Tip vortex structure for a circular cylinder with a free end

Sumner, D.; Heseltine, J. L.

doi:10.1016/j.jweia.2007.06.039

Cited by 59 publications

(14 citation statements)

References 12 publications

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“…1) is due to streamwise reorientation of vorticity, or is the streamwise vorticity due to vortex structures that exist independently of the vortex shedding process as described by Etzold and Fiedler? 19 Recently the question of the origin of these mean streamwise structures has been raised, 27,32 and the analysis presented herein will demonstrate that an alternative explanation is needed.…”

Section: Introductionmentioning

confidence: 83%

Alternating half-loop shedding in the turbulent wake of a finite surface-mounted square cylinder with a thin boundary layer

2011

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The configuration and energetics of the large-scale vortex structure are presented for quasi-periodic shedding in the turbulent wake of a finite (h=d ¼ 4) square-cross-section surface-mounted cylinder protruding from a thin boundary layer (d=h ¼ 0.18). The three-dimensional large-scale structure is educed from phase averaged x-y and x-z planar data measured with particle image velocimetry (PIV). Simultaneous measurements of the surface pressure difference on either side of the obstacle were used to phase-align the PIV planar measurements. The topology of the educed structures resembles alternating half-loops interconnecting close to the base plate. The time averaging of this unsteady structure gives rise to mean streamwise vortices akin to those presented in the literature for similar geometries. This topological analysis offers a contrasting interpretation of the mean streamwise vorticity, which has, otherwise, been presumed to originate from structures generated at the leading edge of the free-end. The dynamical significance of the resolved large scale structures and unresolved fluctuating kinetic energy in the wake is presented, either part being responsible for roughly half the mean kinetic energy. A discussion of turbulence production in light of the base flow that supplies it with energy is put forward.

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Section: Introductionmentioning

confidence: 83%

Alternating half-loop shedding in the turbulent wake of a finite surface-mounted square cylinder with a thin boundary layer

2011

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“…Specifically, the flow field is strongly three-dimensional because of the free end and the cylinder-wall junction. A downward-directed velocity field (downwash) and an upward-directed velocity field (upwash) have been widely observed behind the free end and the base of rigid finite cylinders respectively (Donnert et al, 2007;Etzold and Fiedler, 1976;Kawamura et al, 1984;Park and Lee, 2000;Rostamy et al, 2012;Sumner and Heseltine, 2008;Sumner et al, 2004). Meanwhile, the structure of the vortices shedding from the finite cylinder is more diverse than the well-known Karman vortex shedding from a two-dimensional cylinder.…”

Section: Introductionmentioning

confidence: 99%

Large eddy simulation of flow around an inclined finite square cylinder

Tse

Kwok

et al. 2015

Journal of Wind Engineering and Industrial Aerodynamics

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“…It has been found that the shear layer separated from the free end of a finite cylinder has a significant effect on the wake pattern. [37][38][39][40][41][42][43] In most of these experimental studies the cylinder is vertically mounted on a flat plate. So, the approaching flows were boundary layer flows and the thickness of the boundary layer depended on the size of the flat plate.…”

Section: Introductionmentioning

confidence: 99%

Vortex-induced vibration of a circular cylinder of finite length

Zhao

Cheng

2014

Physics of Fluids

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Vortex-induced vibration (VIV) of a rigid circular cylinder of finite length subject to uniform steady flow is investigated numerically. The study is focused on the effect of the free end on the response of the cylinder. The vibration of the cylinder is confined only in the cross-flow direction. Three-dimensional Navier-Stokes equations are solved by the Petrov-Galerkin finite element method and the equation of the motion is solved for the cylinder displacement. Simulations are conducted for a constant mass ratio of 2, a constant Reynolds number of 300 and cylinder length to diameter ratios of L/D = 1, 2, 5 10, and 20. It is found that the vortex shedding in the wake of a fixed cylinder is suppressed if the cylinder length is less than 2 cylinder diameters. However, if the cylinder is allowed to vibrate, VIV happens at L/D = 1 and 2 and the response amplitudes at these two cylinder lengths are comparable with that of a 2D-cylinder. The vortices that are shed from a short cylinder of L/D = 1 and 2 are found to be generated from the free-end of the cylinder and convected toward the top end of the cylinder by the upwash velocity. They are found to be nearly perpendicular to the cylinder span. The wake flow in a vibrating cylinder with L/D greater than 5 includes the vortex shedding flow at the top part of the cylinder and the end-induced vortex shedding near the free-end of the cylinder. The phase difference between the sectional lift coefficient and the vibration displacement near the free-end of the cylinder changes from 0° to 180° at higher reduced velocity than that near the top end. Strong variation of the flow along the cylinder span occurs at reduced velocities where the lift coefficient near the free-end and that near the top end are in anti-phase with each other.

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Tip vortex structure for a circular cylinder with a free end

Cited by 59 publications

References 12 publications

Alternating half-loop shedding in the turbulent wake of a finite surface-mounted square cylinder with a thin boundary layer

Alternating half-loop shedding in the turbulent wake of a finite surface-mounted square cylinder with a thin boundary layer

Large eddy simulation of flow around an inclined finite square cylinder

Vortex-induced vibration of a circular cylinder of finite length

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