Millions of years of evolution have maximized the efficiency of how sea creatures move through water while humans have been trying to perfect streamlined designs for barely a century - but we're catching up.

Biologists and engineers from across the U.S. have been studying the flippers, fins and tails of whales and dolphins and discovered some features of their structure that contradict long-held engineering theories.

Dr. Frank Fish of West Chester University will talk about the impact these discoveries may have on traditional industrial designs on Tuesday 8th July at the Society for Experimental Biology's Annual Meeting in Marseille [Session A2].



Large vortices are formed behind the troughs along the leading edge whereas flow behind the tubercles forms straight streamlines. The effect of these flow patterns induced by the tubercles is to delay stall. Credit: E. Paterson

Some of his observations are already being applied to real life engineering problems in a field known as biomimetics. The shape of whale flippers with one bumpy edge has inspired the creation of a completely novel design for wind turbine blades. This design has been shown to be more efficient and also quieter, but defies traditional engineering theories.

"Engineers have previously tried to ensure steady flow patterns on rigid and simple lifting surfaces, such as wings. The lesson from biomimicry is that unsteady flow and complex shapes can increase lift, reduce drag and delay 'stall', a dramatic and abrupt loss of lift, beyond what existing engineered systems can accomplish," Dr Fish advises. "There are even possibilities that this technology could be applied to aeronautical designs such as helicopter blades in the future."

The work centers on studies of vortices, tornado-shaped water formations that develop in the wake of the animals.



The dolphin uses a high efficiency mechanism to generate large amounts of thrust by the action of its tail fins. Credit: E. Paterson

"In the case of the humpback whale, vortices formed from tubercles (bumps) on the front edge of flippers help to generate more lift without the occurrence of stall, as well as enhancing manoeuvrability and agility," explains Dr Fish. "In the case of the tails of dolphins, vortices are formed at the end of the up and down strokes. These vortices are involved in the production of a jet in the wake of the dolphin that produces high thrust. By regulating the production of the vortices, the dolphin can maximize its efficiency while swimming."

This work will be presented at 13.10pm on Tuesday 8th July at the Society for Experimental Biology's Annual Meeting (6th – 10th July 2008) at Parc Chanot, Marseille, France.

Funded by the US National Science Foundation and the US Office of Naval Research

Article: Fish, F. E., Howle, L. E. and Murray, M. M. 2008. Hydrodynamic flow control in marine mammals; Integrative and Comparative Biology 211: 1859-1867.