Why don't mackerels swim like eels? The role of form and kinematics on the hydrodynamics of undulatory swimming
Why don't mackerels swim like eels? The role of form and kinematics on the hydrodynamics of undulatory swimming
复制标题
为什么鲭鱼不像鳗鱼那样游泳？
DOI：
10.1063/1.3205869
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发表时间：
2009
影响因子：
4.6
通讯作者：
F. Sotiropoulos
中科院分区：
文献类型：
--
作者：
I. Borazjani;F. Sotiropoulos
我们对3D自行式虚拟游泳者鱼的平均线的运动是规定的，但前进的游泳速度是通过Borazjani等人的流固耦合(FSI)数值方法计算的[J.Comp.物理，227(16)，2008]。我们认为：1)在自然界中，鳗类游动(M-C)；2)鳗类游动(M-A)；3)鳗鱼类游动(E-A)；4)鳗鱼类游动(E-C)。具有相同体型的虚拟游泳运动员在相同的流体(固定粘度)和相同的尾拍频率下以不同的运动学(M-C对M-A和E-C对E-A)进行比赛。无论体型如何，在过渡状态下(Re=4000)，鳗型运动学赢得比赛，而在惯性状态(无粘性极限)，心血管运动学占上风。我们的结果支持这样的观点，即水动力学因素在鱼类形状和运动学的进化中起到了作用，因为在自然界中，在过渡状态下，鳗形运动学是首选的，而在惯性状态下，血管形运动学是首选的。结果还表明，鱼尾迹的三维结构(单列涡和双列涡)在很大程度上与身体形状和运动学无关，并支持我们之前的发现[J.Exp.比奥尔。211(10)2008]斯特劳哈尔数是关键的管理参数。
We carry out numerical simulations with 3D self-propelled virtual swimmers, a mackerel (M) and an eel (E), to elucidate the role of form (body shape) and kinematics carangiform (C) vs. anguilliform (A) on the hydrodynamics of undulatory swimming. The motion of the fish mean line is prescribed but the forward swimming speed is calculated via the fluid-structure interaction (FSI) numerical approach of Borazjani et al [J. Comp. Physics, 227(16), 2008]. We consider: 1) a mackerel swimming as mackerel do in nature (M-C); 2) a mackerel swimming with anguilliform kinematics (M-A); 3) an eel swimming as eels do (E-A); and 4) an eel swimming with carangiform kinematics (E-C). Virtual swimmers with the same body shape race each other with different kinematics (M-C vs. M-A and E-C vs. E-A) in the same fluid (fixed viscosity) and with the same tail beat frequency. Regardless of body shape, anguilliform kinematics win the race in the transitional regime (Re = 4000) while carangiform kinematics prevail in the inertial regime (Inviscid limit). Our results support the notion that hydrodynamic considerations have played a role in the evolution of fish shapes and kinematics since in nature anguilliform kinematics are preferred in the transitional regime while carangiform kinematics are preferred in the inertial regime. Out results also show that the 3D structure of fish wakes (single vs. double row vortices) is largely independent of body shape and kinematics and support our previous findings [J. Exp. Biol. 211(10) 2008] that the Strouhal number is the key governing parameter.