Friday, February 24, 2012

Vision Systems Design: The Swimsuit Issue

Many popular magazines such as Sports Illustrated rely on publishing yearly issues dedicated to celebrating the predominantly female human form in swimsuits, a cunning wheeze that boosts circulation and sales.

For years I have been wondering how a magazine such as Vision Systems Design might possibly be able to justify covering such a subject to the same effect. And recently I discovered the answer to my prayers.

The solution, naturally enough, lies in writing numerous stories about particle image velocimetry, a technique that uses a laser to illuminate millions of reflective particles in water. When images of the same are then captured by high-speed cameras, they allow researchers to observe how the particles move around objects found in the water -- including, of course, folks wearing swimsuits.

Through the use of such equipment, researchers hope to be able to develop more high-tech swimsuits that would give athletes a competitive advantage by reducing the drag of the water around their bodies as they swim.

Now there's been quite a lot of research work performed in this area, predominantly at Leeds University (Leeds, UK), where a Speedo-sponsored team led by Professor Jeff Peakall has been engaged conducting tests to examine how efficiently different fabrics move through the water.

Most recently, the university team was commissioned by the swimwear company to assist in the development of its new FASTSKIN3 Racing System swimsuit and spent 18 months testing levels of "fabric drag."

In a statement to the press this month, Peakall said, "We're really excited because I think we've found out that some of the materials are appreciably faster than anything we've seen before, and I'm absolutely confident that this is going to be of great benefit to competitive swimmers."

Not everyone is so optimistic. Take George Lauder, the Henry Bryant Bigelow Professor of Ichthyology at Harvard University (Cambridge, MA, USA), for example. He argues that the notion that simply donning a different swimsuit -- like a Speedo FASTSKIN II suit, with a surface purportedly designed to mimic shark skin to gain an edge on the competition -- is almost completely misplaced.

Experiments conducted in Lauder's lab, and described in The Journal of Experimental Biology, reveal that, while sharks' sandpaper-like skin does allow the animals to swim faster and more efficiently, the surface of the high-tech swimsuits has no effect when it comes to reducing drag as swimmers move through the water.

Indeed, Lauder claims to have conclusively shown that the surface properties themselves, which the manufacturer has in the past claimed to be biomimetic, don't do anything for propulsion.

That's not to say that the suits as a whole do nothing to improve performance. Lauder also reasons that there are all sorts of effects at work that aren't due to the surface effects of the swimsuit.

"Swimmers who wear these suits are squeezed into them extremely tightly, so they are very streamlined. They're so tight that they could actually change the circulation (of the swimmer), and increase the venous return to the body, and they are tailored to make it easier to maintain proper posture even when tired. I'm convinced they work, but it's not because of the surface," he says.

All that remains to be seen now is whether my swimsuit column has done anything to improve the circulation of Vision Systems Design and boost its companion web site page views.

1. Flumes and lasers test elite sportswear
2. Skin deep

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