World Cup and football in aerodynamics _ science squirrels will

South Africa World Cup, scoring a direct free kick keeper "rare, butter hand" events and long transmission errors is increasing, this is all so bad aerodynamics. Ghosts for doors (this article in the World Cup at the opening of the night, the main c Luo. But this guy is so poorly, abolishing early. To commemorate my 2010 South Africa World Cup. ) When taking home advantage in Ghana with a 35 meter long shots of rebound the ball knocked on the door to Uruguay, the African team looks to be a historic first broke into the top 4. Until the second half 55 minutes, Ghana's restricted area outside two metres on the right corner, and Uruguay for a valuable free kick opportunities. Typically, a closed arc top is the best regional direct free kick, and the angle so partial location free player tends to be the ball to a 6-yard line near to expect big teammate Didier attack. Uruguay leader Evelyn laid the ball, a 4-step approach, with the ball in the instep of the lower side, "celebrated" quickly fly up high over three defensive players of a human head. Flash, Ghana goalkeeper was aware, the ball does not pass, which is a South American technical players frequently used "banana ball", the door he guarded, so the visitor into the corner to move the body right a small step. However, when "celebrated" cross the barrier, the unexpected happened: suddenly went far angle of turning and high-speed descent. Loss of position in Emily Dickinson's only flying jumps, trying to stretch your arms to save the ball, but failed to reach the ball's edge — the ball into the crazy Uruguay players celebrate!, Dickinson's puzzle is a face. After the match, Clermont won the FIFA player of the fish farm, his direct free kick help Uruguay 60 years again killed in 4. On this free kick broke, the media called the strange, that it is simply a "free kick" S-shape. S-free kick and resistance mutations in fact in physics, study of the "banana ball" is not a new stuff. The earliest of its mechanical principle is our ubiquitous seamless not in Newton, ladies. In 1667, at the age of 23 he had already given the tennis ball rotation and arc interrelationship between insights. So far it appears that his explanation or rather rely on the spectrum: when a sphere in rotation, one side than the other side more intense, thus able to squeeze the gas causes greater impediment. Now we know this phenomenon is Magnus effect. It is in 1877, Rayleigh, Lord (LordRayleigh) thesis, to first correct interpretation of the phenomenon of Germany physicist Hein Ridge • Magnus (HeinrichMagnus) name officially named. Magnus found a rotation along the symmetry of a cylinder in vertical symmetry axis to stream from a lateral forces. Newton and Magnus in fact, just give us a story's a start, and the Poulenc (LudwigPrandtl) then brought the fluid dynamics of a complete revolution. In 1904, he found that all the objects in a fluid, whether it be aircraft, artillery, or fish, tadpoles are wrapped layers invisible fluid clothes--"boundary". In order to clarify this concept, let's discuss a simpler problem: air lines does not spin of the ball. When a ball in the air gliding, contact with the sphere of air forever and spherical to the contact points have the same size and orientation. Therefore, immediately sphere of a layer of air is like a jacket,-equating to follow the ball movement. Ball at rest, and he slept; globe direct flight, he also followed the move if tuotu. In this layer in the layer on the outside of the bag will be slightly relaxed a little, like a light shirt. It can be as tight campaign, but not as tight on sphere then boys. Then the outside layer is the more relaxed leisure plush jacket. Such a layer with a layer of clothing until the outermost layer is more relaxed and elegant Orchid feather clothing of NI, basically not rotate with the ball. Scientists by measuring air speed, if a layer of air speed only spherical contact point speed of 5% (or someone using 1%), they define this layer "clothes" is "mashup" outer border look. "Coat" into the part between the spheres together is called a "boundary layer (boundarylayer; aviation science, also known as the boundary layer)". The boundary layer is very thin, for example, a one-metre-long flat to 20 meters per second speed flying parallel to the stream, boundary layer thick place probably only 3 mm. Prang-(LudwigPrandtl) greatly (http://www.aps.org/units/dfd/resources/images/prandtlarfm.jpg) through the boundary layer, sphere sport and a close relationship with the