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Research Papers

The Role of the Hand During Freestyle Swimming

[+] Author and Article Information
Raymond C. Z. Cohen

Digital Productivity Flagship,
CSIRO,
Private Bag 33,
Clayton South 3169, VIC, Australia
e-mail: Raymond.Cohen@csiro.au

Paul W. Cleary

Digital Productivity Flagship,
CSIRO,
Private Bag 33,
Clayton South 3169, VIC, Australia
e-mail: Paul.Cleary@csiro.au

Bruce R. Mason

Aquatic Testing, Training and Research Unit,
Australian Institute of Sport,
Leverrier Street,
Bruce 2617, ACT, Australia
e-mail: Bruce.Mason@ausport.gov.au

David L. Pease

Aquatic Testing, Training and Research Unit,
Australian Institute of Sport,
Leverrier Street,
Bruce 2617, ACT, Australia
e-mail: Dave.Pease@ausport.gov.au

1Corresponding author.

Manuscript received December 1, 2014; final manuscript received August 14, 2015; published online October 1, 2015. Assoc. Editor: Francis Loth.

J Biomech Eng 137(11), 111007 (Oct 01, 2015) (10 pages) Paper No: BIO-14-1598; doi: 10.1115/1.4031586 History: Received December 01, 2014; Revised August 14, 2015

The connections between swimming technique and the fluid dynamical interactions they generate are important for assisting performance improvement. Computational fluid dynamics (CFD) modeling provides a controlled and unobtrusive way for understanding the fundamentals of swimming. A coupled biomechanical–smoothed particle hydrodynamics (SPH) fluid model is used to analyze the thrust and drag generation of a freestyle swimmer. The swimmer model was generated using a three-dimensional laser body scan of the athlete and digitization of multi-angle video footage. Two large distinct peaks in net streamwise thrust are found during the stroke, which coincide with the underwater arm strokes. The hand motions generate vortical structures that travel along the body toward the kicking legs and the hands are shown to produce thrust using both lift and drag. These findings advance understanding of the freestyle stroke and may be used to improve athlete technique.

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Figures

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Fig. 1

(a) Laser scanned geometry of the swimmer in an anatomical pose (with blurred facial features). Multi-angle video footage of the swimmer with the animated swimmer mesh overlayed; (b) bottom-up perspective; and (c) side-on perspective taken from a camera above and below the water.

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Fig. 2

Orthogonal views of the finger trajectories in the reference frame of the swimmer

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Fig. 3

Joint speeds in the reference frame of the swimmer: (a) left arm and (b) right arm. The shaded periods correspond to when the arm is in the water and the unshaded periods are the arm recovery.

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Fig. 4

Instantaneous free surface of the fluid during the freestyle swimming simulation

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Fig. 5

Side-on view of the flow around the freestyle swimmer during the right arm pull: (a) fluid in the z = 0.1 plane colored by speed in m/s and (b) fluid in the z = 0.1 plane colored by spanwise vorticity in 1/s

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Fig. 6

Visualization of the flow around the swimmer during the right arm pull. The fluid free surface is colored semitransparent blue whilst the three-dimensional λ2 vortex structures are colored by vorticity magnitude (|ω|) in 1/s. (a) Side view and (b) frontal view from above the pool.

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Fig. 7

Net streamwise forces on the arms of the swimmer: (a) left arm and (b) right arm. The shaded periods correspond to when the hand is in the water and the unshaded periods are the arm recovery.

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Fig. 8

Trajectories of the hands in world coordinates during the freestyle simulations

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Fig. 9

Streamwise velocity of the hands in world coordinates during the freestyle simulations: (a) left hand and (b) right hand. The shaded periods correspond to when the hand is in the water and the unshaded periods are the arm recovery.

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Fig. 10

Angle (α) between the normal to the hand palms and the hand velocity (in world coordinates): (a) left hand and (b) right hand. The shaded periods correspond to when the hand is in the water and the unshaded periods are the arm recovery.

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