Why are there dimples on the surface of golf balls and how do they function?

Question

Why the golf balls being used have "dimples" on the surface?

Answer 1

Originally, golf balls were smooth; but golfers noticed that older balls that were beat up with nicks, bumps and slices in the cover seemed to fly farther. Golfers, being golfers, naturally gravitate toward anything that gives them an advantage on the golf course, so old, beat-up balls became standard issue.

At some point, an aerodynamicist must have looked at this problem and realized that the nicks and cuts were acting as "turbulators" -- they induce turbulence in the layer of air next to the ball (the "boundary layer"). In some situations, a turbulent boundary layer reduces drag.

Answer 2

The dimples are usually the same size as one another, but some golf balls have several different sizes of dimple on the same ball. Any number between 300 and 500 dimples is reasonable, and 336 is a common number.

Dimples on a golf ball create a thin turbulent boundary layer of air that clings to the ball's surface. This allows the smoothly flowing air to follow the ball's surface a little farther around the back side of the ball, thereby decreasing the size of the wake.