outside world. Because the boundary layer of clothes, the cross is not tight. Each layer can occur between the relative motion and relative friction. The friction will turn the sphere of energy consumed, thereby slowing down the motion of the ball. This is a fluid friction. However, the friction resistance tend to be remembered. At the high-speed flow, sphere will continually show "striptease" (boundary layer separation, boundarylayerseparation). Fun is that those who love the clothes are behind the ball. These sexy naked outside will form a low-speed zone. There are not only destroying clothes flying, floating, pressure is relatively low. As a result, the ball in front of the air on the back of the young man has advantages, spell a life back. This can greatly increase the sphere feel resistance, thus forming a "shape resistance". Frictional resistance and shape resistance work together to make up the fluid resistance. In order to allow specific experimental results with universality, the scientists used a resistance factor to represent the size of the resistance. For the same object the same upwind flight speed and direction, the greater the resistance coefficient means that the greater the resistance. Wind tunnel experiments on the smoke flow line (left flow boundary layer attached to football, smoke line parallel to each other; on the right side of the white area boundary layer separation, flow disturbance, disruption of smoke line) when the ball spin, it is much more lively and sexy. If you stand on the ball, you will findRotate the ball always has a down side towards the wind ahead of the other side is along the slope to ride a donkey fengshun (fig). "Brave" side of "dress" is "restricted" brave. Boundary layer of the air along the surface of the sphere, the backward movement early on was off the back. "Sloping donkey" in the air in the boundary layer in a lazy ass "under", can drag it onto your late than many of those off. As a result, the "brave" is closer to the truth (who let the naked truth?), sloping down ass tight to the wrapped more. And drag the "type" produced by the same token, the naked side have a higher-speed zone. Sphere is very shy and always want to get naked side guards behind, so I slowly toward the downslope under donkey that fly away. So, you finally found the "banana ball" formed a! and with the speed increased, this trend even more strongly. (Physics terminology explained: boundary layer separation is always on the upwind side of advance, before the wind face delays. This asymmetry makes gravity and drag outside of lateral force. ) Today, Magnus effect has been reduced to such a boundary layer separation of asymmetry. Thus, we suddenly understand the overland's two free kick features: banana ball from football fast rotation, and the fast rotating balls from his moment of wiping the ball when. With shoelaces part touch increased ball speed forward roll. This erratic s-what's up? resistance curve, with the speed (abscissa of the Reynolds number), we find the drag coefficient (ordinate) have a dump. This is not a test inaccurate. But science infamous insurmountable "turbulence" role of! the drag coefficient dump occurred the Reynolds number is called the critical Reynolds number. If a non-rotating sphere, speed reaches a certain level, sphere Reynolds number will exceed the critical Reynolds number (probably thousands to half a million or so). Boundary layer of the air will suddenly become "turbulence", boundary layer into a turbulent boundary layer. Turbulent boundary layers with more energy, can ball wall attachment. Sphere if you spin it, go back to go forward and go forward sloping down ass: too brave (speed high enough), moving forward would be the first to make up the abruptly put on the results of the brave, than with cloth slope was also under donkey wrapped tight, thereby weakening the naked part corresponds to the low speed zone. In order to take part in the naked behind, sphere will be to DDP slope side movement under donkey (anti-Magnus effect). As the speed decreased, sphere sport of Reynolds number and lower than the critical Reynolds number, turbulence will disappear. According to the generality of the foregoing, inference, sphere and instantly to your side. Turning moment, speed relative increase turbulence may appear again. Therefore the Reynolds number may be repeated from near the critical value, and the drag coefficient will return of mutations, the goalkeeper will find ball movement direction erratic — Ivelin's free kick is probably exactly what is approaching critical