ジャイロ回転する野球ボールのスパコンによる空力解析

Abstract

The aerodynamics of baseballs with gyro spins and their influences on the flight trajectories are studied. We use a simulation code based on Lattice Boltzmann Method with the cumulant collision term which works for a LES model. We analyze 2- and 4-seam orientations for gyro-spin balls according to the actual MLB pitches. Both results exhibit periodicity of lift forces. We also compute 2- and 4-seam orientations for back-spin according to compare them with the gyro-spin balls. In the case of back-spin balls, both exhibit longitudinal lift forces because of the magnus effect. In the case of gyro-spin, the time-averaged lift forces are almost zero. The trajectory of above 4 kinds of rotation is studied and the longitudinal displacement of the gyro-spin ball is largest among them. It is understood that aerodynamics of back-spin and gyro-spin balls are quite different, and the seam orientations have strong effects on the aerodynamic and flight trajectories.