The World Cup ball has the aerodynamics of a champion


An Adidas Al Rihla ball during the international friendly match between Japan and the United States at Merkur Spiel-Arena on September 23, 2022 in Dusseldorf, Germany.
Zoom in / An Adidas Al Rihla ball during the international friendly match between Japan and the United States at Merkur Spiel-Arena on September 23, 2022 in Dusseldorf, Germany.

As with every World Cup, at World Cup 2022 In Qatar, players will use a new ball. The last thing competitors want is for the most important piece of equipment at the most important tournament in the world’s most popular sport to behave in unexpected ways, so a lot of work goes into making sure every new World Cup ball looks familiar to players.

I am a physics professor In the Lynchburg University Who studies sports physics. Despite the controversy over corruption and human rights issues surrounding this year’s World Cup, there is still beauty in the science and skill of football. As part of my research, every four years I analyze a new World Cup ball to see what went into creating the centerpiece of the world’s most beautiful game.

Cloud physics

Between shots on goal, free kicks and long passes, many of the key moments in a soccer match happen when the ball is in the air. So one of the most important characteristics of football is how it travels through the air.

At lower speeds, the air will hug the surface of just the front half of the football before being extruded in an orderly fashion called laminar flow, as shown here in this wind tunnel image.
Zoom in / At lower speeds, the air will hug the surface of just the front half of the football before being extruded in an orderly fashion called laminar flow, as shown here in this wind tunnel image.
At high speeds, the air flowing over the soccer ball travels almost entirely to the back of the ball before breaking up in chaotic eddies called turbulence.
Zoom in / At high speeds, the air flowing over the soccer ball travels almost entirely to the back of the ball before breaking up in chaotic eddies called turbulence.

As the ball moves through the air, a thin layer of mostly still air called the boundary layer surrounds part of the ball. At lower speeds, this boundary layer will only cover the front half of the sphere before the flowing air peels away from the surface. In this case, the wake up of air behind the sphere is more or less uniform and is called laminar flow.

When the ball is moving fast, the boundary layer wraps more around the ball. When the airflow eventually breaks away from the surface of the sphere, it does so in a series of chaotic eddies. This process is called turbulent flow.

When calculating the amount of force that moving air imparts to a moving object — called drag — physicists use a term called the drag coefficient. For a given speed, the higher the drag coefficient, the more drag the body feels.

It turns out that the soccer ball’s drag coefficient is About 2.5 times greater for laminar flow than for turbulent flow. Although it may seem counterintuitive, roughening the surface of the sphere delays the separation of the boundary layer and keeps the sphere in the turbulent flow longer. This physical fact—that rough balls feel less drag—is why dented golf balls fly farther than if the balls were smooth.

When it comes to making a good soccer ball, the speed at which the airflow goes from turbulent to laminar is crucial. This is because when this transition occurs, the ball starts to slow down significantly. If the laminar flow starts at a very high speed, the ball starts to slow down much faster than a ball that maintains the turbulent flow for a longer time.

The evolution of the World Cup ball

Adidas Telstar, which appeared in the 1970 and 1974 World Cups, is what many people imagine when they think of soccer.
Zoom in / Adidas Telstar, which appeared in the 1970 and 1974 World Cups, is what many people imagine when they think of soccer.

Adidas has supplied balls for the World Cup since 1970. And throughout 2002, each ball was made from the iconic 32 panels. The 20 hexagonal and 12 pentagonal panels were traditionally made of leather and sewn together.

A new era began with the 2006 World Cup in Germany. The 2006 ball, called Teamgesit, is made up of 14 smooth synthetic panels thermally bonded together instead of stitched. The tighter adhesive seal keeps the water outside the ball inside on rainy and wet days.

Making a ball out of new materials, with new technologies and fewer boards, changes how the ball moves through the air. Over the past three World Cups, Adidas has tried to balance the plate number, seam properties and surface texture to create balls with just the right aerodynamics.

The Jabulani eight-panel ball at the 2010 World Cup South Africa had textured panels to compensate for the shorter seams and fewer panels. Despite Adidas’ efforts, Jabulani was a controversial ball, with many players complaining that it suddenly slowed down. When my colleagues and I analyzed the sphere in a wind tunnel, we found that Jabulani was very smooth overall It thus had a higher coefficient of drag than the 2006 Teamgesit ball.

Jabulani's smoother ball from the 2010 South African World Cup has received a lot of criticism for being slow in the air.
Zoom in / Jabulani’s smoother ball from the 2010 South African World Cup has received a lot of criticism for being slow in the air.

The World Cup balls for Brazil in 2014 – the Brazuca – and Russia in 2018 – the Telstar 18 – had six oddly shaped panels. Although they have slightly different surface textures, they generally have the same overall surface roughness, and thus, Similar aerodynamic characteristics. players in general I love brazuca and Telstar 18, but some complained of a mile Telstar 18 to pop easily.



Source link

Related Posts

Precaliga