The bumps on a humpback's fins inspire a new line of green-tech blades for turbines, fans, and maybe the home.
But when the shop manager produced a photograph that showed the leading edge of the long fins was indeed serrated like the teeth on a saw, Dr. Fish was intrigued and decided to investigate.
He discovered that these bumps, called tubercles, are this creature's secret weapon, allowing a whale the size of a school bus to make tight turns and capture prey with astonishing agility.
Fish, a biology professor at West Chester University of Pennsylvania, is now using this technology perfected by nature to produce fans with serrated blades that use 20 percent less electricity than traditional models. This finding contradicts conventional designs that strive for the smoothest possible edges.
To understand this phenomenon, imagine airplane wings. Pilots increase the angle of the airfoil to provide more lift. But when the angle gets too steep, the air current drags on the wing, suddenly reducing the lift and causing the aircraft to stall.
Fish found that humpback fins act a little differently. He and his colleagues tested a scale model of the whale flipper in a wind tunnel. To their surprise, the experiments revealed that significant drag occurs at a much steeper angle on the humpback fin than it does on a sleek flipper. Each tubercle redirects and channels air over the flipper, creating a sort of whirling vortex that actually improves lift, Fish says.