The Ground Effect in Anguilliform Swimming
The Ground Effect in Anguilliform Swimming
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DOI：
10.3390/biomimetics5010009
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发表时间：
2020-03-01
期刊：
影响因子：
4.5
通讯作者：
Borazjani, Iman
中科院分区：
文献类型：
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作者：
Ogunka, Uchenna E.;Daghooghi, Mohsen;Borazjani, Iman
一些鳗鱼和七鳃鳗等鳗鱼在靠近地面的地方游泳，这被认为具有水动力优势。为了研究近地面游泳是否具有流体动力学优势，对自航鳗鱼进行了两次大涡模拟——一次远离地面游泳（自由游泳），另一次靠近地面，即中线距地面 0.07 鱼长 (L) 处，产生 0.04L 的间隙。模拟是在类似的条件下进行的，两条鱼从静止的水流中开始静止，达到稳定的游动（恒定的平均速度）。数值结果表明，两名游泳运动员在稳定游泳时具有相似的速度、功耗、效率和尾流结构。这表明，在没有来流的情况下，接近地面间隙大于0.04L的游泳并不能提高鳗鱼的游泳性能，即尾流与地面的相互作用并不能提高游泳性能。然而，当有流入的水流时，靠近地面游泳可能会有所帮助，因为靠近地面的水流速度较低。
Some anguilliform swimmers such as eels and lampreys swim near the ground, which has been hypothesized to have hydrodynamic benefits. To investigate whether swimming near ground has hydrodynamics benefits, two large-eddy simulations of a self-propelled anguilliform swimmer are carried out-one swimming far away from the ground (free swimming) and the other near the ground, that is, midline at 0.07 of fish length (L) from the ground creating a gap of 0.04L. Simulations are carried out under similar conditions with both fish starting from rest in a quiescent flow and reaching steady swimming (constant average speed). The numerical results show that both swimmers have similar speed, power consumption, efficiency, and wake structure during steady swimming. This indicates that swimming near the ground with a gap larger than 0.04L does not improve the swimming performance of anguilliform swimmers when there is no incoming flow, that is, the interaction of the wake with the ground does not improve swimming performance. When there is incoming flow, however, swimming near the ground may help because the flow has lower velocities near the ground.