Aerodynamic forces on projectiles used in various sports

Shah, Kunjal; Shakya, Ravi; Mittal, Sanjay

doi:10.1063/1.5064700

Cited by 18 publications

(16 citation statements)

References 36 publications

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“…The critical region (1.65 × 10 5 < Re < 1.75 × 10 5 ) is marked in Figure 3. The non-dimensional side force coefficients for CS (CZ~0.3) are comparable with the results of other studies on stationary balls [9,10]. Note that the magnitude of CZ for RS is less than that for CS either side of the critical Re (Recrit).…”

Section: Flow Separation On Spheres and Cricket Ballssupporting

confidence: 87%

“…They found that the critical flow regime can be further categorized into three sub-regimes based on the nature of the LSB. The method of PIV has not been used to identify the LSB on a cricket ball (rotating or nonrotating), but it has been used to show the boundary layer separation angles on a stationary sphere with a trip at the sub-critical and critical flow regimes, demonstrating CS and RS [10]. The image resolution of their system was too low to be able to resolve an LSB.…”

Section: Flow Separation On Spheres and Cricket Ballsmentioning

confidence: 99%

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Investigation of Reverse Swing and Magnus Effect on a Cricket Ball Using Particle Image Velocimetry

et al. 2020

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Lateral movement from the principal trajectory, or “swing”, can be generated on a cricket ball when its seam, which sits proud of the surface, is angled to the flow. The boundary layer on the two hemispheres divided by the seam is governed by the Reynolds number and the surface roughness; the swing is fundamentally caused by the pressure differences associated with asymmetric flow separation. Skillful bowlers impart a small backspin to create gyroscopic inertia and stabilize the seam position in flight. Under certain flow conditions, the resultant pressure asymmetry can reverse across the hemispheres and “reverse swing” will occur. In this paper, particle image velocimetry measurements of a scaled cricket ball are presented to interrogate the flow field and the physical mechanism for reverse swing. The results show that a laminar separation bubble forms on the non-seam side (hemisphere), causing the separation angle for the boundary layer to be increased relative to that on the seam side. For the first time, it is shown that the separation bubble is present even under large rates of backspin, suggesting that this flow feature is present under match conditions. The Magnus effect on a rotating ball is also demonstrated, with the position of flow separation on the upper (retreating) side delayed due to the reduced relative speed between the surface and the freestream.

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Section: Flow Separation On Spheres and Cricket Ballssupporting

confidence: 87%

Section: Flow Separation On Spheres and Cricket Ballsmentioning

confidence: 99%

Investigation of Reverse Swing and Magnus Effect on a Cricket Ball Using Particle Image Velocimetry

et al. 2020

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Section: Resultsmentioning

confidence: 99%

“…The non-dimensional side force data in the study by Shah et al 23 can be compared with the ‘new ball’ data the authors presented above. Over the range for CS (1.3 × 10 5 < Re < 1.7 × 10 5 ) Shah et al 23 measured a relatively constant C Z = 0.3, which agrees well with the data presented in Figure 10(b). The comparison is good despite differences in the seam angle to the flow (30° for Shah et al 23 ) versus 15° used here; also, the ball used in the study by Shah et al 23 was manufactured by SG , not Dukes .…”

Section: Resultsmentioning

confidence: 99%

Practical perspective of cricket ball swing

Scobie

Shelley

Jackson

et al. 2019

Proceedings of the Institution of Mechanical Engineers, Part P:

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A cricket ball has an encircling, stitched seam proud from the leather, separating the surface into two distinct hemispheres. When angled, this seam is exploited by the skilful bowler to create an asymmetry in the viscous boundary layer and the ball will swing. In this article, the fluid dynamics of both conventional swing and reverse swing are explained and demonstrated. Using balls worn under match conditions and insight from a professional cricketer, factors affecting swing were tested experimentally in a wind tunnel. The surface condition of the ball was demonstrated to have a substantial effect on the amount of swing: conventional swing was most obvious for a new, polished cricket ball and the swing reduced as the ball accumulated wear as would happen as the match progresses; reverse swing was seen at high bowling speeds with a worn ball. Humidity in isolation was shown to have no significant effect on swing, dispelling a long-standing myth in the cricketing community. A grid was used to simulate atmospheric convective micro-turbulence above a cricket pitch on a hot day without cloud cover; strong evidence suggested that turbulence inhibits the fragile conditions necessary for laminar flow and prevents swing.

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“…They have been employed for measurement of time-varying forces by a number of researchers (Suryanarayana & Prabhu 2000; Deshpande et al. 2017; Shah, Shakya & Mittal 2019). The balance was installed inside the horizontal sting and connected directly to the rear part of the sphere.…”

Section: Experimental Set-up and Methodologymentioning

confidence: 99%

Effect of free stream turbulence on the topology of laminar separation bubble on a sphere

Desai

Mittal

2022

J. Fluid Mech.

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The topology of a laminar separation bubble (LSB) on a sphere in the critical regime is investigated via experiments at five turbulent intensities: $T_u=0.06\,\%$ , $0.42\,\%$ , $0.71\,\%$ , $1.00\,\%$ and $1.36\,\%$ . The drag crisis occurs at a lower $Re$ and becomes gradual with increasing $T_u$ . The flow is devoid of the LSB at the onset of the critical regime. It forms on a small part of the sphere and not at all azimuthal locations, early in the critical regime. The LSB forms at more azimuthal locations with increasing $Re$ . This azimuthal expansion of the LSB is accompanied by intermittency for a small range of $Re$ . Towards the end of the critical regime, an axisymmetric LSB forms on the sphere at all time instants. A model is proposed to estimate the azimuthal extent and distribution of the LSB from the mean force coefficients of a flow state. The model predicts that the LSB forms as multiple segments for a large part of the critical regime. During the spatial growth of the LSB with $Re$ in the critical regime, some of its fragments relocate to alternate locations. Moderate increase in $T_u$ ( $0.42\,\% \leq T_u \leq 0.71\,\%$ ) leads to rich dynamics with several intermittent flow states. However, fewer intermittent states are observed beyond a certain $T_u$ ( ${\geq }1.00\,\%$ ).

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Aerodynamic forces on projectiles used in various sports

Cited by 18 publications

References 36 publications

Investigation of Reverse Swing and Magnus Effect on a Cricket Ball Using Particle Image Velocimetry

Investigation of Reverse Swing and Magnus Effect on a Cricket Ball Using Particle Image Velocimetry

Practical perspective of cricket ball swing

Effect of free stream turbulence on the topology of laminar separation bubble on a sphere

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