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Dimples exist on golf balls for a very good reason.  The efect of dimples were actually discovered accidentally, when it was discovered that rough surface, scarred balls traveled further than smooth ones. Ball makers than began to intentionally put dimples on balls to produce the same effect of rough surface balls.

There are two components to drag.  One is frictional drag, but the other is due to pressure drag.  Frictional drag is due to shear stresses on the object.  Pressure drag is due to pressure differences between the front and rear of the object due to boundary layer separation from the surface of the ball.

For streamlined bodies, the drag is mostly due to frictional drag and it is beneficial to have smooth surfaces to promote laminar flow.  However, for blunt bodies like golf balls, drag is mostly due to pressure differences.

For a smooth surface, the boundary layer has less energy and separates from the ball earlier.  The rear just has a wake region that has decreased pressure. A dimpled ball promotes turbulent boundary layer flow.  A turbulent boundary layer has more energy and thus travels further along the surface before separating from the ball.  A dimpled ball thus has less pressure reduction at the rear, and overall less drag.

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