Transient simulation of a four-seam fastball pitch

A transient RANS simulation with dynamic mesh was conducted on a rotating, translating baseball in order to quantify the resulting lift, drag, and moment on the baseball. The simulated pitch is a four-seam fastball, so named because the batter sees four seams for each rotation of the ball. This pitch is design for high speed and lift production to counteract gravity and keep the trajectory straight. As the ball rotates, the seam position moves and creates different flow structures for each angle of rotation. The separation points and wake vortical structures are studied for different baseball orientations. Coefficients of drag, lift, and moment about the rotation axis are calculated relative to rotation angle. These forces are integrated to calculate the trajectory of the pitch. The detailed flow structures around the threads of the seam are also analyzed.