MAE SEMINAR SERIES

 Wednesday, April 12, 2006, 1pm
Phillips Hall 7^th Floor Conference Room, #736

Optimization of energy by whales and dolphins requires adaptations that reduce drag, and improve thrust production and efficiency.  The control of flow over and around the body of whales, therefore, is critical to efficient swimming performance. Drag is minimized by streamlining of the body and appendages. These highly derived aquatic mammals have body shapes close to the optimal hydrodynamic design for drag reduction. Oscillations of the flukes, which are caudal hydrofoils, generate thrust throughout the stroke cycle and maintain a propulsive efficiency over 80%. This high efficiency is dependent on the passive, self-adjusting spanwise and chordwise bending of the flukes. Variation in body design also affects stability and turning performance. Major features affecting maneuverability are positions of control surfaces and flexibility of the body. Position of control surfaces provides a generally stable design with respect to an arrow model. Whales with flexible bodies and mobile flippers are able to turn tightly at low turning rates, whereas fast-swimming whales with less flexibility and relatively immobile flippers sacrifice small turn radii for higher turning rates. The humpback whale (Megaptera novaeangliae) is exceptional among the baleen whales in its ability to undertake acrobatic underwater maneuvers to catch prey.  In order to execute these maneuvers, such as banking and turning, humpback whales utilize extremely mobile, wing-like flippers. The humpback whale flipper is unique because of the presence of large tubercles along the leading edge, which gives this surface a scalloped appearance. The position, size and number of tubercles suggest analogues with specialized leading edge control devices associated with improvements in hydrodynamic performance on lifting surfaces. The tubercles function to produce vortical flows over the surface of the flipper and control lift characteristics at high angles of attack, where stall would occur. The morphologies displayed by animal species represent compromises between structural materials, evolutionary constraints, and diverse functional requirements. However, due to the high level of performance engendered by the various morphological solutions displayed in whales, these biological designs are of particular interest for the potential development of new and superior technological designs.

Dr. Frank Fish is a Professor of Biology at West Chester University of Pennsylvania, where he has been on the faculty since 1980.  He received a B.A. in Biology from SUNY Oswego in 1975.  He completed a M.Sc. in 1977 and a Ph.D. in 1980 from the Zoology Department of Michigan State University. Dr. Fish has published over 70 research articles, government reports, patents, and book chapters. He has served as chairperson of his department and was the chairperson of the Division of Vertebrate Morphology of the Society for Integrative and Comparative Biology. Dr. Fish's research is focused on the energetics and hydrodynamics of aquatic locomotion by vertebrates. Recent projects have included examinations of the evolution of swimming modes in aquatic mammals, energetics and maneuverability of marine mammals, hydrodynamic design of biological control surfaces, and energy conservation by formation movement.  Dr. Fish has appeared on the PBS series Evolution, and he has appeared in the BBC production Walking with Prehistoric Beasts, which was broadcast on the Discovery Channel.