抄録
Non spinning serve or shot exist as a technique in volleyball and soccer ball. Because the flight paths of these non-spinning balls are not stable. In the volleyball, it is called floater serve. Floater serves in volleyball and erratic path shots of the soccer ball are different in their speed area. In other words, they are the phenomena in a transition region on volleyballs and that in the super critical domain on soccer balls. It is thought that origin of each erratic phenomenon is different. In this study, three dimensional twin vortices were visualized behind volleyball using three-dimensional dynamic PIV and solved the origin of erratic motion on the floater serve. Quick motions of three-dimensional twin vortices were confirmed in the transition region on volleyball.
