Re 1/3 , where r is the distance from the axis of the diffusing line vortex and t the time since initiation of the flow. At larger radii a peak vorticity 0.903Ω Re 1/3 is found at a radial distance 1.26( vt )1/2 Re 1/3 , where Ω is the initial uniform vorticity in the shear flow. The vortex filament is embedded in a growing cylinder from which vorticity has been expelled, the cylinder itself being bounded by an annular region of thickness of order Re 1/3 ( vt ) 1/2 in which the vorticity is of order Ω Re 1/3 .

Oblique and cellular vortex shedding behind a circular cylinder in a bidirectional shear flow

2010 ◽  
Vol 22 (11) ◽  
pp. 114105 ◽  
Author(s):  
Zhiyong Huang ◽  
Vagesh D. Narasimhamurthy ◽  
Helge I. Andersson
Keyword(s):  
Circular Cylinder ◽  
Shear Flow ◽  
Vortex Shedding
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