Wind tunnel measurement and flow visualisation of soccer ball knuckle effect

Murakami, Masahide; Seo, Kazuya; Kondoh, Masakazu; Iwai, Yuki

doi:10.1007/s12283-012-0085-8

Cited by 8 publications

(6 citation statements)

References 6 publications

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“…The vortex pairs in the wake of the spinning ball (curve) tended to be stable, whereas those in the wake of the non-spinning or slowly spinning ball tended to be unstable, exhibiting large fluctuations such as rotation about the axis in the motion direction and breakdown. These instabilities are considered to be one of the causes of the knuckling effect observed in nonspinning and slowly spinning balls [17][18][19]. In addition, the deviation of side force coefficient of the spinning ball determined by CFD tended to be smaller than that of the non-spinning ball.…”

Section: Discussionmentioning

confidence: 99%

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

Asai

Hong

Kimachi

et al. 2018

The 12th Conference of the International Sports Engineering Association

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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.

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Section: Discussionmentioning

confidence: 99%

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

Asai

Hong

Kimachi

et al. 2018

The 12th Conference of the International Sports Engineering Association

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“…Texier calculated that the force produced by the vortices at Strohual numbers (St) of St∼ 0.2 is significantly lower than the magnitude of the lift measured in experiments, so that it practically does not contribute to lift. More information about lift force in ball sports can be found in investigations by Mehta [12], Hong et al [42], and Murakami et al [43].…”

Section: The Lift and Side Forcesmentioning

confidence: 99%

On the Aerodynamic Forces on a Baseball, With Applications

Santos

Aguirre-López

Díaz-Hernández

et al. 2019

Front. Appl. Math. Stat.

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“…For example, the effects of dimple shape and the spin on the flying distance of golf ball were studied [1,2] and the influence of seams and rotation on the aerodynamic properties were investigated for baseball [3,4]. Furthermore, the aerodynamic characteristics were evaluated for soccer balls [5][6][7][8][9][10][11][12]. In the past, the aerodynamic properties of sports ball were studied by wind-tunnel experiments, which allow the evaluation of time-averaged statistics of the sports ball in high accuracy [7,12].…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, the aerodynamic characteristics were evaluated for soccer balls [5][6][7][8][9][10][11][12]. In the past, the aerodynamic properties of sports ball were studied by wind-tunnel experiments, which allow the evaluation of time-averaged statistics of the sports ball in high accuracy [7,12]. Although such wind tunnel studies provide fundamental information on the aerodynamic properties acting on the sports balls, it is difficult to evaluate the unsteady aerodynamic properties of kicked soccer ball.…”

Section: Introductionmentioning

confidence: 99%

“…Then, the irregular flight trajectories such as curves, falls, or unsteady movements were observed more frequently than before. These changes in the flight trajectory of a soccer ball are called knuckle effects, and the aerodynamic performance has been studied in wind tunnel [7,12]. The experimental studies suggest the transition of the flow around a soccer ball from subcritical to supercritical at lower Reynolds number than that of the smooth sphere [7].…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of Flight Trajectory and Unsteady Fluid Forces on Kicked Non-Spinning Soccer Ball by Digital Image Analysis

Yamagata¹,

Nagasawa²,

Fujisawa³

et al. 2013

JFCMV

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This paper describes the experimental method for evaluating the flight trajectory and the aerodynamic performance of a kicked non-spinning soccer ball. The flight trajectory measurement is carried out using the digital image analysis. A centroid method and a template matching method are tested for the flight trajectory analysis using the artificial images generated by the data of a free-fall experiment. The drag coefficient obtained by the centroid method is better suited for the sports ball experiment than that by the template matching method, which is due to the robustness of the centroid method to the non-uniform illumination. Then, the flight trajectory analysis is introduced to a kicked experiment for a non-spinning soccer ball. The experimental result obtained from the stereo observation indicates that the S-shaped variation is found in the three-dimensional flight trajectory and in the side force coefficient during the flight of the nonspinning soccer ball.

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Wind tunnel measurement and flow visualisation of soccer ball knuckle effect

Cited by 8 publications

References 6 publications

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

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

On the Aerodynamic Forces on a Baseball, With Applications

Evaluation of Flight Trajectory and Unsteady Fluid Forces on Kicked Non-Spinning Soccer Ball by Digital Image Analysis

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