Variations in vortex structure with changes in swimming velocity during human underwater undulatory swimming

IF 2.3 3区工程技术 Q2 ENGINEERING, MECHANICAL Experiments in Fluids Pub Date : 2025-01-11 DOI:10.1007/s00348-025-03955-9

Yusaku Nakazono, Hirofumi Shimojo, Jun Sakakibara, Yasuo Sengoku, Hideki Takagi, Takaaki Tsunokawa

{"title":"Variations in vortex structure with changes in swimming velocity during human underwater undulatory swimming","authors":"Yusaku Nakazono, Hirofumi Shimojo, Jun Sakakibara, Yasuo Sengoku, Hideki Takagi, Takaaki Tsunokawa","doi":"10.1007/s00348-025-03955-9","DOIUrl":null,"url":null,"abstract":"<div>Vortices generated during underwater undulatory swimming (UUS) produced thrust and propelled swimmers. Therefore, clarifying how the vortices generated during UUS changed with different swimming velocities was crucial for improving swimming performance. This study aimed to clarify the changes in vortex structure in UUS when test flow velocities (U) were varied. A male collegiate swimmer participated in the trials, and trial swims were performed at three different U (0.8, 1.0, and 1.2 m/s). Particle image velocimetry (PIV) was used to analyze the flow fields behind the swimmer. The flow field was converted into a quasi-three-dimensional flow by performing multiple trials at the same U and averaging the results. The peak value of the vorticity component in the flow field increased with U. The structure of the vortices observed from the end of a down-kick to the beginning of an up-kick changed as U increased, and the direction of the jet flow between the vortex pairs became vertically downward. This phenomenon resembled the C-start maneuver seen in fish, where sudden acceleration prompted a more vertical downward flow direction. Such a change in vortex structure was considered to be a strategy to generate large momentum during an up-kick. This was the first study to quantify the vortex structure during UUS and reveal the variations in vortex structure with changes in swimming velocities, highlighting the importance of the down-kick to up-kick switching phase in UUS from the vortex structure in the flow field perspective.</div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"66 2","pages":""},"PeriodicalIF":2.3000,"publicationDate":"2025-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Experiments in Fluids","FirstCategoryId":"5","ListUrlMain":"https://link.springer.com/article/10.1007/s00348-025-03955-9","RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ENGINEERING, MECHANICAL","Score":null,"Total":0}

引用次数: 0

Abstract

Vortices generated during underwater undulatory swimming (UUS) produced thrust and propelled swimmers. Therefore, clarifying how the vortices generated during UUS changed with different swimming velocities was crucial for improving swimming performance. This study aimed to clarify the changes in vortex structure in UUS when test flow velocities (U) were varied. A male collegiate swimmer participated in the trials, and trial swims were performed at three different U (0.8, 1.0, and 1.2 m/s). Particle image velocimetry (PIV) was used to analyze the flow fields behind the swimmer. The flow field was converted into a quasi-three-dimensional flow by performing multiple trials at the same U and averaging the results. The peak value of the vorticity component in the flow field increased with U. The structure of the vortices observed from the end of a down-kick to the beginning of an up-kick changed as U increased, and the direction of the jet flow between the vortex pairs became vertically downward. This phenomenon resembled the C-start maneuver seen in fish, where sudden acceleration prompted a more vertical downward flow direction. Such a change in vortex structure was considered to be a strategy to generate large momentum during an up-kick. This was the first study to quantify the vortex structure during UUS and reveal the variations in vortex structure with changes in swimming velocities, highlighting the importance of the down-kick to up-kick switching phase in UUS from the vortex structure in the flow field perspective.

查看原文

微信好友朋友圈 QQ好友复制链接

本刊更多论文

人类水下波动游泳时旋涡结构随游泳速度的变化

水下波动游泳（UUS）过程中产生的涡流产生推力并推动游泳者。因此，弄清UUS过程中产生的涡如何随着游泳速度的不同而变化，对于提高游泳成绩至关重要。本研究旨在阐明当试验流速(U)变化时UUS内涡结构的变化。一名男子大学游泳运动员参加了试验，试验游泳以三种不同的U（0.8, 1.0和1.2 m/s）进行。采用粒子图像测速技术（PIV）对游泳者身后的流场进行了分析。在同一U下进行多次试验并取平均，将流场转化为准三维流场。流场涡度分量的峰值随U的增大而增大，从下踢结束到上踢开始的涡结构随U的增大而变化，涡对之间的射流方向垂直向下。这种现象类似于在鱼身上看到的c型启动动作，突然的加速促使水流的方向更垂直向下。涡结构的这种变化被认为是在上踢过程中产生大动量的一种策略。本研究首次量化了UUS过程中的涡结构，揭示了涡结构随游泳速度变化的变化，从流场的涡结构角度强调了UUS中下踢到上踢转换阶段的重要性。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

求助全文

约1分钟内获得全文去求助

来源期刊

Experiments in Fluids 工程技术-工程：机械

CiteScore

5.10

自引率

12.50%

发文量

157

审稿时长

3.8 months

期刊介绍： Experiments in Fluids examines the advancement, extension, and improvement of new techniques of flow measurement. The journal also publishes contributions that employ existing experimental techniques to gain an understanding of the underlying flow physics in the areas of turbulence, aerodynamics, hydrodynamics, convective heat transfer, combustion, turbomachinery, multi-phase flows, and chemical, biological and geological flows. In addition, readers will find papers that report on investigations combining experimental and analytical/numerical approaches.