Dolphin skin key to subaquatic speed

Flipper fights 'form drag'

Dolphin skin will be key in future designs of marine vessels, thanks to Japanese research.

Fortunately, this does not spell the end for the sea-going mammals: physicists at the Kyoto Institute of Technology have discovered how the surface of a dolphin's skin reduces drag as it swims, and the findings will help scientists to design more energy-efficient boats and submarines.

The research team wanted to find out what role the dolphin's skin played in reducing 'form drag' - the pressure of water against the skin. Dolphins have extremely soft, flaky skin which they shed every two hours. By modelling how the water flows over the flakes, and how they are eventually shed, the research team was able to conclude that the softness of the skin does reduce friction.

Professor Yoshimichi Hagiwara and colleagues also discovered that as the skin flakes off, it also helps the dolphin through the water: the flakes break up swirling vortices next to the skin that would otherwise slow the animal down.

Professor Hagiwara explains that travelling quickly through water is much more complex than travelling quickly through air. He and his team are now building simulation dolphins to replicate the 'flaking' that allows them to move so fast through water. "This research could help us build boats, ocean liners and submarines using technology based on these natural solutions," he said.

The original paper was published in the Institute of Physics journal, Journal of Turbulence. ®

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