Research Abstract


The strange flight behaviour of slowly spinning soccer balls

2013年5月22日 Scientific Reports 3 : 1871 doi: 10.1038/srep01871


溝田 武人1, 黒木 康平1*, 大屋 裕二2, 岡島 厚3, 鳴尾 丈司4 & 河村 良行1

  1. 福岡工業大学
  2. 九州大学応用力学研究所
  3. 金沢大学
  4. ミズノ株式会社


The strange three-dimensional flight behaviour of slowly spinning soccer balls is one of the most interesting and unknown phenomenon associated with the trajectories of sports balls. Many spectators have experienced numerous exciting and emotional instances while observing the curious flight behaviour of these balls. We examine the aerodynamic mechanisms of erratic ball behaviours through real flight observations, unsteady force measurements and flow pattern visualisations. The strange behaviour is elucidated by the relationship between the unsteady forces on the ball and the wake flow. The irregular changes in position for twin longitudinal vortices have already been discovered in the supercritical Reynolds number region of a sphere with a smooth surface. This finding is applicable to the strange behaviour of the flight of soccer balls with this supercritical flow. The players, spectators, and television viewers will gain greater insight into the effects of soccer ball flights.