The effect of seam on sphere surface to the aerodynamic characteristics

Abstract

Many studies have examined the aerodynamics of soccer balls, focusing on groove depth, length, and so on. This study aimed to clarify the influence of aerodynamic characteristics for various groove volumes of various balls by conducting a wind tunnel experiments. Firstly, the drag coefficient of balls supported by piano wire is higher than that of balls supported by wire support in the supercritical region for smooth balls. However, there is no difference in drag coefficient for balls supported by wire support and piano wire in all regions for balls having panels or grooves. Secondly, in a case of without rotation, the critical Reynolds number becomes smaller as the ratio of the groove volume and the volume to ball volume increase, regardless of the size of the ball. Moreover, regarding official balls, the separation point in critical Reynolds number is constant regardless of the ratio of the groove volume and the ball volume increase. This tendency is as same as that of in supercritical region.