Baseball is all about fluid dynamics – actually aerodynamics – since the fluid is air.
Aerios: concerning the air.Dynamics: force.The Ancient Greeks coined the term aerodynamics for their study of forces and the resulting motion of objects through air. Today, all the attention a pitcher pays to the placement of his fingers in relation to the seams is done to take advantage of the aerodynamic properties of a ball in flight. Because the seams are the only raised portion of the ball, a baseball made to spin as it moves alternates its smooth and raised surfaces. The cowhide – cut in two peanut-shapes – is smooth.The 216 stitches used to hold the cowhide together, a raised saddle pattern, or double horseshoes, on the ball. These smooth and raised surfaces are the cause of the ball’s performance as it responds to the effects of Lift, Thrust, Drag, and Gravity.
Daniel Bernoulli’s work with fluid mechanics in the 1700’s provides the basis for many of the concepts used in the study of aerodynamics today. According to Bernoulli, an increase in the speed of the fluid occurs in concert with a decrease in pressure or a decrease in the fluid’s gravitational potential energy. That’s why, for a baseball, it’s not only the accuracy and strength of a pitcher’s arm that decides the ball’s path. It’s also the orientation of the stitches as the ball moves through the atmosphere.
But a baseball doesn’t create aerodynamic forces in the same way as the wing on an airplane or other airfoil. The spinning of the ball and the raised surface of the stitches create a whirlpool of rotating air around the ball. This exerts pressure and the ball moves in the direction of least resistance. This Magnus Force is what causes a perfect curve ball to curve right at the plate as the disequilibrium reaches it’s maximum at the end of it’s seconds-long, sixty feet six inch journey.
A successful pitcher knows how to use his arm and wrist to optimal effect. He also knows throwing the ball with the proper speed and arm movement isn’t enough. If his fingers aren’t positioned correctly, there’s no way he can count on the ball to cross the plate where he wants. It all comes down to where he positions his fingers on the ball.