Metachronal Swimming of Mantis Shrimp: Kinematics and Interpleopod Vortex Interactions
Metachronal Swimming of Mantis Shrimp: Kinematics and Interpleopod Vortex Interactions
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DOI：
10.1093/icb/icab052
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发表时间：
2021-05-16
影响因子：
2.6
通讯作者：
Murphy, David W.
中科院分区：
文献类型：
--
作者：
Garayev, Kuvvat;Murphy, David W.
螳螂虾通过后三角划水游泳，在这种模式下，腹足类(游肢)按顺序划水，从最后一对开始，然后是前邻居。不同的生物，包括纤毛虫、纤毛虫、桡足类、磷虾和龙虾，在不同的大小、雷诺数和推进比下也使用类似的游泳模式。理解这种类型的运动很重要，因为它很普遍，可能会启发对效率、健壮性和机动性有需求的水下机器人的设计。然而，对自由游动、按时间划船的生物体周围的流动的详细测量很少，特别是对于在高雷诺数区域(Re>；=10(4))游泳的生物体。在这项研究中，我们提出了一种游泳的孔雀螳螂虾(Odontodactylus Scyllarus)的时间分辨的平面PIV测量。对这只动物的运动学同步测量显示，平均游泳速度为0.2-1.9米S(-1)，节拍频率为3.6-13赫兹，对应的推进比为0.75-1.84，基于身体的雷诺数为23,000-217,000。此外，动物的笔划并不是纯粹的超时的，在第一次和第五次翼足类力量笔划开始之间有很长的相位滞后。矢状面上的流动测量表明，每对冲刷的翼足类动物都会产生一个向后移动的尖端涡流，以躲避其他翼足类动物的回收冲程的破坏。最前面的一对复足动物产生的涡旋最强，由于动物的高推进比，它被最后面的复足对的力量冲程所拦截。由于这种相互作用，涡旋强度增加，这可能会提高游泳速度或效率。提出了后翼足类截获涡旋的关系式，即相互作用的肋足类之间的相位滞后与拍频、肋足之间的距离以及涡旋相对于动物的速度有关。我们用一个新的参数来描述这种相互作用，这个参数被称为肋足间涡旋相位匹配Strouhal数StIVPM，它等于相互作用的肋足类之间的相位滞后。这个新的无量纲参数在预测其他物种或物理模型中可能发生建设性相互作用的条件时可能是有用的。最后，我们将推进比与雷诺数之比，即基于弹体的雷诺数与基于肋脚架的雷诺数之比联系起来。这些参数的重要性，促进了在这里确定的肋足类之间的涡旋相互作用，在动态规模的实验中，以及在学校的超时游泳者背后的尾迹信号中进行了讨论。
Mantis shrimp swim via metachronal rowing, a pattern in which the pleopods (swimming limbs) stroke sequentially, starting with the last pair and followed by anterior neighbors. A similar swimming pattern is used at various sizes, Reynolds numbers, and advance ratios by diverse organisms including ciliates, ctenophores, copepods, krill, and lobsters. Understanding this type of locomotion is important because it is widespread and may inspire the design of underwater vehicles where efficiency, robustness, and maneuverability are desired. However, detailed measurements of the flow around free-swimming, metachronally rowing organisms are scarce, especially for organisms swimming in a high Reynolds number regime (Re >= 10(4)). In this study, we present time-resolved, planar PIV measurements of a swimming peacock mantis shrimp (Odontodactylus scyllarus). Simultaneous kinematics measurements of the animal, which had body and pleopod lengths of 114 and 20mm, respectively, reveal mean swimming speeds of 0.2-1.9 m s(-1) and pleopod beat frequencies of 3.6-13Hz, corresponding to advance ratios of 0.75-1.84 and body-based Reynolds numbers of 23,000-217,000. Further, the animal's stroke is not purely metachronal, with a long phase lag between initiation of the first and fifth pleopod power strokes. Flow measurements in the sagittal plane show that each stroking pleopod pair creates a posteriorly moving tip vortex which evades destruction by the recovery strokes of other pleopod pairs. The vortex created by the anteriormost pleopod pair is the strongest and, owing to the animal's high advance ratio, is intercepted by the power stroke of the posteriormost pleopod pair. The vortex strength increases as a result of this interaction, which may increase swimming speed or efficiency. A relationship for vortex interception by the posterior pleopod is proposed that relates the phase lag between the interacting pleopods to the beat frequency, distance between those pleopods, and speed of the vortex relative to the animal. We describe this interaction with a novel parameter called the interpleopod vortex phase matching Strouhal number StIVPM which is equal to the phase lag between interacting pleopods. This new nondimensional parameter may be useful in predicting the conditions where a constructive interaction may occur in other species or in physical models. Finally, we relate the advance ratio to the Reynolds number ratio, the ratio between the body-based Reynolds number and the pleopod-based Reynolds number. The importance of these parameters in promoting the interpleopod vortex interactions identified here, in dynamically scaled experiments, and in wake signatures behind schooling metachronal swimmers is discussed.