[PSUBS-MAILIST] FYI-Dolphin skin

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FLOW CONTROL BY MEANS OF DOLPHIN SKIN
AND ITS ARTIFICIAL ANALOGUES
Peter W. Carpenter and Reza Ali
Fluid Dynamics Research Centre, University of Warwick, Coventry, CV4 7AL
Surprisingly there is not really complete agreement on the details of the structure of
the dolphin’s epidermis and dermis. There is even less agreement concerning the
hydrodynamic significance or function of some of the features found in dolphin skin.
We shall review the evidence concerning the structure of the skin and describe some
of our research on the hydrodynamics of dolphin skin [1,2]. Of particular interest is
the potential laminar-flow properties of dolphin skin. Amongst other things we will
report on our recent work that reveals for the first time the advantageous
hydrodynamic effect of the cutaneous ridges (or microscales) seen as small-amplitude
transverse waves on the outer surface of dolphin skin [3,4].
Interest in artificial analogues of the dolphin epidermis originates with the compliant
coatings designed and tested by Kramer [5]. The laminar-flow properties of Kramer’s
coatings were confirmed theoretically by using our theoretical model of the coatings
[6]. This body of theory has been confirmed by detailed experimental studies [1] that
will be briefly described. Interestingly, the work on artificial analogues of the
dolphin epidermis can even provide information for the laminar-flow properties of the
dolphin itself. This work will also be described.
(1) Carpenter, P.W., Davies, C. and Lucey, A.D., Hydrodynamics and compliant
walls. Does the dolphin have a secret?, Current Science 79, 758-765, (2000)
(2) Babenko, V.V. and Carpenter, P.W., Dolphin hydrodynamics, In Flow in
collapsible tubes and past highly compliant boundaries, (eds. P.W. Carpenter &
T.J. Pedley), Kluwer, pp. 13.1-13.31, (2002).
(3) Ridgway, S.H. and Carder, D.A., Features of dolphin skin with potential
hydrodynamic importance, IEEE Eng. Med. Biol. 12, 83-88, (1993).
(4) Babenko, V.V., Gnitetskii, N.A. and Kozlov, L.F., Preliminary outcomes of
research on the elastic properties of the skin of live dolphins, (in Russian), Bionika
3, 12-19, (1969).
(5) Kramer, M.O., Boundary layer stabilization by distributed damping, J. Aero. Sci
24, 459, (1957), J. Amer. Soc. Naval Eng. 72, 25-33, (1960).
(6) Carpenter, P.W. and Garrad, A.D., The hydrodynamic stability of the flow over
Kramer-type compliant surfaces, J. Fluid Mech. 155, 465-510, (1985).