Development and application of the sports-fluid simulator system

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In this study, we developed the sports-fluid simulator system on a personal super computer system using both of the wind tunnel experiment approach and the computer fluid dynamics approach. As typical examples of application for the sports-fluid simulator system, we analyzed sports technique from the points of view of fluid mechanics and fluid engineering and we tried to research and develop the sports equipments as sports balls and sports shoes. In the case of the fluid mechanical analysis of soccer ball, An incompressible unsteady analysis was performed using the finite volume method based on fully unstructured meshes with a commercial CFD code (FLUENT6.2, Fluent Inc.). The turbulent model of this study was Large Eddy Simulation (LES) model. The drag coefficient of non-spinning soccer ball in CFD was approximately 0.19 and that of wind tunnel test was about 0.15. It was observed that the large scale fluctuation was generated in the lift coefficient. In order to visualize the flow around the soccer ball during flight, a ball was coated as uniformly as possible with titanium tetrachloride. It seemed that the Strouhal number of wake near the real fright soccer ball was about 1.0 as similar as the high-mode value of a smooth sphere. After balls undergoing a knuckle effect were airborne, large scale fluctuations of the vortex trail were observed when the St was between 0.1 and 0.01.