You know those shark fin antennas cars started using to lessen drag and remove another source of noise from the cabin? Now biologists and engineers at Harvard University and University of South Carolina are proposing that sharkskin may further improve aerodynamic efficiency, potentially making cars, planes and even wind turbines more efficient.
The work of a dedicated team of evolutionary biologists and engineers from the two educational institutions is detailed in the Journal of the Royal Society Interface, penned by James Weaver of the Wyss Institute for Biologically Inspired Engineering at Harvard, and Hossein Haj-Hariri, dean of engineering and computing at the University of South Carolina, among others. The research was supported by the US Office of Naval Research and the National Science Foundation.
The idea isn’t as far fetched as it might seem, since sharks and aircraft function in much the same way — efficient movement through a medium (water and air, respectively) using the body shapes to reduce drag and create lift. And when you think about efficient auto aerodynamics, the onus is on reducing drag and providing downforce (the opposite of lift).
The research focused on denticles, the small scales that cover a shark’s body and aid the shark in moving efflorlessly through water. They’re similar to human teeth but have a different function. Initially, the team set out to research the denticles’ drag-reducing qualities, but as team members delved deeper, they found their shapes were also suited to create lift.
The team studied the shortfin Mako shark, the fastest shark in the world, and found that its denticles have three raised ridges. Using micro-CT scanning, the team imaged, modelled and 3D-printed denticle shapes onto the curved part of a wing. The airfoil, as it is called, is responsible for the lift and drag that allows an airplane to fly.
Researchers tested 20 different denticle sizes and positioning inside a water flow tank. They found that not only did they effectively reduce drag, they also significantly increased lift, acting as low-profile vortex generators — the passive aerodynamic devices on cars and planes that alter how air flows over the surface of body panels, affecting aerodynamics, most of which today have simple blade-like designs.
“These shark-inspired vortex generators achieve lift-to-drag ratio improvements of up to 323% compared to an airfoil without vortex generators,” said August Domel, a Ph.D. student at Harvard’s Graduate School of Arts and Sciences and co-first author of the paper. “With these proof-of-concept designs, we’ve demonstrated that these bioinspired vortex generators have the potential to outperform traditional designs.”
“This research not only outlines a novel shape for vortex generators, but also provides insight into the role of complex and potentially multifunctional shark denticles,” added George Lauder, the Henry Bryant Bigelow Professor of Ichthyology and professor of biology in the Department of Organismic and Evolutionary Biology, and another co-author of the research.
There is no indication of how and when the research would make it through to the real world of auto production, but the Harvard Office of Technology Development has protected the intellectual property relating to the project, and is exploring commercialization opportunities.