Anomalous hydrodynamic drafting of interacting flapping flags.
Anomalous hydrodynamic drafting of interacting flapping flags.
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DOI：
10.1103/physrevlett.101.194502
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发表时间：
2008-11
影响因子：
8.6
通讯作者：
Leif Ristroph;Jun Zhang
中科院分区：
文献类型：
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作者：
Leif Ristroph;Jun Zhang
在流体中移动的物体聚集体中，引导者下游的物体通常会受到较小的阻力。这种传统的绘图适用于固定形状的物体，但人们对流动中可变形物体的相互作用知之甚少，就像鱼群一样。在我们关于“学校教育”飘扬旗帜的实验中，我们发现，团体的领导者享有显着的阻力减少（高达 50%），而下游旗帜则遭受阻力增加。通过剖析形状和流动在确定阻力时的相互影响，可以合理化这种违反直觉的倒置阻力关系。刚体从未观察到反向绘图，这显然是由于刚体无法响应相邻流场的变化而变形。
In aggregates of objects moving through a fluid, bodies downstream of a leader generally experience reduced drag force. This conventional drafting holds for objects of fixed shape, but interactions of deformable bodies in a flow are poorly understood, as in schools of fish. In our experiments on "schooling" flapping flags, we find that it is the leader of a group who enjoys a significant drag reduction (of up to 50%), while the downstream flag suffers a drag increase. This counterintuitive inverted drag relationship is rationalized by dissecting the mutual influence of shape and flow in determining drag. Inverted drafting has never been observed with rigid bodies, apparently due to the inability to deform in response to the altered flow field of neighbors.