Researchers are beginning to uncover how bowling nearly parallel to the ground in cricket results in extremely challenging balls for batters to hit. A team used a specialized wake survey rake device, made up of several tubes, to measure the pressure behind the ball and studied the airflow of cricket balls spinning at speeds of up to 2,500 revolutions per minute in a wind tunnel. Their findings showed that low-pressure areas grew and strengthened around the spinning ball, while these areas shifted and weakened as they moved downstream. At increased spin rates, the low-pressure area transitioned into a consistent bilobed shape. This research supports the theory that these modern bowling techniques utilize the Magnus effect.
A crucial element in winning a cricket match is outsmarting the opposing team’s batters—a challenging task considering that bowlers can deliver cricket balls at nearly 100 miles per hour. Recently, a bowling method that has gained popularity involves maintaining a nearly horizontal arm during the bowl, as famously demonstrated by Sri Lankan players Lasith Malinga and Matheesha Pathirana. The aerodynamics behind these throws have intrigued sports physicists.
In the journal Physics of Fluids published by AIP Publishing, researchers have begun to unveil how this bowling style results in difficult-to-hit balls. Faazil et al. used a wind tunnel to analyze changes in pressure around a ball caused by the spin from near-horizontal bowling.
“The unique and unconventional bowling techniques showcased by cricketers have attracted considerable attention, particularly highlighting their skill with a new ball at the start of a match,” remarked author Kizhakkelan Sudhakaran Siddharth. “These techniques often mislead batsmen, making these bowlers effective throughout all phases of a match across nearly all formats of the game.”
The degree and manner in which a cricket ball curves during its flight depend significantly on the relationship between the ball’s spin and the operational Reynolds number—a dimensionless figure that relates to fluid density, ball size, air speed, and fluid thickness.
To address their research question, the team utilized a wake survey rake device with multiple tubes to analyze pressure downstream of the ball. This was enhanced by an imaging system designed to detect pressure changes recorded in the connected manometers. The research focused on the airflow dynamics of cricket balls spinning at rates of up to 2,500 rpm in a wind tunnel.
“The combination of the simultaneous traversal-imaging technique and the traditional manometers we used in this study provided impressive accuracy, surpassing all our expectations,” Siddharth stated. “This method proved to be an excellent way to replicate the complex and dynamic conditions seen in sports within a wind tunnel setting.”
The findings revealed that low-pressure zones expanded and became more pronounced around the ball during spinning, and these zones shifted and weakened downstream. At higher spinning speeds, the low-pressure area transitioned into a stable bilobed shape.
The results support the theory suggesting that these new bowling styles leverage the Magnus effect, which describes how high-speed spinning can alter a ball’s trajectory midflight.
Siddharth hopes this research fosters greater interest in exploring the physics behind cricket ball dynamics. The team aims to further investigate how different factors, such as the ball’s wear and tear, influence aerodynamics.
