An experimental study using particle imaging velocimetry on the frequency of fishtails generating underwater thrust

Many creatures swim underwater in nature, such as fish, dolphins, and penguins. The most important aspect of swimming is generating propulsion with the tail, which allows the organism to perform a variety of movements. This study aims to understand and simulate the mechanism of underwater swimming by analyzing the hydrodynamics generated by tail movement. As an experimental technique, particle image velocimetry was used to analyze the flow environment generated in a circulating water tunnel and physical quantities were obtained through various measurement systems. We found that when the frequency of the tail is above 1Hz, there is a singularity between velocity and frequency. Based on this, we plan to use it to utilize the mechanism of underwater swimming and to realize a robot that can simulate it.