Dynamics analysis of human swimming movement using PIV and development of swimming simulation model

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Particle Image Velocimetry (PIV) enables us to visualise and analyse the unsteady flow fields. This method has usually been used for small measurement area like an analysing the airflow, mechanism of swimming/flying creatures.The purpose of this study was to clarify the mechanism of human propulsive mechanism during swimming by analysing the unsteady characteristics of flow field around swimming human using PIV method and by developing the swimming human simulation model, This is the first attempt using PIV to analyse a larger measurement area such as the flow field around a swimming human all over the world.The result of PIV study suggested that the swimming human applies the vortices (momentum) for effective propulsion. The complicated movement of hands and feet are dealt with the shed vortices and the circulation around the thrust generating body region. It was clarified that the jet flow is generated between the shed vortex and bound vortex around the hand. This change in momentum explains the propulsive force generated by the hand.Result of the study of swimming human simulation model showed that the dynamics of the underwater dolphin kick were recreated on the computer simulation. Through identification of three fluid coefficients (added mass, Fa; resistive force for normal direction, Frr, resistive force for tangential direction, Ft). Furthermore, the generated propulsive force and joint torque was calculated during underwater dolphin kicking motion. It was clarified that the propulsive force during underwater dolphin kicking was mainly generated by feet. In addition, the relationship between the flexibility of ankle and swimming performance was verified.