Shark Skin Boundary Layer Control
An investigation into the separation control mechanisms found on the skin of fast-swimming sharks, with a particular focus on the shortfin mako (Isurus oxyrinchus) which is considered to be one of the fastest pelagic shark species, was carried out. Previous researchers have reported a bristling capability of the scales, or denticles, in certain species of sharks. This study identified that bristling angle is highly dependent on body location, with some scales easily erectable to angles in excess of 50∘. The flexibility of the scale appears to be due to a reduction in the size of the base of the scale where anchored into the skin. It is hypothesized that the scales act as a passive, flow-actuated mechanism as a means of controlling flow separation.
Key wordsShark skin flow separation drag reduction
Funding for this work received through collaborative NSF grants (0932352, 0744670 and 0931787) to A. Lang, P. Motta, and R. Hueter to support both the engineering and biological work is gratefully acknowledged. We also thank Jessica Davis for assisting in the shark measurements and Candy Miranda for preparing the histological samples. We also thank Edward Haller for assistance with acquiring the SEM shark skin images. Finally, we wish to express our gratitude to Paul and Jane Majeski and crew, Captain Mark Sampson, Captain Al VanWormer, Philip Pegley, Jack Morris, and Mote Marine Laboratory for providing shark specimens; and to Lisa Natanson for her aid as well in obtaining specimens.
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