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I'm trying to see if I can find any literature on this specific question, but a few days of scholarly digging has been fruitless.

Given a 5" round pipe with a bluff body inserted, is there an upper bound for the Reynolds number at which the von Karman Vortex Street is no longer discernible? It seems to me that the vortices would be shed so close to the bluff body that they would be covered up by eddies in a turbulent flow (Say, Re >=100,000).

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  • $\begingroup$ Brief (only) mention here but of possible interest overall maxwell.ucdavis.edu/~cole/phy9b/notes/fluids_ch3.pdf (Better comment on Tacoma Narrows bridge than most - VS accompanied failure but was not main cause and cable slippage mentioned). $\endgroup$
    – Russell McMahon
    Mar 9, 2015 at 22:42
  • $\begingroup$ Possible interest if not value :-). Possible value . colorado.edu/MCEN/flowvis/galleries/index.html $\endgroup$
    – Russell McMahon
    Mar 9, 2015 at 22:47
  • $\begingroup$ Interest (perhaps :-) ) only: You may find the photo here of interest. I took this photo of the Paracel islands in 2009 enroute from Hong Kong to Singapore and have just found that it is 'all over the web'. No credits (and no $ :-) ) but nice to know that it appears to be the picture that people use when they want to opine about "ownership" of the islands. The relevance to this forum are the (apparently) vortex streets to the left of most but not all the islands. There are other islands not seen. $\endgroup$
    – Russell McMahon
    Jul 9, 2015 at 8:22

2 Answers 2

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I have a limited understanding of the subject, having investigated it for a specific project some while ago. That said -

I understand that the general 'opinion' is that well below Re = 100,000 turbulence effects will dominate and that Vortex Street formation will not be detectable.

This excellent 2013 article The Kármán Vortex Street - Chuck Bodeen wanders around the subject in general and has some specific comments relevant to your question plus some relevant links.

Along the way he notes:

  • This means that the vortex street begins to form at the “critical” Reynolds Number (about 40), and that, for Re above 400, turbulence in the flow shatters the regular pattern of the “street”. Another source puts the critical number at 90 and some say 100. The Reynolds number beyond which turbulence destroys the vortex street may be even higher than 400 in certain cases. A video from the Earth System Sciences laboratory at the University of California, Irvine, shows that vortex streets can form behind cylinders at Reynolds numbers around 2,000, but that turbulence dominates at Re 15,000.

However, to both confuse and inform, he cites this study Vortex Shedding from a Ground Tracking Radar Antenna and 3D Tip Flow Characteristics which investigates vortex shedding at well over Re=100,000.

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  • $\begingroup$ Right, I was onboard with the general 'opinion' and then I stumbled across the flowmeters featured here: badgermeter.com/Badger-Files/PDFs/Industrial-Products/… And unless I did the offhand calculations wrong, they are measuring vortex shedding way above Re=100,000. Needless to say I emailed the manufacturer... but I don't expect to hear back! $\endgroup$
    – Ramrod
    Mar 9, 2015 at 3:50
  • $\begingroup$ @Ramrod For interest - what is your application? (I'm an EE - But I was interested in windflow measurements. ) $\endgroup$
    – Russell McMahon
    Mar 9, 2015 at 8:33
  • $\begingroup$ I'm trying to apply various flowmeters to water pumps and achieve the best accuracy. I had originally intended to measure a turbulent flow of water relatively close to the pump source, with a Reynolds number upwards of 150,000. The more research I did, the less it seemed plausible. (I'm working on my MS EE... how I ended up working with fluids is beyond me... but I did duplicate a driver circuit for my transducer...) $\endgroup$
    – Ramrod
    Mar 9, 2015 at 8:38
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This is from examples given in the An Album of Fluid Motion 5th, 1997.

I don't know of a web address to get these images, so I will just repeat what is said about a couple of the images.

Figure on Table of contents - Karman vortex street behind a circular cylinder "The Reynolds number is about 300, which is near the upper limit for stability."
Figure 47 - Circular cylinder at R=2,000 "At this Reynolds number one may properly speak of a boundary layer ... turbulent wake."

Based on this, the Vortex Street disappears into the turbulence somewhere after Re= 2,000.

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  • $\begingroup$ Fingers crossed, attempting an Inter-Library Loan for it! $\endgroup$
    – Ramrod
    Mar 9, 2015 at 3:59

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