Search results for: “aerodynamics”

Formula 1 Aerodynamics
[original media no longer available]
Computational fluid dynamics (CFD) and the advent of supercomputing have forever changed the way engineers design. Here the use of CFD in the design of Formula 1 racing cars is discussed. Although CFD is used by many companies in place of wind tunnel testing, each method has its advantages. CFD provides information about all flow quantities at all points in the flow but can only do so with an accuracy dependent on the grid and models used. It remains impossible to solve the equations of motion exactly for any problem of practical application because the computational cost is simply too high; instead software packages like FLUENT utilize turbulence models that approximate the physics. Wind tunnel testing, on the other hand, is physically accurate but typically yields only limited data and flow quantities due to the difficulty of instrumentation. (Video credit: BBC News; submitted by carhogg)
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September 20, 2012
London 2012: Soccer Aerodynamics
Corner kicks and free kicks are tough to defend in football (soccer for Americans) because the ball’s trajectory can curve in a non-intuitive fashion. Known as the Magnus effect, the fluid dynamics around a spinning ball cause this curvature in the flight path. When an object spins while moving through the fluid, it drags the air near the surface with it. On one side of the spinning ball, the motion opposes the direction of freestream airflow, causing a lower relative velocity, and on the opposite side, the spin adds to the airflow, creating a higher velocity. According to Bernoulli’s principle, this causes a lower pressure on the side of the ball spinning with the flow and a higher pressure on other side. This difference in pressure results in a force acting perpendicular to the direction of travel, causing the unexpected curvature in the football’s path. In the case of the corner kick above, the player kicks the ball from the right side, imparting an anti-clockwise spin when viewed from above. As the ball travels past the goal, air is moving faster over the side nearest the goal and slower on the opposite side. The difference in velocities, and thus pressures, creates the sideways force that drives the ball into the goal even without touching another player. The same effect is used in many other sports to complicate play and confuse opponents. In tennis and volleyball, for example, topspin is used to make the ball drop quickly after passing the net.
ETA: Check out this other great example of a free kick sent in by reader amphinomos.
FYFD is celebrating the Olympics by featuring the fluid dynamics of sport. Check out some of our previous posts including the flight of a javelin, how divers reduce splash, and what makes a racing hull fast.
August 9, 2012
London 2012: Running Aerodynamics
Running is not an event typically associated with aerodynamics, though any runner will tell you that a headwind can slow them down. For comparison, a swimmer on world record pace sees 40 to 50 times the drag force of a runner over the same distance. But despite the relatively small influence of drag on a runner, there are measurable effects due to wind and altitude when races are judged by hundredths of a second. Given this, it comes as no surprise that researchers (and presumably manufacturers) are starting to considering how to optimize aerodynamics in running. The video above describes results of a study on running shoes that suggests modest savings may be derived from shoes with dimpled surfaces, much like a golf ball. Socks, on the other hand, don’t show any aerodynamic savings from special surfaces. Of course, the bulk of a runner’s drag comes from their hair and clothing; this is, in part, why runners wear form fitting clothes. While there may be some aerodynamic savings to be had, I don’t think we’ll see world records falling like crazy in Rio because of the latest new shoes.
FYFD is celebrating the Olympics by featuring the fluid dynamics of sport. Check out our previous posts on how the Olympic torch works, what makes a pool fast, the aerodynamics of archery, the science of badminton, how cyclists get “aero”, and how divers reduce splash.
August 6, 2012
Jump Rope Aerodynamics
Researchers have used high-speed video and numerical simulation to capture the effects of aerodynamics on jump roping. After videoing an athlete jumping rope and constructing a jump roping robot (shown above imaged multiple times with a strobe light), they found that the U-shaped tip of the jump rope bends away from the direction of motion. When they built a computer model capable of deforming the jump rope based on its drag, they found the same behavior. They concluded that the “best” jump ropes are lightweight, short, and have small diameters to maximize speed and minimize the drag. #
November 2, 2011
Aerodynamics with Bill Nye and Samuel L. Jackson
Bill Nye, Samuel Jackson, golf balls, Reynolds number, dimples, and boundary layers. It doesn’t get much better than this. – Khristopher O (submitter)
It definitely beats Jackson’s other foray into aerodynamics! The dimples on a golf ball cause turbulent boundary layers, which actually decrease drag on the ball and make it fly farther. Why bluff bodies experience a reduction in drag as speed (and thus Reynolds number) increases was a matter of great confusion for fluid mechanicians early in the twentieth century, but it’s not too hard to see why it happens with some flow visualization.

