Numerical study of the movement of the knuckleball with rifle spin
摘要
In this study, the flow around the knuckleball with rifle spin is numerically simulated by solving the incompressible Navier-Stokes equations and computed the aerodynamics coefficients (i.e. drag, lift and side force coefficients) of the ball by using the results of flow calculations. These coefficients are computed for the different positions of the seam on the ball. The effect of this position and the rotation speed of the ball on the orbit are investigated. From the computations, we obtain numerically the "irregular change of the orbit" which is the most remarkable feature of the knuckleball. Also we find this feature appears even if the ball rotates several times per second suggesting the potential of the knuckleball with rifle spin which may be easier to throw than the ordinal knuckleball.