ball speed range, therefore appeared strange S-shape. Resistance curve (abscissa Reynolds number, ordinate drag coefficient) (from: Mehta, R. D., 1985) stop rotation of slow change ball from England's Green, goalkeeper constantly put on a "butter hand", even the best goalkeeper in the world, one of Spain's Casillas also appear more than once at the ball out of bounds, Brazil's Cesar is because there is no judgment on the Netherlands people, Ned free kick ball road, cause an unexpected out of Brazil. Not only goalkeeper, players also blame the World Cup ball "celebrated" doesn't work, particularly noticeable is the high card player's long pass failures increases. But the manufacturer adidas corporate response, compared to past 14 block skin, the new football by 8 block skin and surface and air Dynamics Groove, and passed the strict wind tunnel tests. Overall stability improved by 30%. "Celebrated" is the 2006 World Cup with the star of the "team" upgrade Edition. At that time, adidas says it is the world's most accurate football players complain about it, but they used to play football. Now the "celebrated" encounter with the star of the "team" and the same problem. One of the main problems is the so-called "slow change ball" (Knuckle-balling). This variable line ball in ball's movement, the ball's trajectory will occur to unknown direction. This phenomenon is attributed to a ball in straight flight, the ball does not produce rotation. (That's a bit like bullets, if the bullet from gun out, without a Clave line to rotate, the bullet will be launched to target direction on Flip, bullet not far, it has lost it's destruction. Bullet this spin, is the use of the physics in the tenets of the "gyro rotation". ), Ironically, this kind of out of rotation of the ball, due to the influence of aerodynamic aspects, will make the ball from the normal path of deviation. This spherical ball is not complete and smooth surface and epidermal adhesion between the Department, there is a seam, sphere surface not smooth, it is precisely because of these joints in convex boundary exists. Sphere surface irregularities which sphere in runs, it produces around asymmetrical flow, causing the ball to the direction of the air pressure is small. Ball of the General design and the new Groove makes it equivalent to a restricted area around the free kick was kicked out of speed, in a normal ball speed, "celebrated" easier to become slow change ball. Portugal c-it is good at making this little spinning free kick expert, but this Cup, really shoot out letdown of slow change ball, only Japan player Honda Kyu Woo. In the match against Denmark, he distance goal 37 m position, injection speed of 107 km free kick, then celebrated it howled to goal corners, allowing Denmark goalkeeper and goalkeeper Sørensen. 【 Edit: Nanto weekly song Shuang 】 reference literature: Mehta, R. D. (1985). Aerodynamics of Sports Balls. AnnualReview of Fluid Mechanics, 17(1), 151-189. doi:10.1146/annurev.fl.17.010185.001055.Mehta, R. (2009). Sports Ball Aerodynamics. SportAerodynamics, 229–331. Springer. Retrieved from http://www.springerlink.com/index/p47jwq6854714567.pdf. farm what football physicists? Drogba (Côte d'Ivoire), 32-year-old Drogba will be Magnus effect of the use of better and better, just ended United Kingdom FA Cup final, he relies on a rotating foot is not strong but falling very fast direct free kick break England gates of James's ten fingers off. Interestingly, he and Roy will be in Group C game. , Ned (Netherlands), Ned is Sanguan Inter Milan won the King of one of the greatest hero, his free kick from a greater distance from the power of gun and alarming. This season, the arena in inter 4-3 Siena in reversing, Ned into two direct free kick. But in the Netherlands, he can only be used with another free kick masters van Persie equally kicked a penalty goal kick. Pierluo (Italy) pierluo chic's "elevator ball" is the Magnus effect. As Italy's first free kick, he kicked the ball very few large arc, from looking at almost straight down. But his ball often drop-down drift, and allow goalkeeper, odd by surprise. In last year's Champions League group games shooting Real Madrid's long shots is a classic. Zhongcunjunfu (Japan) in the left foot of the village is Japan in midfield, his free kick both deciduous and characteristics of banana ball, the ball speed more quickly. The representative of the 2007 Celtic on Manchester United Champions League tournament, free kick break beat Manchester United 1-0. This article has been published in the Zuid are weekly, changes