Influence of a postural change of the swimmer's head in hydrodynamic performances using 3D CFD

Popa, Cătălin; Arfaoui, A.; Fohanno, S.; Taı̈ar, Redha; Polidori, Guillaume

doi:10.1080/10255842.2012.683429

Cited by 18 publications

(14 citation statements)

References 13 publications

(24 reference statements)

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“…Because of the nonuniformity of the body on the swimmer's head, shoulders, elbows, hips, knees, and buttocks, complex turbulent zones are Computational Fluid Dynamics Method for the Analysis of the Hydrodynamic Performance in Swimming http://dx.doi.org/10.5772/61176 generated around the swimmer's body. In this study, Popa et al [26] noted a recirculation zone on the swimmer's buttocks with a larger recirculation zone when the head is lifted up whatever the head position. The numerical results show that the position of the head plays a very important role for high swimming velocities on the hydrodynamic performances.…”

Section: Streamline Patternsmentioning

confidence: 48%

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Computational Fluid Dynamics Method for the Analysis of the Hydrodynamic Performance in Swimming

Arfaoui¹,

Polidori²

2015

Mass Transfer - Advancement in Process Modelling

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Numerical simulations of the flow around a swimmer during the different swimming phases were carried out to understand the drag force. In mechanics of swimming, the reduction of forces, which oppose to the swimmers advancement, plays a very important part in the improvement of the performances. As a consequence, the performance improvement requires a better understanding of the structure of the fluid flow around swimmers and a good knowledge of the pressure fields and wall shear stress encountered to minimize them. This chapter will focus on computational fluid dynamics (CFD) procedures and results for this practical implication in swimming and will aim at highlighting details on numerical schemes, validations, and results showing the way CFD can be used as a powerful tool in swimming understanding.

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Section: Streamline Patternsmentioning

confidence: 48%

“…Popa et al [26] showed in Figure 11 streamline patterns to highlight the flow structure around the swimmer's neck, chin, and buttocks for each of the three head positions and for a velocity of 3.1 m/s. One may observe recirculation zones around the swimmer's neck, chin, and buttocks according to the position of the head.…”

Section: Streamline Patternsmentioning

confidence: 99%

Computational Fluid Dynamics Method for the Analysis of the Hydrodynamic Performance in Swimming

Arfaoui¹,

Polidori²

2015

Mass Transfer - Advancement in Process Modelling

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“…During these phases, the position of the head is of fundamental importance because it determines the dynamics of the impact of the body with the fluid and the vortexes that propagate along the swimmer's body (9,10,15). Swim caps could affect these factors and thus could have an impact on swimming performance (5).…”

Section: Discussionmentioning

confidence: 99%

“…Studies using computational fluid dynamics indeed have shown that the position of the head has a marked influence on Dp, strongly modifying the wake around the swimmer (9,10,15). Moreover, Marinho et al (5) have shown that a reduction of Dp of up to 15% can be obtained by wearing a swim cap (compared with the "no-cap" condition), even if this "intervention" affects a very small surface of the swimmer's body.…”

Section: Introductionmentioning

confidence: 96%

Effect of Swim Cap Model on Passive Drag

Gatta

Zamparo²,

Cortesi³

2013

Journal of Strength and Conditioning Research

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Hydrodynamics plays an important role in swimming because even small decreases in a swimmer's drag can lead to performance improvements. During the gliding phases of a race, the head of a swimmer is an important point of impact with the fluid, and the swim cap, even if it covers only a small portion of the swimmer's body, can have an influence on drag. The purpose of this study was to investigate the effects on passive drag (Dp) of wearing 3 different types of swim caps (LSC: a lycra cap; CSC: a silicone cap; HSC: a silicone helmet cap without seams). Sixteen swimmers were tested at 3 velocities (1.5, 1.7, 1.9 m·s), and the Dp measurements were repeated at each condition 5 times. A statistical analysis revealed significant differences in drag (p < 0.01) among caps: Dp is 5-6.5% lower for HSC than for CSC at all speeds and 6% lower in HSC than CSC at 1.9 m·s. No differences in Dp were observed between LSC and CSC at all speeds. Thus, the differences in Dp are based on the type of material (lycra vs. silicone) and on the presence/lack of seams: the HSC swim cap is the most rigid, the most adherent to the swimmer's head, and does not allow the formation of wrinkles compared with the other 2 investigated swim caps. Therefore, the following conclusions can be made: (a) swimmers should take care when selecting their swim cap if they want to improve the fluid dynamics at the "leading edge" of their body and (b) because Dp is affected by the swim cap model, care should be taken when comparing data from different studies, especially at faster investigated speeds.

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“…In swimming, this methodology has been used to study the propulsive forces produced by the hands and forearms [8][9][10] and the legs during swimming, 11,12 as well as the magnitude of the drag forces resisting forward motion. [13][14][15] With respect to propulsive forces, CFD can provide insight into basic issues concerning swimming technique that, based on the knowledge provided by experimental approaches, remain unclear or, at least, controversial. The relative position of the fingers and thumb during the underwater path of the stroke cycle is one of these issues.…”

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confidence: 99%

Hydrodynamic Analysis of Different Finger Positions in Swimming: A Computational Fluid Dynamics Approach

Vilas-Boas

Ramos

Fernandes

et al. 2015

Journal of Applied Biomechanics

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The aim of this research was to numerically clarify the effect of finger spreading and thumb abduction on the hydrodynamic force generated by the hand and forearm during swimming. A computational fluid dynamics (CFD) analysis of a realistic hand and forearm model obtained using a computer tomography scanner was conducted. A mean flow speed of 2 m · s(-1) was used to analyze the possible combinations of three finger positions (grouped, partially spread, totally spread), three thumb positions (adducted, partially abducted, totally abducted), three angles of attack (a = 0°, 45°, 90°), and four sweepback angles (y = 0°, 90°, 180°, 270°) to yield a total of 108 simulated situations. The values of the drag coefficient were observed to increase with the angle of attack for all sweepback angles and finger and thumb positions. For y = 0° and 180°, the model with the thumb adducted and with the little finger spread presented higher drag coefficient values for a = 45° and 90°. Lift coefficient values were observed to be very low at a = 0° and 90° for all of the sweepback angles and finger and thumb positions studied, although very similar values are obtained at a = 45°. For y = 0° and 180°, the effect of finger and thumb positions appears to be much most distinct, indicating that having the thumb slightly abducted and the fingers grouped is a preferable position at y = 180°, whereas at y = 0°, having the thumb adducted and fingers slightly spread yielded higher lift values. Results show that finger and thumb positioning in swimming is a determinant of the propulsive force produced during swimming; indeed, this force is dependent on the direction of the flow over the hand and forearm, which changes across the arm's stroke.

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Influence of a postural change of the swimmer's head in hydrodynamic performances using 3D CFD

Cited by 18 publications

References 13 publications

Computational Fluid Dynamics Method for the Analysis of the Hydrodynamic Performance in Swimming

Computational Fluid Dynamics Method for the Analysis of the Hydrodynamic Performance in Swimming

Effect of Swim Cap Model on Passive Drag

Hydrodynamic Analysis of Different Finger Positions in Swimming: A Computational Fluid Dynamics Approach

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