More efficient swimming by spreading your fingers

ORAL

Abstract

A tantalizing question in free-style swimming is whether the stroke efficiency during the pull phase depends on spreading the fingers. It is a subtle effect--not more than a few percent--but it could make a big difference in a race. We measure the drag of arm models with increasing finger spreading in a wind tunnel and compare forces and moments to the results of immersed boundary simulations. Virtual arms were used in the simulations and their 3D-printed real versions in the experiment. We find an optimal finger spreading, accompanied by a marked increase of coherent vortex shedding. A simple actuator disk model explains this optimum.

–

Authors

  • Willem van de Water

    • Applied Physics, Eindhoven University of Technology
    • Eindhoven University of Technology

  • Josje van Houwelingen

    • Applied Physics, Eindhoven University of Technology

  • Dennis Willemsen

    • Applied Physics, Eindhoven University of Technology

  • Wim Paul Breugem

    • Laboratory for Aero and Hydrodynamics, Delft University of Technology

  • Jerry Westerweel

    • Laboratory for Aero and Hydrodynamics, Delft University of Technology

  • Rene Delfos

    • Laboratory for Aero and Hydrodynamics, Delft University of Technology

  • Ernst Jan Grift

    • Laboratory for Aero and Hydrodynamics, Delft University of Technology