Period doubling in the wake of a three-dimensional cylinder

Rockwell, D.; Nuzzi, F.; Magness, C.

doi:10.1063/1.857983

Cited by 9 publications

(8 citation statements)

References 9 publications

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“…From the spanwise periodicity, it can be seen that the hairpin structure appears at the same spanwise location only on alternate shedding cycles. This spanwise subharmonic behavior implies a period-doubling scenario to one suggested in previous studies [19,20].…”

supporting

confidence: 69%

Generation of Streamwise Vortical Structures in Bluff Body Wakes

Mittal

Balachandar

1995

Phys. Rev. Lett.

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Direct numerical simulation is used to study the periodic generation and evolution of streamwise vortical structures in the near wake of a circular cylinder. It is observed that streamwise structures are formed due to stretching of core vorticity which escapes out of the core and due to stretching of small scale streamwise vorticity already present outside the core. Distinct hairpin structures are observed which play a central role in transferring vorticity out of the core. Furthermore, the hairpin structures are associated with a spanwise subharmonic mode and are thus manifestations of a period-doubling mechanism.

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supporting

confidence: 69%

Generation of Streamwise Vortical Structures in Bluff Body Wakes

Mittal

Balachandar

1995

Phys. Rev. Lett.

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“…Period doubling has been documented at the transition to chaos or turbulence in some previous studies of fluids [Gollub et al, 1980;Rockwell et al, 1991], but no period doubling was observed in these experiments. At some locations in the wake of the cylinder successive vortices were alternately strong and weak (Figure 6a).…”

Section: Flow Past a Cylinder Located Away From The Wallmentioning

confidence: 53%

“…Vortex shedding from cylinders occurs over a wide range of Reynolds numbers (approximately 5 x 10 • to 104 according to Batchelor [1967] and Schlichting [1968]), but the process is most regular within the lower part of this range [Roshko, 1954;Gaster, 1969]. The frequency of vortex shedding, n, is given by…”

Section: Flow Past a Cylinder Located Away From The Wallmentioning

confidence: 99%

Nonperiodic Eddy Pulsations

Rubin¹,

McDonald²

1995

Water Resources Research

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Recirculating flow in lateral separation eddies is typically weaker than main stem flow and provides an effective environment for trapping sediment. Observations of recirculating flow and sedimentary structures demonstrate that eddies pulsate in size and in flow velocity even when main stem flow is steady. Time series measurements of flow velocity and location of the reattachment point indicate that these pulsations are nonperiodic. Nonperiodic flow in the lee of a channel margin constriction is grossly different from the periodic flow in the lee of a cylinder that is isolated in a flow. Our experiments demonstrate that placing a flow-parallel plate adjacent to a cylinder is sutficient to cause the leeside flow to change from a periodic sequence of vortices to a nonperiodically pulsating lateral separation eddy, even if flow conditions are otherwise unchanged. Two processes cause the leeside flow to become nonperiodic when the plate is added. First, vortices that are shed from the cylinder deform and become irregular as they impact the plate or interfere with remnants of other vortices near the reattachment point. Second, these deformed vortices and other flow structures are recirculated in the lateral separation eddy, thereby influencing the future state (pressure and momentum distribution) of the recirculating flow. The vortex deformation process was confirmed experimentally by documenting spatial differences in leeside flow; vortex shedding that is evident near the separation point is undetectable near the reattachment point. Nonlinear forecasting techniques were used in an attempt to distinguish among several possible kinds of nonperiodic flows. The computational techniques were unable to demonstrate that any of the nonperiodic flows result from low-dimensional nonlinear processes.

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“…In Braun, Feudel & Guzdar (1998), an externally driven row of two-dimensional vortices was studied numerically, and it was determined that the flow developed chaos through a period-doubling cascade. A period-doubling of the flow behind a cylinder with a mild variation in diameter was observed in the experiments by Rockwell, Nuzzi & Magness (1991).…”

Section: Introductionmentioning

confidence: 85%

The evolution of a subharmonic mode in a vortex street

et al. 2005

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The development of a subharmonic three-dimensional instability mode in a vortex street is investigated both numerically and experimentally. The flow past a ring is considered as a test case, as a previous stability analysis has predicted that for a range of aspect ratios, the first-occurring instability of the vortex street is subharmonic. For the flow past a circular cylinder, the development of three-dimensional flow in the vortex street is known to lead to turbulent flow through the development of spatio-temporal chaos, whereas subharmonic instabilities have been shown to cause a route to chaos through the development of a period-doubling cascade. The three-dimensional vortex street in the flow past a ring is analysed to determine if a subharmonic instability can alter the route to turbulence for a vortex street.A linear stability analysis and non-axisymmetric computations are employed to compute the flow past a ring with an aspect ratio ${\sc ar}\,{=}\,5$, and comparisons with experimental dye visualizations are included to verify the existence of a subharmonic mode in the wake. Computations at higher Reynolds numbers confirm that the subharmonic instability does not initiate a period-doubling cascade in the wake.

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Period doubling in the wake of a three-dimensional cylinder

Cited by 9 publications

References 9 publications

Generation of Streamwise Vortical Structures in Bluff Body Wakes

Generation of Streamwise Vortical Structures in Bluff Body Wakes

Nonperiodic Eddy Pulsations

The evolution of a subharmonic mode in a vortex street

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