Magnus effect on a rotating sphere at high Reynolds numbers

Kray, Thorsten; Joerg, Franke; Frank, Wolfram

doi:10.1016/j.jweia.2012.07.005

Cited by 41 publications

(16 citation statements)

References 35 publications

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“…It is interesting to note that there are visible side forces acting on both models in this Reynolds number regime even in the time-averaged sense. Similar features were also observed in the experimental measurements of flows past rotating smooth spheres by Kray et al [15]. This may imply that the negative Magnus effect exhibits somewhat three-dimensional characteristics.…”

Section: Resultssupporting

confidence: 87%

Numerical Investigation of the Flow Past a Rotating Golf Ball and Its Comparison with a Rotating Smooth Sphere

Tsubokura

Tsunoda

2017

Flow Turbulence Combust

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Large-eddy simulations are conducted for a rotating golf ball and a rotating smooth sphere at a constant rotational speed at the subcritical, critical and supercritical Reynolds numbers. A negative lift force is generated in the critical regime for both models, whereas positive lift forces are generated in the subcritical and supercritical regimes. Detailed analysis on the flow separations on different sides of the models reveals the mechanism of the negative Magnus effect. Further investigation of the unsteady aerodynamics reveals the effect of rotating motion on the development of lateral forces and wake flow structures. It is found that the rotating motion helps to stabilize the resultant lateral forces for both models especially in the supercritical regime.

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Section: Resultssupporting

confidence: 87%

Numerical Investigation of the Flow Past a Rotating Golf Ball and Its Comparison with a Rotating Smooth Sphere

Tsubokura

Tsunoda

2017

Flow Turbulence Combust

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“…It can be noted that beyond α = 1.5, there is very slight increase in the time-averaged displacement, suggesting that the magnitude of the Magnus force is limited. Similar behaviour has also been observed in previous studies of rigidly mounted rotating spheres by Macoll (1928), Barlow & Domanski (2008), Kray et al (2012) and Kim et al (2014), showing that the increase in the lift coefficient of a sphere reaches a plateau as α is increased to a certain value, which depends on the Reynolds number. Figure 12 shows logarithmic-scale power-spectrum plots depicting the dominant oscillation frequency content ( f * = f /f nw ) as a function of reduced velocity for both the non-rotating case (α = 0) and the rotating case (α = 1).…”

Section: Effect Of Rotation On the Vibration Responsesupporting

confidence: 88%

“…On the other hand, there have been some experimental studies conducted at considerably higher Reynolds numbers (Re 6 × 10 4 ) that focus mainly on the effect of transverse rotation on the fluid forces, e.g. the inverse Magnus effect (Macoll 1928;Barlow & Domanski 2008;Kray, Franke & Frank 2012;Kim et al 2014), where the rotation-induced lift suddenly changes direction as the Reynolds number is increased. It is still unknown if the rotation suppresses vortex shedding at such high Reynolds numbers.…”

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confidence: 99%

Vortex-induced vibration of a rotating sphere

et al. 2017

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OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. Vortex-induced vibration (VIV) of a sphere represents one of the most generic fundamental fluid-structure interaction problems. Since vortex-induced vibration can lead to structural failure, numerous studies have focused on understanding the underlying principles of VIV and its suppression. This paper reports on an experimental investigation of the effect of imposed axial rotation on the dynamics of vortex-induced vibration of a sphere that is free to oscillate in the cross-flow direction, by employing simultaneous displacement and force measurements. The VIV response was investigated over a wide range of reduced velocities (i.e. velocity normalised by the natural frequency of the system): 3 U * 18, corresponding to a Reynolds number range of 5000 < Re < 30 000, while the rotation ratio, defined as the ratio between the sphere surface and inflow speeds, α = |ω|D/(2U), was varied in increments over the range of 0 α 7.5. It is found that the vibration amplitude exhibits a typical inverted bell-shaped variation with reduced velocity, similar to the classic VIV response for a non-rotating sphere but without the higher reduced velocity response tail. The vibration amplitude decreases monotonically and gradually as the imposed transverse rotation rate is increased up to α = 6, beyond which the body vibration is significantly reduced. The synchronisation regime, defined as the reduced velocity range where large vibrations close to the natural frequency are observed, also becomes narrower as α is increased, with the peak saturation amplitude observed at progressively lower reduced velocities. In addition, for small rotation rates, the peak amplitude decreases almost linearly with α. The imposed rotation not only reduces vibration amplitudes, but also makes the body vibrations less periodic. The frequency spectra revealed the occurrence of a broadband spectrum with an increase in the imposed rotation rate. Recurrence analysis of the structural vibration response demonstrated a transition from periodic to chaotic in a modified recurrence map complementing the appearance of broadband spectra at the onset of bifurcation. Despite considerable changes in flow structure, the vortex phase (φ vortex ), defined as the phase between the vortex force and the body displacement, follows the same pattern as for the non-rotating case, with the φ vortex increasing gradually from low values in Mode I of the sphere vibration to almost 180• as the system undergoes a continuous transition to Mode II of the sphere vibration at higher reduced velocity. The total phase (φ total ), defined as the phase between the transverse lift force and the body displacement, only increases from low values after the peak amplitude † Email address for correspondence: jisheng.zhao@monash.edu response in Mode II has been reached. It reaches its maximum value (∼165• ) close to the transition from the Mode II upper plateau t...

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“…where ρ (= 1.2 kg/m 3 ) represents air density, S (= 4.3 × 10 −3 m 2 ) is the sectional area of the ball, and V is the velocity magnitude. C d (= 0.35) and C l (= (πS) 0.5 × spin rate/2) are the drag coefficient and lift coefficient, respectively, which are the same as those reported in (Kray et al, 2012). When the spin axis of the ball is perpendicular to the traveling direction, the drag increases as the speed of the ball increases, and the lift increases as the rotation speed increases.…”

Section: Simulation Analysismentioning

confidence: 77%

Influence of Release Parameters on Pitch Location in Skilled Baseball Pitching

Kusafuka

Kobayashi

Miki

et al. 2020

Front. Sports Act. Living

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This study explored the mechanical factors that determine accuracy of a baseball pitching. In particular, we focused on the mechanical parameters at ball release, referred to as release parameters. The aim was to understand which parameter has the most deterministic influence on pitch location by measuring the release parameters during actual pitching and developing a simulation that predicts the pitch location from given release parameters. By comparing the fluctuation of the simulated pitch location when varying each release parameter, it was found that the elevation pitching angle and speed significantly influenced the vertical pitch location, and the azimuth pitching angle significantly influenced the horizontal pitch location. Moreover, a regression model was obtained to predict the pitch location, and it became clear that the significant predictors for the vertical pitch location were the elevation pitching angle, the speed, and spin axis, and those for the horizontal pitch location were the azimuth pitching angle, the spin axis, and horizontal release point. Therefore, it was suggested that the parameter most affecting pitch location weas pitching angle. On the other hand, multiple regression analyses revealed that the relation between release parameters varied between pitchers. The result is expected to contribute to an understanding of the mechanisms underlying accurate ball control skill in baseball pitching.

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Magnus effect on a rotating sphere at high Reynolds numbers

Cited by 41 publications

References 35 publications

Numerical Investigation of the Flow Past a Rotating Golf Ball and Its Comparison with a Rotating Smooth Sphere

Numerical Investigation of the Flow Past a Rotating Golf Ball and Its Comparison with a Rotating Smooth Sphere

Vortex-induced vibration of a rotating sphere

Influence of Release Parameters on Pitch Location in Skilled Baseball Pitching

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