The wave under her wings

It’s a common sight: pelicans glide along the waves right along the shore. These birds make this type of surfing look effortless, but in fact the physics that give them a big boost isn’t straightforward.

Researchers at the University of California at San Diego recently developed a theoretical model that describes how the ocean, wind, and birds interact in flight in a recent article in Movement Ecology.

UC San Diego Mechanical Engineering Ph.D. Student Ian Stokes and advisor Professor Drew Lucas of the Department of Mechanical and Aerospace Engineering at UC San Diego and the Scripps Institution of Oceanography found that pelicans can fully offset the energy they consume in flight by taking advantage of wind updrafts, which are created by waves through so-called waves – float slope. In short, by practicing this behavior, sea birds use the winds created by breaking waves to stay airborne.

The model could be used to develop better algorithms for controlling drones that have to fly over water for long periods of time, the researchers said. Possible uses don’t stop there.

American white pelican, copyright Glyn Sellors, from the Surfbirds Galleries

“There is a community of biologists and ornithologists who are studying the metabolic cost of flight in birds who can take advantage of them and seeing how their research relates to our estimates from theory. Our model also generates a basic forecast for the winds generated by the passing swell. This is important for physicists studying how the ocean and atmosphere interact to improve weather forecasting, ”Stokes said.

“This is an interesting project because it shows how the waves actually move the air and create wind. If you are a savvy bird, you can tweak how you move to track waves and take advantage of those updrafts. Since seabirds travel long distances to find food, the benefits can be significant, ”said Lucas.

Of course, Stokes and Lucas weren’t the first scientists to study the physics of the atmosphere, where pelicans and other birds are hardwired to save energy for other activities. For centuries, humans have been inspired by the sight of birds that use the force and patterns of the winds to fly.

That’s how it started with Stokes, who is now in his sophomore year at UC San Diego. A student at UC Santa Barbara, Stokes, a surfer and windsurfer in his spare time, needed a project for his physics class and thought of the birds that would accompany him on the waves. Upon closer inspection, he saw the connection between their flight dynamics and studying fluid dynamics in the environment, a specialty of scientists at UC San Diego. The project eventually turned into a master’s thesis with Lucas, who was inspired by oceanographers at Scripps trying to understand the interactions between the ocean and the atmosphere.

Waves soaring is just one of the many behaviors in seabirds that use the energy in their environment. Using these predictable patterns, the birds can search, travel, and find mates more effectively.

“When we appreciate their mastery of the fluid, ever-changing marine environment, we gain insight into the fundamental physics that shape our world,” said Lucas.



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