CFD research is invaluable for players seeking to optimize their kicking strategies
Some of the world’s greatest goalkeepers have been beaten by unusual swerving balls, which move to the left and the right before hitting the back of the net, even though they have little or no spin applied to them. New research has found that the shape and surface of the ball, as well as its initial orientation, is critical in terms of its trajectory through the air.
A team of researchers, led by Dr. Matt Carré at the Department of Mechanical Engineering at the University of Sheffield, used the most advanced software, known as Computational Fluid Dynamics (CFD), for simulating the physics of airflows in and around objects. They studied and compared airflows around four balls, all with different panel designs, each having been used at different periods over the past 36 years, including the new Adidas ball used in the 2006 World Cup.
University PhD student and Sheffield FC player Sarah Barber, alongside Dave Mann, principal engineer at Fluent, used a 3D laser scanner, similar to those used in Formula 1 motor racing, to obtain accurate surface detail of each individual ball, including their stitches and seam patterns. They demonstrated that the shape, surface, and asymmetry of the ball, as well as its initial orientation, have a profound effect on how the ball moves through the air after it is kicked. The side force varies according to the orientation of the ball relative to its flight, meaning that for a kick where the ball is slowly rotating, the side force could fluctuate causing it to swerve. Ultimately the nature of the swerve is affected by the initial orientation of the ball before it is kicked.
In collaboration with Dr. Takeshi Asai at the University of Tsukuba in Japan, the team used wind tunnel measurements to verify their CFD studies and demonstrated that in match conditions the drag of non-spinning soccer balls has fallen by as much as 30% over the last 36 years. Newer balls, like the one to be used in the World Cup last summer, which manufacturers claim to be rounder and which have more uniform seam geometry, have been found to be more consistent in high-speed kicks with little or no spin.
“Our work clearly points to the fact that any non-uniformity of design of soccer balls, or asymmetry of manufacture, will have a dramatic effect on the side forces of the ball when there’s little or no spin applied to it, and hence its swerve through the air,” says Dr. Carré. “We believe that our findings go a long way to explain the phenomenon observed when some players kick the ball with little or no spin, yet get it to swerve in a seemingly erratic manner – possibly producing an S-shaped trajectory.”
Sarah Barber added that, as a soccer player, she feels this research is invaluable in order for players to be able to optimize their kicking strategies. “This knowledge could also be used by manufacturers to design future balls, which will ultimately enhance the. . .to read the rest of the story, click here.
Websites to visit:
Ansys home
Fluent home
Sheffield FC
Official soccer World Cup website