Sports ball aerodynamics: A numerical study of the erratic motion of soccer balls

Abstract

The application of the commercial CFD code, FLUENT, to sports ball aerodynamics was assessed and a validated 3D analysis technique was established for balls that have been scanned with a 3D laser scanner or drawn in CAD. The technique was used to examine the effects of surface geometry on the aerodynamic behaviour of soccer balls by comparing the flow around different balls and predicting the aerodynamic force coefficients. The validation process included performing CFD studies on 3D smooth spheres and various soccer balls, and comparing the results to wind tunnel tests and flow visualisation.The CFD technique used a surface wrapping meshing method and the Reynolds-Averaged NavierStokes approach with the realizable k-ε turbulence model, which was found to be able to predict the drag, lift and side force coefficients (C D , C L and C S ) reliably, to compare the wake behaviour, and to give good pressure distributions near the stagnation point. The main limitations of the technique with the available computational resources were its inability to accurately predict boundary layer transition or growth, but despite this, several conclusions could be drawn regarding soccer ball aerodynamics. C D was not significantly different between balls. C L and C S were found to be significantly affected by the orientation of the ball relative to its direction of travel, meaning that balls kicked with low amounts of spin could experience quasi-steady lift and side forces and move erratically from side-to-side or up and

The effect of surface geometry on soccer ball trajectories

“…It can be seen that Re varied from 2.15 9 10 5 to 3.18 9 10 5 (2.67 9 10 5 ± 19%), compared to the average measured Re of 3.56 9 10 5 in the player testing. The C D values were of the expected order of magnitude, but increased sharply with Re, contrary to results from the other studies [3,4] and the expected trend. Previous wind tunnel tests on a spinning scale model soccer ball [19] showed a drop in C D in this Reynolds number regime.…”

“…11, together with the corresponding wind tunnel measurements [4] and CFD simulations [3]. The results showed a large amount of scatter and it was difficult to distinguish between the balls.…”

“…This is mainly because they are difficult to mount and fit in wind tunnels and because the combination of topspin and sidespin, which is frequently applied to them, produces swerving and dipping trajectories that are difficult to measure accurately. Recent wind tunnel experiments and CFD studies have revealed some interesting phenomena related to the unsteady flight of soccer balls launched with low or zero spin [3,4]. It was found that such trajectories could swerve significantly several times in the air due to the asymmetry of the seam patterns.…”

CFD Study of Drag and Lift of Sepak Takraw Ball at Different Face Orientations

“…Considering the complex geometry of the ball limits the capability to run simulation of rotating condition which requires a significant computational overhead; therefore nonrotating condition was chosen as almost all aerodynamic sports research started with nonrotating condition [2,7,12,16]. All different positions are defined as shown in Figure 2.…”

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

“…Computational fluid dynamics (CFD) can be used to visualise and analyse the flow and vortex structure around a bluff body, especially a steady-state analysis using turbulence models such as the k-ε model [9,10]. Nevertheless, a method for applying CFD to unsteady-state analysis using the lattice Boltzmann method was more recently developed.…”