Simulations of dolphin kick swimming using smoothed particle hydrodynamics

• Published in: Human movement science 2012-06, Vol.31 (3), p.604-619
• Main Authors: Cohen, Raymond C.Z., Cleary, Paul W., Mason, Bruce R.
• Format: Article
• Language: English
• Subjects: Ankle Joint - physiology; Biological and medical sciences; Biomechanical Phenomena - physiology; Computational fluid dynamics; Computer Simulation; Dolphin kick; Fundamental and applied biological sciences. Psychology; Human swimming; Humans; Hydrodynamics; Image Interpretation, Computer-Assisted; Imaging, Three-Dimensional; Models, Theoretical; Pliability - physiology; Smoothed particle hydrodynamics; Stroke optimisation; Swimming - physiology; Underwater undulatory swimming; Vertebrates: body movement. Posture. Locomotion. Flight. Swimming. Physical exercise. Rest. Sports
• ISSN: 0167-9457; 1872-7646
• DOI: 10.1016/j.humov.2011.06.008

► We model submerged dolphin kick swimming using Smoothed Particle Hydrodynamics. ► The extension kick is responsible for most of the thrust generation. ► Strong vortex ring flow structures are generated by the extension kick. ► Changes in ankle flexibility have negligible impact on net streamwise forces. ► Mean streamwise speed increases linearly with stroke frequency. In competitive human swimming the submerged dolphin kick stroke (underwater undulatory swimming) is utilized after dives and turns. The optimal dolphin kick has a balance between minimizing drag and maximizing thrust while also minimizing the physical exertion required of the swimmer. In this study laser scans of athletes are used to provide realistic swimmer geometries in a single anatomical pose. These are rigged and animated to closely match side-on video footage. Smoothed Particle Hydrodynamics (SPH) fluid simulations are performed to evaluate variants of this swimming stroke technique. This computational approach provides full temporal and spatial information about the flow moving around the deforming swimmer model. The effects of changes in ankle flexibility and stroke frequency are investigated through a parametric study. The results suggest that the net streamwise force on the swimmer is relatively insensitive to ankle flexibility but is strongly dependent on kick frequency.