Study of the 2014 World Cup in Brazil ball "samba glory" technology secrets

Early on the 26th, Argentina and Nigeria staged a scoring war. The first half overtime period, "small fleas" Messi free kick set a high arc, the Nigerian goalkeeper can only look at the ball 蹿 goal.

Since the start of the World Cup, many players have scored wonderful goals. These goals, and some full strength, and some arc strange, some angles tricky. Players into these waves of the world, in addition to the state of the game is good, with the players with understanding, ultimately, the World Cup ball "Samba honor" credit.

The 2014 FIFA World Cup has aroused the excitement of many fans, including NASA engineers. Although NASA did not participate in the design or testing of football, scientists believe that the World Cup offers an opportunity to explain the principles of aerodynamics. By studying the World Cup, people know the technological secrets behind football.

"Potevio celebrates" too weird

In a lab at the NASA Ames Research Center in California, USA, scientists used smoke, laser and fluid to build a test room to study aerodynamically the science and technology secrets of the 2014 World Cup in Brazil, "Samba Glory." .

Rabin Mehta, chief aerodynamic instructor at Ames Research Center, said aerodynamics are the objects of air and liquid that are collectively referred to as "fluids" in aerodynamic research. Rabbi Meta and engineers put "Samba Glory", traditional football and the 2010 South Africa World Cup ball "Celebrations" and other test balls were placed in the test channel.

In this 43-centimeter-long waterway, researchers use fluorescently-stained liquids to observe fluid morphology around the sphere. They found that World Cup players usually play at speeds of 80 to 89 kilometers per hour. The smoother "All Day Celebration" produces the largest elevator ball effect at about 80 km / h, explaining that players often kick the elevator ball at the 2010 World Cup.

"Celebrate all over the world," although easy to produce elevator balls, but this ball shape is too rounded, the flight path more elegant. US media reported that at the 2010 World Cup in South Africa, "all-around celebration" showed some "supernatural" state of mind, not only let the goalkeeper know what to do, forward midfielder also repeatedly complained that the ball can not control.

Elevator ball more difficult to kick

It is not uncommon to take full advantage of the ball's flying characteristics to gain athletic advantage. Take a baseball game as an example. The pitcher controls the rotation of the ball according to the suture of the ball and throws balls of different trajectories such as an arc ball, a fast ball, a sliding ball and a finger ball. For football, although the surface of the ball is not prominent suture, but most of the soccer ball is seamed.

Samba Glory has fewer faces than previous World Cup balls, but the seam length between these finger-like faces has increased. The depth of these seams has deepened compared to "all-day celebrations." The sphere is also covered with bulges, all of which affect the ball's aerodynamics.

In the usual impression, the gas is moving around the sphere. In fact, this statement is not accurate, the airflow around the sphere is not smooth, resulting in a considerable pull behind the ball. For example, on a golf course, smoother golf balls are shorter than normal, uneven golf balls. The dimples on the surface of the sphere can agitate the air and produce a small low-pressure wake behind the sphere, thus reducing the pulling force and lengthening the ball's movement distance.

"A very thin layer of air near the surface of the sphere, called the boundary layer, is the state of the boundary layer and the changes that affect the movement of the ball," said Rabbi Mehta. "The materials used for football are spherical Roughness affects its aerodynamic properties. "

The smoother the sphere, the higher the speed required to kick the ball out of the elevator. As the "Samba Glory" increases the roughness of the spherical surface, the maximum elevator ball effect critical speed has dropped to 48 km / h. Therefore, the increase of overall roughness of "Samba Glory" will reduce the probability of elevator ball in terms of the usual playing speed at the World Cup.

"Samba glory" more stable

2006 World Cup in Germany, "Team Star", 2010 World Cup in South Africa, "all-rounders" are not to be seen by goalkeeper. They complain about the trajectory of the ball is too weird. The current World Cup, "Samba glory" performance fairly normal.

It is reported that the "samba glory" of the sphere of the surface composed of five materials to ensure that after the kick in the football can resume its original shape, which makes the spherical particularly durable and flexible. The innermost layer of the bark is a bond coat, here a polyurethane foam, consisting of microspheres filled with millions of gases. The outer skin of the football consists of three layers of compact layers of different thicknesses. These compact layers provide excellent resistance to external influences and wear, as well as high elasticity of the soccer ball. In addition, its spherical surface also has 50,000 small bumps, which can increase the contact surface of the ball and the foot, increase the rotation of the sphere when the ball touch.

Rabbi Mehta of NASA's Ames Research Center said Samba Glory moves faster and has a better stability than "Celebrate It All." "The players should be more satisfied with this new game ball, which is more stable to fly and kicks it more like traditional football spliced ​​together in 32 planes."

Last year's test, Spain's captain Casillas, the captain of Spain's test team, said: "The design of the 'Samba glory' is enviable and has a strong Brazilian style. It is very similar to the ball used in the Champions League, so I believe The players will be very happy about this and I look forward to dancing with this wonderful football in Brazil. "Perhaps it is because of the" samba glory "light weight fast ball, the trajectory of the ball stable before stimulating the World Cup can produce More goals. Casillas suffered two humiliating competitions, ahead of the World Cup stadium.

Edition author / Beijing News reporter Han Xuyang intern Wang Xiu