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Skin reduces drag: shark

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Shark / Albert Kok / LicenseCC-by-nc-sa - Attribution Non-commercial Share Alike

The skin of sharks reduces drag by having a scales with longitudinal grooves.

BIOMIMICRY TAXONOMY
Summary
While a shark’s coarse shape is famously hydrodynamic, shark skin is anything but smooth. The very small individual scales of shark skin, called dermal denticles ("little skin teeth"), are ribbed with longitudinal grooves which result in water moving more efficiently over their surface than it would were shark scales completely featureless. Over smooth surfaces, fast-moving water begins to break up into turbulent vortices, or eddies, in part because the water flowing at the surface of an object moves slower than water flowing further away from the object. This difference in water speed causes the faster water to get "tripped up" by the adjacent layer of slower water flowing around an object, just as upstream swirls form along riverbanks. The grooves in a shark’s scales simultaneously reduce eddy formation in a surprising number of ways: (1) the grooves reinforce the direction of flow by channeling it, (2) they speed up the slower water at the shark’s surface (as the same volume of water going through a narrower channel increases in speed), reducing the difference in speed of this surface flow and the water just beyond the shark’s surface, (3) conversely, they pull faster water towards the shark’s surface so that it mixes with the slower water, reducing this speed differential, and finally, (4) they divide up the sheet of water flowing over the shark’s surface so that any turbulence created results in smaller, rather than larger, vortices. (Courtesy of The Biomimicry Institute)
About the inspiring organism
Med_4212137785_51218554bc_b Sphyrna
Sphyrna

Learn more at EOL.org
Organism/taxonomy data provided by:
Species 2000 & ITIS Catalogue of Life: 2008 Annual Checklist


Bioinspired products and application ideas

Application Ideas: Decrease fuel consumption in water craft, increase performance in swimsuits, reduce friction inside pipes.

Industrial Sector(s) interested in this strategy: Transportation, manufacturing



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