Hydrodynamic Flow Control in Marine Mammals

• Main Authors: Fish, Frank E, Howle, Laurens E, Murray, Mark M
• Other Authors: NAVAL ACADEMY ANNAPOLIS MD DEPT OF MECHANICAL ENGINEERING
• Format: Text
• Language: English
• Published: 2008
• Subjects: Biological Oceanography; Fluid Mechanics; Bionics; *AQUATIC ANIMALS; *BIOMIMETICS; *FLIPPERS; *HYDRODYNAMICS; *LEADING EDGES; ANGLE OF ATTACK; CONTROL; FLOW FIELDS; LIFT; MAMMALS; MANEUVERABILITY; MORPHOLOGY(BIOLOGY); NAVIER STOKES EQUATIONS; REYNOLDS NUMBER; STALLING; SURFACES; SWIMMING; UNDERWATER PROPULSION; WIND TUNNEL TESTS; *HYDRODYNAMIC FLOW CONTROL; *MARINE MAMMALS; *FLUKES; PECTORAL FLIPPERS; LEADING EDGE MODIFICATION; TUBERCLES; FLEXIBLE PROPULSORS; VIBRISSAE; BUMPY SURFACES; RANS(REYNOLDS-AVERAGED NAVIER-STOKES); Megaptera novaeangliae
• Online Access: http://www.dtic.mil/docs/citations/ADA594181; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA594181

The ability to control the flow of water around the body dictates the performance of marine mammals in the aquatic environment. Morphological specializations of marine mammals afford mechanisms for passive flow control. Aside from the design of the body, which minimizes drag, the morphology of the appendages provides hydrodynamic advantages with respect to drag, lift, thrust, and stall. The flukes of cetaceans and sirenians and flippers of pinnipeds possess geometries with flexibility, which enhance thrust production for high efficiency swimming. The pectoral flippers provide hydrodynamic lift for maneuvering. The design of the flippers is constrained by performance associated with stall. Delay of stall can be accomplished passively by modification of the flipper leading edge. Such a design is exhibited by the leading edge tubercles on the flippers of humpback whales (Megaptera novaeangliae). These novel morphological structures induce a spanwise flow field of separated vortices alternating with regions of accelerated flow. The coupled flow regions maintain areas of attached flow and delay stall to high angles of attack. The delay of stall permits enhanced turning performance with respect to both agility and maneuverability. The morphological features of marine mammals for flow control can be utilized in the biomimetic design of engineered structures for increased power production and increased efficiency. Published in Integrative and Comparative Biology, 6 May 2008. Prepared in cooperation with the Department of Biology, West Chester University, West Chester, PA, and the Mechanical Engineering and Material Science Department and Center for Nonlinear and Complex Systems, Duke University, Durham, NC. Sponsored in part by DARPA.