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Hydrodynamic aspects of shark scalesRidge morphometrices on placoid scales from 12 galeoid shark species were examined in order to evaluate their potential value for frictional drag reduction. The geometry of the shark scales is similar to longitudinal grooved surfaces (riblets) that have been previously shown to give 8 percent skin-friction reduction for turbulent boundary layers. The present study of the shark scales was undertaken to determine if the physical dimensions of the ridges on the shark scales are of the right magnitude to be used by the sharks for drag reduction based on previous riblet work. The results indicate that the ridge heights and spacings are normally maintained between the predicted optimal values proposed for voluntary and burst swimming speeds throughout the individual's ontogeny. Moreover, the species which might be considered to be the faster posses smaller and more closely spaced ridges that based on the riblet work would suggest a greater frictional drag reduction value at the high swimming speeds, as compared to their more sluggish counterparts.
Document ID
19860013418
Document Type
Contractor Report (CR)
Authors
Raschi, W. G. (Bucknell Univ. Lewisburg, PA, United States)
Musick, J. A. (Coll. of William and Mary Gloucester Point, Va., United States)
Date Acquired
September 5, 2013
Publication Date
March 1, 1986
Subject Category
FLUID MECHANICS AND HEAT TRANSFER
Report/Patent Number
NAS 1.26:3963
NASA-CR-3963
Funding Number(s)
PROJECT: RTOP 505-31-13
CONTRACT_GRANT: NAS1-16042
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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