"The point of the study was to test the predictions of conventional mathematical methods for using the swirls of air left in a bird’s wake to calculate the lift...."
"We were very surprised” that these so-called models did not work, [Stanford grad student Eric] Gutierrez said. They all were derived from the flight of fixed-wing airplanes and assumed that with bird flight, as with airplanes, the swirling air, or vortexes, left in the wake of flight stayed the same....
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२१ टिप्पण्या:
Yeah. The models were wrong. Just ask the CAGW people about the accuracy of models.
In one of the prequels to Asimov's Foundation series (set at least a couple of dozen millennia from now) Hari Seldon is studying turbulence and decides psychohistory is an easier problem.
Okay, I'll just say it. The bird wearing goggles is pretty darn cute.
Maybe next they can give it a WWI Aviator scarf.
I am Laslo.
Everything flies by throwing air downwards.
If you assume more, like steady-state for instance, you can predict more, but the assumption here would be wrong.
The problem with assumptions is that the Navier-Stokes equations do what they assume, not what you assume.
One of the coolest things is to stand under a flock of birds (or even a single hawk!) flying so low you can hear the air swoosh through their beating wings.
If you think is hard to understand, try to understand how bumblebees fly.
The wing sweeping is a bit like a partial spin of a "somewhat crappy" helicopter propeller, Dickinson said, but the angle to the wing also creates vortices in the airlike small hurricanes. The eyes of those mini-hurricanes have lower pressure than the surrounding air, so, keeping those eddies of air above its wings helps the bee stay aloft.
It's still not easy.
a Chinese research team led by Lijang Zeng of Tsinghua University glued small pieces of glass to bees and then tracked reflected light as they flew around in a laser array.
Back in my engineer days, we were working in a trailer at the wind tunnel site until the building was finished. We had a lot of flies buzzing around as we left the trailer door open a lot.
Engineers being engineers, a couple of guys would catch flies and glue little flags attached to threads to the flies. Then they would fly around towing the tiny flags like banners towed by airplanes over the beach.
They couldn't go very fast and, if they got too close and were annoying, you could grab the flag and throw the fly to the other side of the trailer.
Engineers are kind of like that.
When I clicked on the video, I got Bill Maher breaking his silence on something....
And watched for about a minute thinking Althouse had gone all meta on me with the parrot particle vortices.
MayBee said...
"One of the coolest things is to stand under a flock of birds (or even a single hawk!) flying so low you can hear the air swoosh through their beating wings."-- A few years ago we were picking up our winter's supply of hay from the stacks out in a farmer's field. As the farmer baled his hay under clear blue skies on the west slope of the Bridgers, we pulled fresh bales off the stacks and put them on our trailer. Hawks circled above, and would dive to pick off the occasional vole sent scurrying by the baling operation. Of course, nothing could be heard above the clatter of machinery. That is until there came the sound of the fabric of the sky being ripped apart as a big golden eagle stooped on one of the hawks. The eagle missed the hawk and pulled out of it's dive right in front of us and just inches from the ground. Hard to believe how loud it was. Wow!
Should we give politicians similar rose colored glasses, or take them away?
Here's Donald Trump being "lased".
We have been studying flight for centuries and seriously throwing brains and cash at it ever since Kitty Hawk. Untold trillions and we are still guessing how it works. The behavior of a vortex is both obvious and mysterious. We burn up supercomputers running equations that might just approximate it, a little bit, someday. Meanwhile a parrot just "does" the math, and flies.
But as noted above, the global systems of turbulence in the oceans of air and water have been modeled perfectly, so that we know with complete confidence their least evolutions unto the days of our great-great-great grandchildren. Therefore shut up and submit, you deniers.
So cool, Larry Day. What a gift to hear!
"We were very surprised” that these so-called models did not work, "
Complicated systems and models don't always mix.
As noted above, there are other models where this occurs. Kudos to any scientist that say we were surprised and this didn't work, now let's figure out why and try something else.
Larry Day...
Just an idea...
If you can put goggles on a small parrot, it should be easy to put a microphone on a large bird of prey to capture those sounds and synchronize with video.
I must mention that the parrot was used in this study only because it accepted the wearing of goggles, unlike two other birds the researchers tried.
The proper bird to use would have been a European swallow, preferably as the bird attempted to carry a coconut by grasping its husk.
He looks so fly. Bet he didn't give the goggles back.
Amazing how many questions are still left for science to solve. Why are some countries underdeveloped? What is turbulent flow. What explains plant morphology? How do plants learn their numbers? Who teaches Accounting for Daisies?
IIRC Derek Lowe links to a paper on avian metabolism that starts "We trained two sparrows to fly in a wind tunnel while wearing respirator masks..."
and he remarks "This paper should have ended there. Nothing they discovered in the study was going to beat that opening line."
Fred Drinkwater: Derek Lowe is a very funny guy. Love his postings on chemistry lab misadventures: "Don't Try This At Home" on a grand scale.
"One of the coolest things is to stand under a flock of birds (or even a single hawk!) flying so low you can hear the air swoosh through their beating wings."
When I was wooing my wife , we sat on a Cape Cod beach where I made a very similar comment.
Within a minute a flock of plovers flew past. As they tilted their wings in unison we could hear a Whoosh". She thought I must be a modern St. Francis.
Also, I was fishing on the banks of the Delaware, when all at once the sky suddenly darkened, I heard a "whump" and felt the pressure wave from the wings of young Bald Eagle as he passed only 12 feet overhead.
Wicked cool.
, I heard a "whump" and felt the pressure wave from the wings of young Bald Eagle as he passed only 12 feet overhead.
Amazing.
It's weird how rare it is to hear that sound from the birds. After hearing a large hawk fly, I can only imagine how an eagle must sound.
It was a long time until I heard it again, and it was a flock of geese. Now I try to stand still to hear it, in anticipation. A little flock of black birds I heard last month - starlings probably- sounded like whispers.
@Mikee: What? Tucked beneath the dorsal guiding feathers?
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