*Department of Biology, West Chester University, West Chester, PA 19383, USA; Mechanical Engineering and Material Science Department and Center for Nonlinear and Complex Systems, Duke University, Durham, NC 27708-0300, USA; Mechanical Engineering Department, United States Naval Academy, Annapolis, MD 21402, USA.
Integr Comp Biol. 2008 Dec;48(6):788-800. doi: 10.1093/icb/icn029. Epub 2008 May 6.
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.
控制水流围绕身体的能力决定了海洋哺乳动物在水生环境中的表现。海洋哺乳动物的形态特化提供了被动流动控制的机制。除了设计最小化阻力的身体外，附肢的形态提供了关于阻力、升力、推力和失速的水动力优势。鲸类和海牛的尾鳍和鳍足类动物的鳍状肢具有柔韧性的几何形状，增强了高效游泳的推力产生。胸鳍提供操纵的水动力升力。鳍状肢的设计受到与失速相关的性能的限制。通过对翼梢前缘的修改，可以被动地延迟失速。这种设计在座头鲸（Megaptera novaeangliae）的鳍状肢前缘的瘤突上得到了体现。这些新颖的形态结构诱导了一个展向流场，其中分离的涡旋与加速流区交替出现。耦合的流区保持附着流区并延迟失速至高攻角。失速的延迟允许在敏捷性和机动性方面提高转弯性能。海洋哺乳动物的流动控制形态特征可用于仿生设计工程结构，以提高功率输出和效率。
