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'Wet-dog shake' beats a towel

'Wet-dog shake' beats a towel

Sat August 18, 2012 11:20am

DON'T curse your wet dog too loud next time it shakes itself all over you. It may soon make your dishwasher much more efficient.

High-speed video has been used to track the methods different animals dry themselves with - and the wet-dog shake comes out on top.

It can shed 70 per cent of the water on its coat in a fraction of a second.

The Georgia Institute of Technology study seeks to understand the physics behind how the dog sprays off water in order to improve washing machines, dryers, painting equipment and other devices.

"In the future, self-cleaning and self-drying may arise as an important capability for cameras and other equipment subject to wet or dusty conditions", says David Hu, assistant professor of mechanical engineering and biology.

It may even improve the ability of remote robotic space probes to shed accumulating dust.

A dog shakes to dry after a bath. A study has shown a dog can clear itself of 70 per cent of unwanted water within a second.

But don't think a quick shake will speed up drying off after a shower or a day at the beach.

The secret is in the loose skin that mammals with fur tend to have, the study published in the Interface Journal of The Royal Society says.

This loose fat and skin "whips" around the body as the animal changes direction, increasing acceleration.

It is the frequency of this "whipping" which is the key to effective water-shedding. And that frequency is different according to the size and weight of each animal, the study finds.

The larger the animal, the slower it shakes.

The wet-dog-shake technique may help improve everything from drying clothes through to keeping space probes clear of sand.

A mouse will shake its body back and forth 27 times per second, experiencing acceleration forces of up to 20 times gravity.

A bear, however, only shakes four times per second.

The research group will continue to study how animals interact with water. Future research will focus on how water interacts with otter and beaver hair.





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