Flow Visualization of Spinning and Nonspinning Soccer Balls Using Computational Fluid Dynamics

Takeshi Asai,Sungchan Hong,Yasumi Nakanishi,Nakaba Akiyama

doi:10.3390/app10134543

Abstract

Various studies have been conducted on the aerodynamic characteristics of nonspinning and spinning soccer balls. However, the vortex structures in the wake of the balls are almost unknown. One of the main computational fluid dynamics methods used for the analysis of vortex structures is the lattice Boltzmann method as it facilitates high-precision analysis. Studies to elucidate the dominant vortex structure are important because curled shots and passes involving spinning balls are frequently used in actual soccer games. In this study, we identify the large-scale dominant vortex structure of a soccer ball and investigate the stability of the structure using the lattice Boltzmann method, wind tunnel tests, and free-flight experiments. One of the dominant vortex structures in the wake of both nonspinning and spinning balls is a large-scale counter-rotating vortex pair. The side force acting on a spinning ball stabilizes when the fluctuation of the separation points of the ball is suppressed by the rotation of the ball. Thus, although a spinning soccer ball is deflected by the Magnus effect, its trajectory is regular and stable, suggesting that a spinning ball can be aimed accurately at the outset of its course.

Highlights

The behavior of sports balls is known to be significantly affected by aerodynamic characteristics such as drag and lift [1,2], and various studies have been conducted to investigate the effect of these characteristics [3,4,5,6,7,8,9]
Many studies have previously been conducted on the vortex structure of a smooth sphere [12,13,14], and the results indicate that a horseshoe vortex, an alternating vortex, or a helical vortex is formed depending on the Reynolds number [15,16,17,18]
We investigated the aerodynamic characteristics and large-scale dominant vortex structure of a soccer ball using a combination of the lattice Boltzmann method, wind tunnel tests, and free-flight experiments

Summary

Introduction

The behavior (e.g., the trajectory) of sports balls is known to be significantly affected by aerodynamic characteristics such as drag and lift [1,2], and various studies (including wind tunnel experiments) have been conducted to investigate the effect of these characteristics [3,4,5,6,7,8,9]. Various studies have been conducted on the aerodynamics of soccer balls. A drag crisis occurs under certain conditions during the drag and lift measurements of nonspinning balls for which wind tunnel experiments are relatively easy to set up [19].

Methods

Results

Conclusion