Aerodynamics simulation of a baseball for predicting pitch trajectory

Abstract

Aerodynamics forces acting on a baseball and its effect on a pitch trajectory of a baseball are numerically investigated. Unsteady computational fluid dynamics is used to obtain the aerodynamic forces acting on the baseball. The pitch trajectory is predicted by solving the equations of the baseball motion with 6 DoF, and the effect of the aerodynamic forces is taken into account by using it as the input to the equations of motion. Two coupling methods are performed in this study. One is “1-way method” which conducts the trajectory simulation after the aerodynamics simulation, the other is “2-way method” which conducts the aerodynamics simulation and the trajectory simulation simultaneously. That is, “2-way method” can consider the interaction between the aerodynamics and the pitch trajectory. “1-way method” simulations are conducted to investigate the effect of back spin speed rotational speed of the baseball on the lift force and drop. The results indicate that the higher rotational speed, the larger lift force and the smaller falling. Concerning the result of “2-way method” simulation, it indicates that the interaction of the motion of the baseball and the aerodynamic drag acting on the baseball affect the velocity change for the direction of flight.