Passive propulsion in vortex wakes
Passive propulsion in vortex wakes
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DOI：
10.1017/s0022112005007925
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发表时间：
2006-02-25
影响因子：
3.7
通讯作者：
Lauder, GV
中科院分区：
文献类型：
--
作者：
Beal, DN;Hover, FS;Lauder, GV
当一条死鱼的柔韧性身体与一个钝形圆柱体的尾迹形成的迎面而来的涡流产生共鸣时，它就被推进了上游，尽管它远在圆柱体的吸力区域之外。在这种被动推进模式下，鱼的身体从迎面而来的涡流中提取足够的能量来产生推力来克服自身的阻力。在类似的湍流尾迹中，在钝形圆柱后面大致相同的距离处，被动安装的高展弦比箔片也显示出利用类似的流动能量提取机制推动自己上游。在这种情况下，在产生推力的同时，从流体中提取机械能。这些结果在实验上证明，在适当的条件下，一个物体可以在不消耗自身任何能量的情况下，在一定距离上跟随甚至赶上上游的另一个物体。这一发现对于低阻力能量收集装置的开发，以及在流动水中和在尾流形成障碍后游泳的鱼类的能量学也具有重要意义。
A dead fish is propelled upstream when its flexible body resonates with oncoming vortices formed in the wake of a bluff cylinder, despite being well outside the suction region of the cylinder. Within this passive propulsion mode, the body of the fish extracts sufficient energy from the oncoming Vortices to develop thrust to overcome its own drag. In a similar turbulent wake and at roughly the same distance behind a bluff cylinder, a passively mounted high-aspect-ratio foil is also shown to propel itself upstream employing a similar flow energy extraction mechanism. In this case, mechanical energy is extracted from the flow at the same time that thrust is produced. These results prove experimentally that, under proper conditions, a body can follow at a distance or even catch up to another upstream body without expending any energy of its own. This observation is also significant in the development of low-drag energy harvesting devices, and in the energetics of fish dwelling in flowing water and swimming behind wake-forming obstacles.