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Harvard Researchers Design Shark-Inspired Airfoil

SEAS
The John A. Paulson School of Engineering and Applied Sciences sign stands in front of Pierce Hall.

Researchers from Harvard and the University of South Carolina have developed a new kind of airfoil, inspired by shark skin, that may improve lift in aircrafts.

Mehdi Saadat, an Organismic and Evolutionary Biology postdoctoral fellow, and August “Gus” Domel, a Materials Science and Mechanical Engineering doctoral student, joined Ichthyology Professor George V. Lauder to design the airfoil, a cross section of an airplane wing.

Combining their knowledge of shark biology and aerodynamics, the team examined denticles, small projections that are made of the same material as teeth, on shark skin.

“Once you actually put that skin under a microscope and you zoom in and you look at the small features, you realize they actually consist of many complex morphological structures on this skin,” Saadat said. “Intuitively, the most important hypothesis out there was that it’s for reducing drag.”

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Saadat and Domel thought about it differently. They hypothesized that shark denticles could produce vortices—essentially a whirling body of air, like a tornado—and that these vortices could improve the shark’s lift, rather than just drag, while swimming. Whereas drag is the resistive force moving parallel and in the opposite direction to the shark’s forward motion, lift is the force moving perpendicular to the motion.

The researchers decided to test whether these denticles could have a similar effect on mechanical aircraft. In particular, they studied the denticles of the mako, the world’s fastest shark.

“We take one of these denticles and we make a representative model,” Domel said. “We put it on the airfoil in different configurations.”

Their experiments confirmed their hypothesis: the denticles significantly increased the airfoil’s potential to generate lift and also reduced drag to a lesser extent. Domel said the discovery could make many aerial devices more efficient.

“If you have an airplane, if you’re increasing your lift and decreasing your drag, the plane has to use less fuel to propel itself forward as well as stay in the air,” Domel said. “You can ultimately benefit the energy of the system, whether it’s generating energy via a wind turbine or reducing energy for an airplane.”

Domel and Saadat said interdisciplinary collaboration was key to their breakthrough. They said they benefited from the expertise of Lauder, as well as Applied Mechanics Professor and materials scientist Katia Bertoldi, Wyss Institute Senior Research Scientist James Weaver, and Dean of Engineering and Computing at the University of South Carolina Hossein Haj-Hariri.

“I feel like in any collaborative project, if you put the right teams together, at the interface of all of that, that’s where the magic happens.” Saadat said.

“You have all the right pieces of the puzzle. And when you have not only the right pieces but also pieces that are all really good at what they do, it really makes for a beautiful collaboration,” Domel added.

—Staff writer Amy L. Jia can be reached at amy.jia@thecrimson.com. Follow her on Twitter @AmyLJia.

—Staff writer Sanjana L. Narayanan can be reached at sanjana.narayanan@thecrimson.com.

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