FEB 22, 2016 09:27 AM PST

Flocks of birds use ‘beautiful physics' to save energy

Fish and birds, when moving in groups, use two “gears”—one slow and another fast—in ways that conserve energy. Scientists made the discovery using a technique that mimics infinitely large schools or flocks within the confines of a New York City laboratory.

“Some beautiful physics is at work in schools and flocks, with each individual creating a wave in the fluid while also ‘surfing’ on the wave left by its upstream neighbor,” says Leif Ristroph, an assistant professor in NYU’s Courant Institute of Mathematical Sciences, who led the study.

While a lone swimmer moves at a well-defined swimming speed, larger groups take one of two speeds.

Ristroph and colleagues created a robotic “school” in which the swimmers are 3D-printed plastic wings that flap and swim around a water tank. They say the tricky part was having the wings swim in circular orbits, similar to the whirling blades of a fan or helicopter, so that each moves within the flow generated by all in their previous orbits.

By moving in a circular motion, thus establishing and responding to its own wake, a small set of wings can mimic an infinitely long array.

They found that while a lone swimmer moves at a well-defined swimming speed, larger groups take one of two speeds.

In “first gear,” each swimmer traces out the same path through the fluid and goes with the flow created by its upstream neighbor, and the school as a whole swims slowly. “Second gear” is a fast mode in which each individual flaps counter to its neighbor and against the flow it encounters.

The researchers then conducted computer simulations in an attempt to understand more about these distinct speeds. Their results, published in Nature Communications, show that the slower first mode saves on the energy required to swim—and therefore would be ideal for cruising or migrating—while the faster second gear burns more energy, but would be advantageous for fast escapes from predators.

The team sees its findings as applicable to the aerodynamics of bird flocks, with air replacing water as the flows to be navigated.

The results also yield a greater understanding of the principles of water and air flow—knowledge that could be harnessed by boats and planes to more efficiently capture energy from ocean waves or atmospheric turbulence.

Grants from the Department of Energy, the National Science Foundation, and the Institute for Complex Adaptive Matter supported the work.

Source: New York University

This article was origianlly published on futurity.org.
About the Author
  • Futurity features the latest discoveries by scientists at top research universities in the US, UK, Canada, Europe, Asia, and Australia. The nonprofit site, which launched in 2009, is supported solely by its university partners (listed below) in an effort to share research news directly with the public.
You May Also Like
NOV 12, 2018
Plants & Animals
NOV 12, 2018
Newly-Discovered Tea Plant Naturally Exhibits Little or No Caffeine
Tea is perhaps one of nature’s purest flavored drinks, and it can be brewed from not much more than some hot water and lightly-processed tea plant le...
NOV 29, 2018
Chemistry & Physics
NOV 29, 2018
Nuclear Medicine: Origin, Crisis, and Renaissance
60 years ago in the Brookhaven National Laboratory (BNL), the DOE's cutting-edge nuclear research facility located on Long Island, the invention of a n...
DEC 30, 2018
Space & Astronomy
DEC 30, 2018
Are Some Super-Earth Exoplanets Rich in Rubies and Sapphires?
Astronomers are always peeking through the lenses of their fancy space telescopes to learn more about the universe around us. One thing that captivates the...
JAN 17, 2019
Cell & Molecular Biology
JAN 17, 2019
Researchers Engineer Artificial Cell Constructs That Send Signals
Scientists are getting closer to engineering synthetic tissues that mimic natural organisms....
FEB 04, 2019
Plants & Animals
FEB 04, 2019
Researchers Discover Fluorescence in Flying Squirrels for the First Time
Best known for their innate gliding capabilities, the humble flying squirrel packs an extra flap of skin that doubles as a kite-like gliding system for gra...
FEB 19, 2019
Plants & Animals
FEB 19, 2019
A Lobster's Softer Shell Tissues Are Astonishingly Durable, New Research Claims
Lobsters are fascinating marine animals, but they’re also a delicacy in certain parts of the world. While eating lobster for dinner one evening, rese...
Loading Comments...