Fluid dynamics of cricket ball swing. (September 2013)

• Record Type: Journal Article
• Authors: Scobie, James A; Pickering, Simon G; Almond, Darryl P; Lock, Gary D
• Is Part Of: Proceedings of the Institution of Mechanical Engineers. Volume 227:Number 3(2013)
• Page Start: 196
• Page End: 208
• Publication Date: 2013-09
• Subjects: Cricket ball -- reverse swing -- boundary layer -- flow visualisation -- fluid dynamics; Sports sciences -- Periodicals; Sporting goods -- Design and construction -- Periodicals; Sports -- Technological innovations -- Periodicals; Biomechanics -- Periodicals; 613.71
• DOI: 10.1177/1754337112462320
• Languages: English
• ISSNs: 1754-3371

Abstract

Swing describes the lateral deviation of a cricket ball in its trajectory towards the batsman. Conventional swing is effective with a new, or well-preserved, ball, and the fluid dynamics governing this phenomenon was first explained in 1957. In 2012, many test-match fast bowlers are able to swing, at high speed, an older ball in the reverse direction. This reverse swing of a ball aged under match conditions has never been explained fully. A cricket ball is asymmetric with six seams of 80–90 encircling stitches, protruding approximately 1 mm proud of the surface. Both conventional and reverse swings are a consequence of asymmetrical flow separation leading to a skewed wake and a net pressure force on the ball perpendicular to the flight trajectory. Here, experimental evidence is presented for the first time showing that the formation of a laminar separation bubble is the prominent flow feature creating the flow asymmetry for reverse swing. A new flow visualisation technique to capture the fluid dynamics of boundary-layer separation using an infrared camera is also introduced here.