Vortex Shedding

[RamBeuk]

Wow. That sounds like a long train passing by.

[ryansnider]

"This apparatus is going to rip your arms off"

[CondusedMind]

Then put your finger in there

[Dejected4angel]

2:02 click to Skip the bla bla section

[edwardcyngu]

it's gonna take off.....

[Newtoon]

@NatSciDemos Hé ! Very interesting indeed. I have an itching question : is it the illustration of what happened to the Takoma bridge. We know now that the accident was not pure resonant but seems better explained by a coupling between vortices shredding and the reaction of the bridge (cables + bridge itself) ????

Quick ! An answer ! It's itching my brain ! ;-)

[NatSciDemos]

@Newtoon Yes, it is. In the Tacoma Narrows case, the wind over the roadway deck of the bridge produced vortices with a frequency of 1/5 Hz. The 5 second period of oscillation (of the bridge) was close to the period of the vortices and thus the oscillations built up in time (resonance phenomenon)>

[kevfromMA]

cool, now try to grab the rod in the middle

[MetalMaggot46]

I dare you to stick your arm in it

[noobdahunter1]

BLA BLA BLA!

[Ghelimir]

It sounds like the original Enterprise at the beginning!

[Ghelimir]

It sounds like the bridge of the original Enterprise!

[CatsRuleDogsAreTards]

i want to see what happens when that piano wire hits a watermelon

[profarrington]

Reminds me of that Gordon Lightfoot song, "The Wreck of the Edmund Fitzgerald":

"The wind in the wire made a tattletale sound..."

[profarrington]

Reminds me of that Gordon Lightfoot song, "The Wreck of the Edmund Fitzgerald":

"The wind in the wire made a tattletale sound..."

[kabbochi]

confused



[runr100]

My cat did not like this one bit!

[gr33nman]

Might this demonstration have been more effective with a nebulizer or fog machine and a well-placed light source?

[TheMick26]

Oops! I should have said shed, not shredded. But with piano wire, they are probably being shredded as well. ;o)

Either way. thanks for the post.

[TheMick26]

Thanks for the explanation and the demonstration, sir.

Try adding a little smoke so that we can actually see the vortices being shredded.

Thanks,

Mick

BTW, I'm glad you didn't have safety guards over the belts and pulleys just to satisfy OSHA seeing how those aren't the most potentially dangerous parts of the aparatus. ;o) That would make one heck of a slicer/dicer.

[NatSciDemos]

@TheMick26 The vortex shredding frequencies are of the order of KHz , so it would not be possible to see these. The wire itself is whipping around at about 10 m/s too.

[minutewalt]

@NatSciDemos Not even with the use of a high speed camera? As visceral as this is demonstration is, additional visual aid would be most welcome.

That being said, could a different demonstration be set up in a tank of transparent fluid (water being the most obvious choice) with dyes (possibly non-soluble with the tank's main liquid (ie: dyed oil in a water-filled tank)) being released by the vector(s) creating/shedding vortices? Would that slow things down enough for a more visual demonstration?

[NatSciDemos]

@minutewalt Yes. In fact, we introduce the demonstration with exactly what you suggest -- a fluid with an additive that makes the flow visible (it's called Rheoscopic Fluid).

[czgibson]

I think the German band Faust would love to have one of these things on their stage.

[andreagonellaj]

looks and sounds like a part of a @fuck buttons song!

[nebutron]

Great sounds! Stay the heck away from that thing when it's running, though: yikes!

[dawnofascendacy]

stick your finger in the vortex and see what sound it makes lololol

[KafshakTashtak]

I think the sounds are mostly due to your motor, belt, bearings and structure, finally some sound coming out of string.

[r2kordmaa]

@KafshakTashtak

oh and you think its pure coincidence that the sounds peak at piano string harmonics? sure there is noise out of the motor etc the acoustics of the apparatus could be better in that aspect, but listen to the high pitched sounds that peak and die out depending on the rotation speed and go higher and higher as the apparatus rotates faster. i bet that if you put that sound track through audio software and compared the peaks to the string frequency they would be harmonics of it

[leftovcenta]

Peru throat warblers!

[GaryHurd]

I suggest using a strobe light, and maybe a "fog" made with dry ice in water.

[katiekawaii]

2:12 - Starts sounding like a robot duck quacking.

[NatSciDemos]

@bluentes yep!

[sircantaloupe]

Some almost uneartly sounds.

I like it.