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Dolphin-kick swimming maximizes water-flow utilization with increasing speed

Date:
March 14, 2024
Source:
University of Tsukuba
Summary:
Researchers investigated the propulsion mechanism by visualizing water flow around a swimmer during underwater dolphin-kick swimming in a water channel via particle image velocimetry. Their findings revealed that swimmers can utilize water flow and vortexes more effectively as their speed increases.
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Researchers from University of Tsukuba investigated the propulsion mechanism by visualizing water flow around a swimmer during underwater dolphin-kick swimming in a water channel via particle image velocimetry. Their findings revealed that swimmers can utilize water flow and vortexes more effectively as their speed increases.

The swimming motion imparts momentum to water, a fluid, thereby generating a propulsive force. Thus, we can understand the propulsion mechanism by examining the water flow generated by a swimmer's motion. However, observing colorless, transparent water with the naked eye or a camera is challenging. To address this issue, researchers employed particle image velocimetry, a technique utilized in fluid dynamics, to visualize water-flow patterns. They investigated how water flow changes as swimmers change their speed while executing the dolphin-kick swimming technique. This investigation was conducted in an experimental circulating-water channel (a pool with flowing water).

The results revealed that the water-flow velocity increased with increasing swimming speed during the underwater dolphin-kick lower-limb action, generating a strong vortex during the kicking action. This phenomenon possibly contributes to the increased propulsive force. Additionally, recycling of the flow generated during the downward-kick phase was observed during the transition to the upward-kick phase, with the effect becoming more pronounced as the swimming speed increased. This study marks the first observation of water-flow changes during dolphin-kick swimming at varying speeds.

This study is expected to advance research on water flow, a critical topic in swimming research. It offers scientific evidence for instructors to adopt kick-swimming techniques.

This work was supported by Japan Science and Technology Agency, Grant Number 22 K19725.


Story Source:

Materials provided by University of Tsukuba. Note: Content may be edited for style and length.


Journal Reference:

  1. Yusaku Nakazono, Hirofumi Shimojo, Yasuo Sengoku, Hideki Takagi, Takaaki Tsunokawa. Impact of variations in swimming velocity on wake flow dynamics in human underwater undulatory swimming. Journal of Biomechanics, 2024; 165: 112020 DOI: 10.1016/j.jbiomech.2024.112020

Cite This Page:

University of Tsukuba. "Dolphin-kick swimming maximizes water-flow utilization with increasing speed." ScienceDaily. ScienceDaily, 14 March 2024. <www.sciencedaily.com/releases/2024/03/240314122152.htm>.
University of Tsukuba. (2024, March 14). Dolphin-kick swimming maximizes water-flow utilization with increasing speed. ScienceDaily. Retrieved April 13, 2024 from www.sciencedaily.com/releases/2024/03/240314122152.htm
University of Tsukuba. "Dolphin-kick swimming maximizes water-flow utilization with increasing speed." ScienceDaily. www.sciencedaily.com/releases/2024/03/240314122152.htm (accessed April 13, 2024).

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