Conventional vs. Reverse Swing
In conventional swing with a new ball, the seam trips laminar airflow into a turbulent boundary layer on one side, causing the ball to swing toward the rough side.
In reverse swing—occurring after 35+ overs of wear—both sides have turbulent boundary layers. The rough side's thicker turbulent boundary layer separates earlier, while the smoother side's boundary layer remains attached longer, pulling the ball sharply toward the shiny side late in its trajectory.
