How the bending kinematics of swimming lampreys build negative pressure fields for suction thrust
How the bending kinematics of swimming lampreys build negative pressure fields for suction thrust
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DOI：
10.1242/jeb.144642
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发表时间：
2016-12-15
影响因子：
2.8
通讯作者：
Colin, Sean P.
中科院分区：
文献类型：
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作者：
Gemmell, Brad J.;Fogerson, Stephanie M.;Colin, Sean P.
游泳动物通常会弯曲身体以产生推力。像鳗鱼和七鳃鳗这样的波浪形动物，它们的身体弯曲成波浪形，从头部到尾部。这些运动学加速了邻近流体的流动，从而以产生推力的方式改变了压力场。我们使用了一种比较的方法来评估在这个过程中的因果关系，通过量化的流体动力学效应的身体运动学在身体流体界面的七鳃鳗，海岩鳅，在稳态游泳。我们比较了运动学和流体动力学的健康控制七鳃鳗，七鳃鳗的脊髓已被横断的中段，导致被动运动学沿着他们的身体的后半部分。使用高速粒子图像测速仪（PIV）和method量化压力场，我们详细介绍了如何控制七鳃鳗的主动弯曲运动学是至关重要的建立强大的负压场（相对于环境场），产生高推力的地区在弯曲，因为他们所有的沿着身体。被横切的七鳃鳗的被动运动学只能在尾部产生显著的推力，依赖于正压场。这些不同的压力和推力情景是由于主动体波与被动体波如何产生和控制涡量的差异。这说明了为什么波浪形七鳃鳗在流体中拉而不是推更有效。
Swimming animals commonly bend their bodies to generate thrust. For undulating animals such as eels and lampreys, their bodies bend in the form of waves that travel fromhead to tail. These kinematics accelerate the flow of adjacent fluids, which alters the pressure field in a manner that generates thrust. We used a comparative approach to evaluate the cause-and-effect relationships in this process by quantifying the hydrodynamic effects of body kinematics at the body-fluid interface of the lamprey, Petromyzon marinus, during steady-state swimming. We compared the kinematics and hydrodynamics of healthy control lampreys to lampreys whose spinal cord had been transected midbody, resulting in passive kinematics along the posterior half of their body. Using high-speed particle image velocimetry (PIV) and amethod for quantifying pressure fields, we detail how the active bending kinematics of the control lampreys were crucial for setting up strong negative pressure fields (relative to ambient fields) that generated highthrust regions at the bends as they traveled all along the body. The passive kinematics of the transected lamprey were only able to generate significant thrust at the tail, relying on positive pressure fields. These different pressure and thrust scenarios are due to differences in how active versus passive body waves generated and controlled vorticity. This demonstrates why it is more effective for undulating lampreys to pull, rather than push, themselves through the fluid.