Why dimples on a golf ball

Sign up for our Newsletter! Mobile Newsletter banner close. Mobile Newsletter chat close. Mobile Newsletter chat dots. Mobile Newsletter chat avatar. Mobile Newsletter chat subscribe. Golf Basics. Those dimples actually serve an aerodynamic purpose. How Golf Clubs Work What is the history of golf? Top 10 Golf Swing Tips. The bottom portion moves fast relative to the air around it; there is more drag on the air passing by the bottom, and the boundary turbulent layer is relatively thick; air in the not-too-near region moves more slowly relative to the ball.

The Bernoulli force produces lift. Alternatively, one could say that "the flow lines past the ball are displaced down, so the ball is pushed up. A difficulty comes near the transition region between laminar flow and turbulent flow. At low speeds, the flow around the ball is laminar. As speed is increased, the bottom part tends to go turbulent first.

But turbulent flow can follow a surface much more easily than laminar flow. As a result, the laminar flow lines around the top break away from the surface sooner than otherwise, and there is a net upward displacement of the flow lines. The Magnus lift becomes negative. Air exerts a force on any object moving through it. Holding your arm out of the window of a moving car easily illustrates this phenomenon. Aerodynamicists break down the force into two components: lift and drag.

Drag acts to directly oppose motion, whereas lift acts in a direction perpendicular to motion it is usually directed upward in the case of a golf ball. As you rotate your hand in the air stream, you vary the amount and direction of the lift and drag forces acting on your hand. A moving object has a high-pressure area on its front side. Air flows smoothly over the contours of the front side and eventually separates from the object toward the back side.

A moving object also leaves behind a turbulent wake region where the air flow is fluctuating or agitated, resulting in lower pressure behind it. The size of the wake affects the amount of drag on the object. 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. A dimpled ball thus has about half the drag of a smooth ball.

Dimples also affect lift.