Arthur T Knackerbracket has processed the following story:
In looking up at the sky during these early weeks of spring, you may very well see a flock of birds moving in unison as they migrate north. But how do these creatures fly in such a coordinated and seemingly effortless fashion?
Part of the answer lies in precise, and previously unknown, aerodynamic interactions, reports a team of mathematicians in a newly published study. Its breakthrough broadens our understanding of wildlife, including fish, who move in schools, and could have applications in transportation and energy.
"This area of research is important since animals are known to take advantage of the flows, such as of air or water, left by other members of a group to save on the energy needed to move or to reduce drag or resistance," explains Leif Ristroph, an associate professor at New York University's Courant Institute of Mathematical Sciences and the senior author of the paper, which appears in the journal Nature Communications.
"Our work may also have applications in transportation—like efficient propulsion through air or water—and energy, such as more effectively harvesting power from wind, water currents, or waves."
The team's results show that the impact of aerodynamics depends on the size of the flying group—benefiting small groups and disrupting large ones.
"The aerodynamic interactions in small bird flocks help each member to hold a certain special position relative to their leading neighbor, but larger groups are disrupted by an effect that dislodges members from these positions and may cause collisions," notes Sophie Ramananarivo, an assistant professor at École Polytechnique Paris and one of the paper's authors.
[...] Here, they concluded that flow-mediated interactions between neighbors are, in effect, spring-like forces that hold each member in place—just as if the cars of a train were connected by springs.
However, these "springs" act in only one direction—a lead bird can exert force on its follower, but not vice versa—and this non-reciprocal interaction means that later members tend to resonate or oscillate wildly.
"The oscillations look like waves that jiggle the members forwards and backwards and which travel down the group and increase in intensity, causing later members to crash together," explains Joel Newbolt, who was an NYU graduate student in physics at the time of research.
The team named these new types of waves "flonons," which is based on the similar concept of phonons that refer to vibrational waves in systems of masses linked by springs and which are used to model the motions of atoms or molecules in crystals or other materials.
"Our findings therefore raise some interesting connections to material physics in which birds in an orderly flock are analogous to atoms in a regular crystal," Newbolt adds.
More information: Joel W. Newbolt et al, Flow interactions lead to self-organized flight formations disrupted by self-amplifying waves, Nature Communications (2024). DOI: 10.1038/s41467-024-47525-9
(Score: 3, Insightful) by gznork26 on Saturday May 04, @12:16PM
In other words, single birds in flight are an avian gas; a few flying around together are a liquid, and an organized floch is a solid mass of bird. But over a certain size, imperfection introduce flaws which can fracture the flock crystal. Love it!
Khipu were Turing complete.
(Score: 4, Informative) by Anonymous Coward on Saturday May 04, @01:12PM
Geese are the most obvious case of a flock that organizes itself for improved aerodynamics (see below). Behavior of other, less organized flocks has also been analyzed. Here's the abstract of a paper from 1978 that includes earlier references: https://www.jstor.org/stable/2460047 [jstor.org]
The classic paper mentioned above by Lissaman and Shollenberger (1970) is referenced in the paper in tfa. It's discussed in this retrospective from 2016, https://journals.biologists.com/jeb/article/219/18/2778/15470/Lissaman-Shollenberger-and-formation-flight-in [biologists.com]
(Score: 3, Funny) by mcgrew on Saturday May 04, @03:09PM
Flock off.
mcgrewbooks.com mcgrew.info nooze.org
(Score: 1) by Runaway1956 on Saturday May 04, @04:13PM (2 children)
To study bird flight, researchers study some artificial "wings" flapping in water. If you haven't already, you should click the link, and watch the video.
These "researchers" don't understand that the density and pressure in the atmosphere are very different than the density and pressure in water? Water's mass is many times greater than any comparable volume of air.
Researchers don't mention what kind of "wing" they are studying, either. Not all bird's wings are alike. Owls are about the most silent of flyers, and the structure of their wings is quite different from the wings of, say, most chickens, which make a lot of noise, for very limited flight. Soaring birds with huge wing spans are very different from birds that constantly beat their wings to stay aloft. What bird did their plastic 3-D printed "wings" replicate? What kind of feathers were these "wings" supplied with? Not only are wings structurally different among birds, but the feathers perform their jobs differently, individually and collectively.
Some few birds can "fly" underwater. Ducks, geese, seagulls, and other birds that capture marine life can go underwater, and "fly". They certainly don't "fly" underwater as fast or efficiently as they fly through the air. Physics forbids that sort of nonsense.
These "researchers" need to be blacklisted from wasting research funds, and drawing fantastic conclusions from ridiculous conslusions. Had they drawn any conclusions about schooling fish, they would look less ridiculous here, but even so, it appears they "researched" relatively inflexible "wings" or fins, without any scales or feathers.
This is the kind of "research" you might expect from junior high school students. There is so much wrong with the research and the conclusions, there is no good starting point, or ending point, to pick it all apart.
(Score: 2, Interesting) by Runaway1956 on Saturday May 04, @04:22PM (1 child)
Oh, I didn't even mention that the "birds" in the study are "flying" in circles. While birds do indeed fly in circles sometimes, migrating formations tend to fly in nearly straight lines, therefore never flying back through already disturbed air flows and air patterns. Maybe a pilot can weigh in here, explaining the difference between a holding pattern, and directed flight across a sea or a continent.
(Score: 1, Informative) by Anonymous Coward on Sunday May 05, @01:19PM
Yes, Whirling Arm test devices, mentioned at the beginning of this history,
https://www.grc.nasa.gov/www/k-12/WindTunnel/history.html [nasa.gov]
It's a fascinating story of engineering development, here is a teaser from near the beginning: