Ogunka Uchenna E, Daghooghi Mohsen, Akbarzadeh Amir M, Borazjani Iman
J. Mike Walker '66 Department of Mechanical Engineering, Texas A&M University, College Station, TX 77843, USA.
Mechanical Engineering Program, University of Houston-Clear Lake, Houston, TX 77058, USA.
Biomimetics (Basel). 2020 Mar 3;5(1):9. doi: 10.3390/biomimetics5010009.
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 () from the ground creating a gap of 0 . 04 L . 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 . 04 L 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.
一些鳗形游泳者，如鳗鱼和七鳃鳗，在靠近水底的地方游动，据推测这具有流体动力学上的优势。为了研究在靠近水底游动是否具有流体动力学优势，对一个自行推进的鳗形游泳者进行了两次大涡模拟——一次是在远离水底的地方游动（自由游动），另一次是在靠近水底的地方游动，即中线距离水底为鱼体长度（L）的0.07，形成0.04L的间隙。模拟在相似条件下进行，两条鱼均从静止的水流中开始游动，最终达到稳定游动（恒定平均速度）。数值结果表明，在稳定游动期间，两个游泳者的速度、功耗、效率和尾流结构相似。这表明，当没有来流时，在距离水底大于0.04L的间隙处靠近水底游动并不能提高鳗形游泳者的游动性能，也就是说，尾流与水底的相互作用并不能提高游动性能。然而，当有来流时，靠近水底游动可能会有帮助，因为靠近水底的水流速度较低。
