2403 高レイノルズ数で飛翔するサッカーボール後流の動態(S43-1 スポーツ流体工学(1),S43 スポーツ流体工学)  [in Japanese] 2403 Vortex visualization on real flight soccer ball in high Reynolds number  [in Japanese]

The purpose of this study is to visualize and analyze the vortex structure around the real flight soccer ball in high Reynolds number. In order to visualize the flow around the soccer ball during flight, a ball was coated as uniformly as possible with titanium tetrachloride. A subject then kicked the ball, and this activity was filmed at 4,500 fps with a high-speed video-tape recorder camera (Photron Ultima ; Photron Inc.). At an outside air speed of≤1.0m/s, the subject performed an almost non-spinning straight kick and a laterally spinning curved kick towards the middle of a goal from a distance of 15m. Images were recorded in black and white (256×256 pixels) and then uploaded onto a computer as AVI files. 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. It was observed that the vortex pairing in the wake.