1 School of Naval Architecture and Ocean Engineering, Jiangsu University of Science and Technology , Zhenjiang, Jiangsu 212003 , People's Republic of China.
2 Department of Naval Architecture, Ocean and Marine Engineering, University of Strathclyde , Glasgow G4 0LZ , UK.
J R Soc Interface. 2019 Jan 31;16(150):20180768. doi: 10.1098/rsif.2018.0768.
This study focuses on the hydrodynamic interaction between two or three human swimmers in competitive swimming. Although the swimming performance of a single swimmer has been widely examined, studies on the interaction between multiple competitive swimmers are very rare. Experiments showed evidence that the drag of a swimmer could be modified by the existence of the other adjacent competitors (Chatard & Wilson. 2003 Med. Sci. Sports Exerc. 35, 1176-1181. ( doi:10.1249/01.MSS.0000074564.06106.1F )). The following questions arise: (1) what mechanism determines the interaction; (2) which position experiences drag reduction or drag increase; (3) how much can drag be reduced or increased in a formation? According to the authors' knowledge, such questions have not been addressed by any published literature. Therefore, the main purpose of this study is to find the mechanism of the hydrodynamic interaction between human swimmers and to quantify this interactive effect by using a steady potential flow solver. The free-surface effect was fully taken into account in our calculations. We firstly calculated the wave drag of a swimmer swimming solely in an open swimming pool. Then we calculated the wave drag of the same swimmer when he/she swam in the wake region of one or two leading swimmers. The results showed that the hydrodynamic interaction made a significant contribution to the drafter's wave drag. By following a leading swimmer, a drafter at wave-riding positions could save up to 63% of their wave drag at speed of 2.0 m s and lateral separation of 2.0 m. Particularly, when a drafter is following two side-by-side leaders, the drag reduction could even be doubled. To the authors' knowledge, this study is the first to demonstrate that the hydrodynamic interaction between human swimmers can best be described and explained in terms of wave interference effect on the free water surface. When the wave cancellation effect is observed, the wave drag of a drafter could be minimized, and this wave cancellation effect can be achieved only when the drafter is in a wave-riding position.
本研究关注于竞技游泳中两名或三名人类游泳者之间的水动力相互作用。尽管单个游泳者的游泳性能已被广泛研究，但对多个竞技游泳者相互作用的研究却非常罕见。实验表明，游泳者的阻力可以通过其他相邻竞争者的存在而改变（Chatard & Wilson. 2003 Med. Sci. Sports Exerc. 35, 1176-1181. (doi:10.1249/01.MSS.0000074564.06106.1F)）。由此产生了以下问题：（1）什么机制决定了相互作用；（2）哪个位置会减少或增加阻力；（3）在一个编队中可以减少或增加多少阻力？据作者所知，没有任何已发表的文献探讨过这些问题。因此，本研究的主要目的是找到人类游泳者之间水动力相互作用的机制，并通过使用稳态势流求解器来量化这种相互作用效应。在我们的计算中充分考虑了自由表面效应。我们首先计算了仅在开放游泳池中游泳的游泳者的波浪阻力。然后，我们计算了同一游泳者在一个或两个领先游泳者的尾流区域中游泳时的波浪阻力。结果表明，水动力相互作用对拖动者的波浪阻力有显著贡献。跟随一个领先的游泳者，在波峰位置的拖动者在速度为 2.0 m s 和 2.0 m 的侧向分离时可以节省高达 63%的波浪阻力。特别是，当拖动者跟随两个并排的领先者时，阻力的减少甚至可以翻倍。据作者所知，这项研究首次表明，人类游泳者之间的水动力相互作用可以最好地用自由水面上的波干扰效应来描述和解释。当观察到波抵消效应时，拖动者的波浪阻力可以最小化，并且只有当拖动者处于波峰位置时才能实现这种波抵消效应。
