Mehta Rabindm D., Pallis Jani Macari. Sports Ball Aerodynamics: Effects of Velocity, Spin and Surface Roughness

12 p.Aerodynamic principles affect the flight of a sports ball as it travels through the air. From the design of dimples on a golf ball or the curved flight path of a tennis, cricket or baseball, aerodynamics affects speed, motion (position and placement) and ultimately athletic performance.
The aerodynamics of several different sports balls, including baseballs, golf balls, tennis balls, cricket balls, volleyballs and soccer balls are discussed with the help of recent wind tunnel measurements and theoretical analyses. An overview of basic sports ball aerodynamics as well as some new flow visualization data and aerodynamic force measurements are presented and discussed. The materials include explanations of basic fluid dynamics principles, such as Bernoulli's theorem, circulation, the four flow regimes a sphere or a sports ball encounters, and laminar and turbulent boundary layers. The effects of these specific mechanisms on the behavior and performance of sports balls are demonstrated. The specific aerodynamics of the strategic pitches, serves, kicks and strokes used in each sport are described. In particular, the effects of surface roughness and spin on the behavior of the boundary layers and the critical Reynolds number are discussed here.