On the top sphere, the laminar boundary layer separates from the sphere just past its shoulder. This results in a pressure loss on the backside of the sphere and, thus, an increase in drag. On the bottom sphere, a trip-wire placed just before the shoulder causes a turbulent boundary layer, which separates from the sphere farther along the backside. This late separation results in a thinner wake and a smaller pressure loss behind the sphere, thereby reducing the overall drag when compared to the laminar case. (Photo credit: An Album of Fluid Motion)
March 14, 2011
Pterosaur Aerodynamics
The pterosaur was an enormous prehistoric reptile that flew with wings of living membrane stretched over a single long bone, unlike any of today’s flying creatures. New research using carbon fiber wing analogues and wind tunnel testing suggests that the pterosaur would have been a slow, soaring flyer well adapted to using thermals for lift. Once on a thermal, the pterosaur could coast, perhaps for hours at a time, with little to no flapping necessary. See the research paper or the Scientific American article for more. #
November 25, 2010
Flying Fish Aerodynamics
New research using wind tunnel measurements of (dead) flying fish is giving new insight into how these fish are able to fly over the waves. Lift and drag data indicates that flying fish have a gliding ability comparable to soaring birds like hawks! #
September 10, 2010
Escape From Yavin 4
In an ongoing tradition, let’s take another look at some Star Wars-inspired aerodynamics. This year it’s the TIE fighter’s turn. Here, researchers simulate the spacecraft trying to escape Yavin 4’s atmosphere at Mach 1.15. The research poster’s blue contours show pressure contours, with darker colors connoting higher pressures. The bright low pressure region immediately behind the craft suggests a difficult, high-drag ascent and a turbulent, subsonic wake despite the craft’s supersonic velocity. (Image credit: A. Martinez-Sanchez et al.)
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May 5, 2025
Paris 2024: Tennis Racket Physics
Like many sports that feature balls, spin plays a big role in tennis. By imparting a topspin or backspin to a tennis ball, players can alter the ball’s trajectory after a bounce and, using the Magnus effect to alter lift around the ball, change how it travels through the air. For example, a ball hit with backspin can dive just after the net, forcing an opponent to scramble after it. How much spin a player can impart depends on the speed of the racket’s head. Competitive rackets are carefully engineered — in terms of weight, string tension, and frame stiffness — to translate the kinetic energy of a player’s swing into the ball. But aerodynamics also play a role: new rackets designed to minimize drag hit the market 15-20 years ago, promising drag reductions up to 24% compared to previous rackets. That gives a player more swing speed and higher spins at a lower energy cost. (Image credit: C. Costello)
Related topics: The Magnus effect in table tennis and in golf; the reverse Magnus effect
Check out more of our ongoing and past Olympic coverage here.
August 6, 2024
Paris 2024: Beach Versus Indoor Volleyballs
Some of the differences between beach volleyball and indoor volleyball are obvious, like the number of players allowed — two versus six — and the courts — a smaller sand court versus a bigger indoor court. But there are subtle and significant differences in the balls themselves. Both beach and indoor volleyballs used for competition are required to weigh between 260 and 280 grams, but the expected diameter of the balls differs by about 1 centimeter, with beach volleyballs coming out slightly larger. The balls differ in their surface roughness, too, with indoor models being smoother, even before in-game wear.
Although these differences seem minor, they can make a significant impact in the game. Volleyball regulations don’t specify a ball’s expected surface roughness or how many panels they should be made with. As in football, these seemingly cosmetic changes can strongly affect airflow around the ball and change its trajectory. Regulations require that all balls used in a given match be uniform, but that still requires athletes to potentially adjust to the behavior of a new ball at each competition. (Image credits: I. Garifullin, C. Chaurasia, C. Oskay, and M. Teirlinck)
Related topics: How smoothness and panel design affect a football, volleyball aerodynamics, and vortex generators on cycling skinsuits
For more ongoing and past Olympic coverage, click here.
August 5, 2024

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