Vorticity distribution of vortex street in the wake of a circular cylinder.

Okude, Muneshige; Matsui, Tatsuya

doi:10.2322/jjsass1969.37.582

Cited by 6 publications

(11 citation statements)

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“…Similar verifications were reported (Re = 140) by Okude & Matsui (1987) who used both hot-wire and visualization techniques and by Green & Gerrard (1991) (Re = 80) using optical interferometry. Using hot wires, Okude & Matsui (1990) measured the vorticity distribution in a cylinder wake (Re = 140) and found it to be in reasonable agreement with (3). A number of models have been used to match, at least kinematically, experimental and numerical data in several different turbulent flows (e.g.…”

Section: Velocity and Vorticity Distributions Within A Vortex: A Briesupporting

confidence: 57%

“…The circulation within the vortex core is estimated by (r). Provided the turbulent vortex may be modelled by the Oseen vortex (this is justified in from the Oseen vortex model; 0 , Cantwell & Coles (1983);0 , Kiya & Matsumura (1985); *, Bloor & Gerrard (1966); V, Schmidt & Tilmann (1972); +, Green & Gerrard (1991); X, Okude & Matsui (1990).…”

Section: €I Circulationmentioning

confidence: 99%

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A study of turbulent vortices in the near wake of a cylinder

Zhou

Antonia

1993

J. Fluid Mech.

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Turbulent vortices in the wake of a circular cylinder have been examined in some detail following their detection by a method based on vorticity concentration and circulation. The experimental data were obtained at a Reynolds number Re = 5600 (based on the free-stream velocity and cylinder diameter) with an array of eight X-wires aligned in the plane of mean shear. Distributions of conditionally averaged vorticity and circumferential velocity within vortices are in reasonable agreement with those inferred from an Oseen vortex. The conditionally averaged streamwise velocity distribution through the vortex centre has a maximum at the centre, implying a vortex convection velocity greater than the local mean velocity. An Oseen vortex model reproduces the measured mean velocity and Reynolds stresses reasonably well. Results are also given for the streamwise variations of vorticity concentration, circulation and size of the vortices.

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Section: Velocity and Vorticity Distributions Within A Vortex: A Briesupporting

confidence: 57%

Section: €I Circulationmentioning

confidence: 99%

A study of turbulent vortices in the near wake of a cylinder

Zhou

Antonia

1993

J. Fluid Mech.

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“…Earlier experimental verification of (1.2) for the vorticity was observed by Okude & Matsui (1987a) using both hot-wire and visualization techniques and by Green & Gerrard (1991) using optical interferometry. Also using hot wires, Okude & Matsui (1987b) measured the vorticity distribution in a cylinder wake (R d = 140) and found it to be in reasonable agreement with (1.2). Mi & Antonia (1994), using also hot-wire measurements in a wake cylinder (R d = 98), verified (1.2) for the vorticity.…”

Section: Introductionsupporting

confidence: 54%

Momentum and heat transport in a three-dimensional transitional wake of a heated square cylinder

Djenidi

Antonia

2009

J. Fluid Mech.

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The transport of momentum and a passive scalar (temperature) in a three-dimensional transitional wake of a heated square cylinder has been carried out through direct numerical simulations using the lattice Boltzmann method at a Reynolds number Rd = 200 (d is the cylinder diameter) and a Prandlt number of 0.7. The simulations shows that while momentum and heat are transported by vortical structures, heat is in general more effectively transported than momentum. It is argued that the nature of the structural flow is responsible for the longitudinal heat flux uθ being larger than the lateral one vθ in the wake region extending up to 45d. It was shown that a gradient transport model could, to a first-order approximation, be used to model uv but would be less accurate for modelling vθ. Also the Reynolds analogy between momentum and heat transports is not verified in this flow. The fluctuating temperature field presents thermal structures similar to the velocity structures with, however, a different spatial organization. In addition the analogy between fluctuating turbulent kinetic energy and the temperature variance is relatively well satisfied throughout the wake flow.

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“…Studies of vorticity fields were performed using numerical and visual methods (Green and Gerrard, 1993;Okude and Matsui 1989). The author investigates vorticity around a cylinder based on three dimensional velocity measurements in radial directions to the cylinder.…”

Section: Introductionmentioning

confidence: 99%

Vorticity Fields on Flow with Vortex System

Yulistiyanto

2009

JTS ITB

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The flow around a circular cylinder mounted normal to the channel bed is essentially a three-dimensional one. The flow upstream undergoes a separation of the turbulent boundary layer and rolls up to form a flow system, known as horseshoe vortex, which is swept around the cylinder. This vortex system plays an important role, if the bed material is movable. The shear stress of the vortex system is responsible to the bed erosion. The shear stress depends on the velocity gradient, may be presented as the vorticity. This study is done to gain a better understanding of the vorticity around a cylinder, especially where the system of vortices exist. Flow measurements were used to study the vorticity fields on flow with a horseshoe vortex system around a pile. The velocity vector plots show the presence of a primary vortex upstream of the cylinder. Based on these velocity vectors, the vorticity can be analyzed by using central finite difference approximations. Results of the vorticity calculation are presented as the vorticity contours. Results of study show the greatest value of the positive-vorticity on the horseshoe vortex system is in the plane upstream of cylinder. This value decreases in the planes downstream, attaining the lowest value in the plane downstream, where the wake vortex established. The strength of the positive vorticity increases at larger Reynolds number. Underneath the field of positive vorticity, stretching around the cylinder, it appears a field of negative vorticity. This negative vorticity near the bed is high in front of the cylinder, proportional to the bed shear stress, which is responsible to the development of local scour at the movable bed. The line of zero vorticity is plotted originated at the bed, being as the separation point. It is also concluded that the maximum positive-vorticity is not necessary coincided with the center of the vortex.

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Vorticity distribution of vortex street in the wake of a circular cylinder.

Cited by 6 publications

References 0 publications

A study of turbulent vortices in the near wake of a cylinder

A study of turbulent vortices in the near wake of a cylinder

Momentum and heat transport in a three-dimensional transitional wake of a heated square cylinder

Vorticity Fields on Flow with Vortex System

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