This study presents a method to visualise and to analyse the wake of a swimmer's dolphin kick in a sagittal plane viewed from the side of a swimming flume using two-component PIV (2C-PIV). One trained male swimmer was instructed to maintain a swimming position with dolphin kicking. Results showed a pair of vortices and jet flow between them. The value of the jet flow velocity showed good agreement with the value of the induced velocity that was predicted by assuming that the pair of vortices represented sections of a vortex ring. It was plausible that the dolphin kicking motion performed in this study generated a propulsive force by generating the vortex ring. The vortex pair confirmed in the present study is likely of a part of this larger structure.
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