Flow Visualisation around Spinning and Non-Spinning Soccer Balls Using the Lattice Boltzmann Method

Takeshi Asai,Hisashi Kai,Atsushi Nakamura,Kaoru Kimachi,Keiko Abe,Sungchan Hong

doi:10.3390/proceedings2060237

Takeshi Asai, Hisashi Kai + Show 4 more

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https://doi.org/10.3390/proceedings2060237

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Publication Date: Feb 12, 2018
Citations: 1	License type: CC BY 4.0

Affiliation: University of Tsukuba, Far Eastern Federal University

Abstract

The drag and lift of footballs have been mainly measured by wind tunnel tests. In the present study, computational fluid dynamics (CFD) and the lattice Boltzmann method were used to visualise the wakes of spinning and non-spinning footballs and analyse the dynamics of the observed vortex structures. The dominant vortex structures in the wakes of the footballs were determined to be large-scale counter-rotating vortex pairs. The fluctuation of the vortex pair for the spinning football was also estimated to be smaller and more stable than that for the non-spinning football. Although the presence of an unstable, large-scale counter-rotating vortex pair in the wake of a non-spinning ball has been previously observed in wind tunnel tests, the present study particularly found that the dominant vortex structure of a spinning ball was a stable, large-scale counter-rotating vortex pair.

Highlights

The drag and lift of non-spinning balls measured in previous studies related to the aerodynamic characteristics of footballs have revealed the existence of a drag crisis [1,2,3]
We investigated the aerodynamic characteristics of a spinning football by computational fluid dynamics (CFD)
The dominant vortex structures in the wake of the balls were observed to consist of large-scale counter-rotating vortex pairs, which were formed in the wake of the balls, with the Cs and Cl of the spinning ball tending to vary less than those of the non-spinning ball

Summary

Introduction

The drag and lift of non-spinning balls measured in previous studies related to the aerodynamic characteristics of footballs have revealed the existence of a drag crisis [1,2,3]. Attempts have been made to measure the aerodynamic characteristics of footballs by free flight tests that closely approximate the actual processes [6,7]. These previous studies mostly involved measurement of the forces such as the drag and lift that act on the ball. Few studies have utilised visualisation and analysis of the flow and vortex structure around the ball, by which the forces acting on the ball are generated [8]. The spinning of a football during a curved shot or pass, as often occurs during competitive football games, is one of the important issues for clarifying the aerodynamic characteristics and the flow and vortex structure around a spinning football

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Conclusion