Whether you’re a golf enthusiast or just find yourself walking by a package of golf equipment in a store, you may have wondered why the sport's round white balls have hundreds of tiny depressions on their surface. Are these dimples just for looks, or do they serve a purpose?
As it turns out, the dimples make the game of golf possible. The dimples facilitate aerodynamic optimization, or the ability of the ball to travel longer distances by influencing the lift and drag of an object in the air. (Lift goes in the direction perpendicular to motion; drag opposes motion.) According to Scientific American, a dimpled ball travels twice as far as a smooth one would. That’s because the dimples produce a boundary of air around the ball, reducing the wake of air as well as the drag. They also act as turbulators, inducing turbulence in the layer around the ball.
The design also contributes to the lift of the object, with roughly half of the lift the result of the ball’s spin and the other half a product of the optimization of the lift force from the dimples.
The overall result is that air flows more smoothly around the ball, with air in front of it moving faster. The ball is essentially in the middle of a perfect aerodynamic sandwich, with higher pressure behind it pushing the ball forward and reduced pressure in front of it allowing air to move faster.
The depth of the dimples can also make a huge difference. A typical golf ball has 300 to 500 dimples, with an average depth of 0.010 inches. Most are spherical, though some companies have adopted a hexagon shape in order to reduce drag further.
Golf balls weren’t always pockmarked. Early players used smooth balls but noticed that the more a ball got nicked and damaged, the further it would travel. In the case of a golf ball, form definitely follows function.
[h/t Scientific American]
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