Hydrodynamic flow control in marine mammals

Abstract

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.

Sink and swim: kinematic evidence for lifting-body mechanisms in negatively buoyant electric rays Narcine brasiliensis

“…More generally, hydrodynamic flow control is essential in allowing marine mammals to maneuver (Fish et al, 2003;Fish et al, 2008). Unlike marine mammals, however, electric rays do not swim or accelerate rapidly.…”

Turning performance in squid and cuttlefish: unique dual mode, muscular hydrostatic systems

“…Many studies on aquatic locomotion have focused on steady rectilinear swimming of fishes (Bartol et al, 2008;Blake et al, 1995;Blake, 1991, 1997;Lauder, 1999, 2000;Gray, 1933;Harper and Blake, 1990;Kasapi et al, 1993;Liao et al, 2003;Maia and Wilga, 2013;Webb, 1975Webb, , 1978Webb, , 1983Wilga and Lauder, 2000), cephalopods (Anderson and Grosenbaugh, 2005;Bartol et al, 2001aBartol et al, ,b, 2008Bartol et al, , 2009aBartol et al, ,b, 2016O'Dor, 1988;Stewart et al, 2010;Wells and O'Dor, 1991) and marine mammals (Fish, 1993(Fish, , 1994Fish et al, 2008). Although these studies have provided valuable information on swimming performance, much less is known about unsteady and intermittent swimming movements.…”

Effects of added drag on cetaceans : fishing gear entanglement and external tag attachment

“…Body shape changes with age and growth affect the ratio of body length to width, affecting the body's overall streamlining (see e.g. Appendix E3, Chapter 6; Woodward, 2006;Fish et al, 2008).…”

“…These changes in girth are most pronounced mid-body, affecting the position of maximal thickness and therefore the streamlined body shape (Blake, 1983;Fish et al, 2008). Significantly thicker blubber (Dunkin et al, 2005) and decreased body density (Dunkin et al, 2010) have been measured during pregnancy, though effect relative to the weight of the fetus is uncertain.…”