Golf balls have dimples primarily to improve their aerodynamic properties, which significantly affects wind resistance, flight trajectory, and distance.
Wind Resistance: The dimples on a golf ball create a thin turbulent boundary layer of air that clings to the ball's surface. This turbulent layer reduces the wake (the low-pressure area behind the ball), which in turn decreases drag or wind resistance. A smooth ball would experience more drag because the airflow would separate earlier, creating a larger wake.
Flight Trajectory: By reducing drag, dimples allow the ball to travel more smoothly through the air. Additionally, the dimples help generate lift by influencing the airflow around the ball, especially when the ball is spinning. This lift helps the ball stay in the air longer, contributing to a higher and more stable flight trajectory.
Distance: With reduced drag and increased lift, a dimpled golf ball can travel much farther than a smooth ball. The dimples optimize the balance between lift and drag, enabling the ball to cover greater distances.
Number of Dimples: The number of dimples on a golf ball typically ranges from about 300 to 500. This number affects the ball's aerodynamic behavior. More dimples can increase the turbulent boundary layer effect, reducing drag further but also potentially increasing surface roughness, which can affect control.
Optimal Number for Long Distance: There isn't a single "best" number of dimples universally agreed upon, as design depends on the balance between distance, control, and feel. However, many long-distance golf balls have around 300 to 400 dimples, designed to maximize lift and minimize drag for optimal distance.
In summary, dimples are crucial for reducing wind resistance, improving flight stability, and maximizing the distance a golf ball can travel. A golf ball without dimples will have a lower, less stable trajectory and will not travel as far as a dimpled ball. The number and pattern of dimples are carefully engineered to optimize these aerodynamic effects.