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Biomimicry Clips: Whale Filters And Wings
Jeremy Faludi, 5 Feb 07
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Here are two novel uses of biomimicry for green design, both inspired by whales: one is for filtering water, the other is for making airplane wings more efficient.

The University of South Australia has invented a water filter that works like a whale's baleen. Baleen Filters require no pressurization (which is what normally causes filtration to use energy) and clean themselves (which avoids creating waste and needing maintenance). They have a good video of how the product works: basically, gunky water is poured out over a screen that is much bigger than the water stream; as the screen catches gunk (which blocks water flow), the water naturally flows over the gunked-up part of the screen to the nearest part of the screen that's still clean, so it still gets filtered; then every so often a power-sprayer comes along at an oblique angle, pushing the gunk collected on the screen away into a separate tank where it can build up without blocking the filter. The Baleen Filter can filter particles down to 25 microns without needing chemical treatment. The same principle might be used for air filtration as well, though it would be a good deal harder to do since air would diffuse much more than water in a device like this.

Also inspired by whales, but completely unrelated, are aerodynamic wings based on humpback whale fins. In 2004, Duke University described how they and researchers at West Chester and the U.S. Naval Academy found that the bumpy "tubercles" along the front edge of humpback whale pectoral fins cause them to be more efficient and effective than anything in use on today's airplanes. In wind tunnel tests they compared a bumpy flipper to one with no bumps, and found "the tubercle flipper exhibited nearly 8 percent better lift properties, and withstood stall at a 40 percent steeper wind angle. The team was particularly surprised to discover that the flipper with tubercles produced as much as 32 percent lower drag than the sleek flipper." It does not work like a golf ball's divots; somewhat the opposite. The bumps push air or water into little vortices instead of a single sheet passing over the fin, which keeps the flow more attached to the fin (as opposed to less, with a golf ball); hence the better stall angle. Airplanes with these bumps on their wings would not only use less fuel, they would be much safer and more maneuverable. And airplanes won't be the only beneficiaries; researcher Laurens Howle said it would also apply to propellers, helicopter rotors, and ship rudders.

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This is amazing stuff. It's almost a shame that it took this long to realize that a bumpy wing does, in fact, work better than a smooth one. Aircraft have been around for over a century, and whales have been around for slightly longer!

Maybe we need to add an "Evolution" function into computer-aided design software. The user would design their "ideal" building or vehicle, and begin the "Evolution" process. The computer would introduce random mutations to random areas of the design. The computer would then somehow evaluate the efficiency of the design in response to randomly-generated external events. Less efficient mutations would be discarded and more-efficient mutations would be included in the next generation. With today's computing technology, what would take hundreds of years of evolution could be compressed into minutes.

It seems like the greatest scientific advances are discovered by accident. Why not create at environment where those accidents are encouraged? I know computer simulation has become a staple in modern design, but could this design process truly be considered random?

Biomimicry is a great way to improve technology and make it more harmonious with the world. But why limit biomimicry to design FEATURES on products. Let's mimic the design PROCESS itself!

Anyone who questions the value of seemingly-wasteful science should read this article. In this case, studying a whale's fin will make aircraft able to fly at slower approach speeds to landing, making aircraft safer for EVERYBODY. Aerospace engineers have "perfected" the wing for over 100 years. They have, in truth, done a magnificent job. But a 32-percent reduction in drag is a LEAP that I doubt few engineers could have imagined (of course, I don't have the details, but 32% sounds incredible, and a 40% greater stall angle would have ENORMOUS implications on aircraft design).

This article is evidence for the idea of "Consilience." World Changing goes a long way towards consilience as well! Thanks for the GREAT post!

Posted by: David on 6 Feb 07

I think the article about bumpy flippers is really interesting regarding fluid flow over surfaces at low speeds, however should not be viewed as a major oversight by the aeronautical industry.

Yes the research does show increases in effciency of a wing type model when one adds bumps to its leading edge, but this test was only conducted at low air speed. A modern commercial aircraft spends a vast amount of flight time at near transonic speeds. I would suggest that a wing with bumps on its leading edge travelling at near the speed of sound would quite possibly cause shock waves to form somewhere on the surface of the wing around the bumps. Shock waves cause a massive amount of drag and also instability.

These are the kind of concerns that aircraft designers have to balance up in the design process of an aircraft. Some wing shapes work better at low speeds and some at high, near supersonic, speeds.

I would speculate that with current maufacturing methods and materials, a design that envolved bumps appearing on the leading edge of airfraft wings would not be cost-effective.

So just to give a slightly different light on the article, I don't think this use of biomimicry is the immediate amazing solution to the aeronautical industry that it may be suggesting, it is however interesting in its own right.

I do think the comment about posible software being created in the design world that could evolve a design by itself very exciting. I'm sure some research into this is being done somewhere. It does seem like a mammoth task to replicate nature itself in software, but one which could lead to unimaginable benefits for humankind.

Posted by: Tim Elliott on 12 Feb 07



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