core.form-ula

Whales’ and dolphins’ speed and agility are wondrous to behold — finely tuned by evolution for efficiency and maneuverability in the water. Now researchers are working to translate these animals’ natural innovations into manmade technologies on land, air and sea.Frank Fish of West Chester University in Pennsylvania began to study the humpback whale fin while on vacation in Boston in the early 1980s, where he saw a statue of a humpback whale in a shop in Quincy Market. He assumed it was sculpted incorrectly, because the figure showed bumps along the front edge of the flipper.

“It just didn’t make sense,” Fish said. One of the cardinal lessons of fluid mechanics is that the leading edge of a fin or wing needs to be smooth to create the flow that provides lifting force.

Fish mentioned it to the shop owner, who pulled out a photo of a humpback whale, clearly showing the bumps in front.

“I became sort of obsessed with it,” Fish said. He called around to locate a specimen to measure and model the fins, and ended up on a contact list for those interested in stranded marine mammals.

Years later, Fish got a call that a humpback whale was dead on the New Jersey shore, and he could have a fin. The fin wouldn’t fit in his car and he ended up slicing it in three pieces to make it fit. “I was absolutely afraid I’d be stopped by state troopers with my car full of flesh in black plastic bags,” he recalled.

The fin languished for some more years in the freezer while Fish looked for a way to make a cast of it. Eventually, he had it sliced into one-inch sections and then photographed them.

Finally, Fish had the information he needed to create and test a model of the humpback’s flipper. Through modeling and wind tunnel studies done by colleagues, Fish determined that the bumps on the whales’ fins do indeed serve an important purpose. Among its advantages is it overcomes what’s known as “stall” — the angle at which a wing no longer experiences lift, but only drag, so it loses its ability to act as an airfoil.

“The full fin could delay stall. It could decrease drag in certain instances, and it could improve lift,” Fish said.

To feel this, imagine sticking your palm out a car window, palm down and parallel to the ground. All you feel is drag. If you start to tilt the front edge up, you feel the backward force of drag, which gets a little stronger, but you also feel the upward force of lift. If you keep increasing the angle of your hand, eventually the lift force goes away.

The whale fin can tilt to a higher angle before experiencing stall. On the whale, the delayed stall means it can make tight turns, a crucial skill for the way it hunts schooling fish like herring, swimming around them in tighter and tighter circles and then shooting up through the column of fish and swallowing them.

But the finding has lots of applications on land, too. Putting bumps across the leading edge of a wind turbine means the blades can be oriented at a higher angle to capture more of the wind without worrying about stall — which can damage the turbines.

“If it’s big and one blade stalls, it can start to shake itself apart,” Fish explained.

Fish has teamed up with Stephen Dewar to form the Toronto-based company WhalePower to commercialize this approach.

They are also targeting industrial fans. “We can move more air and ventilate more area with fewer blades,” Fish added.

The whale-inspired fans also use 20 percent less power and operate with one-fifth the noise of a standard fan, Dewar said.

In newer work, Fish is trying to understand the way the dolphin fluke — what you might think of as the back “fin” — propels the dolphin and how that works compared to marine propellers.

Marine propellers are rigid, and have a “sweet spot” speed where it gets the maximum efficiency, Fish said.

“The dolphin flukes seem to adjust themselves so they can maintain a high efficiency over a wide range of swimming speeds. We’re investigating why that is.”

It appears that the dolphin has the ability to change its fluke shape to maintain efficiency, Fish said. Fish presented his work at a meeting of the Society for Experimental Biology in Marseille, France this week.

“His discovery of the functional role of the ‘bumps’ on the flippers of humpbacks is a wonderful example of how clever scientists pursuing interesting questions in animal locomotion can discover novel structures with practical applications in human technology,” said Richard Marsh of Northeastern University in Boston, Mass. of Fish’s work.

“The overall arching message is that we can look to various animals and we can start to see things we can transfer from the natural world into technologies,” Fish said. via. discovery

Popularity: 16% [?]