Format

Send to

Choose Destination
See comment in PubMed Commons below
J Theor Biol. 2012 Sep 7;308:141-6. doi: 10.1016/j.jtbi.2012.05.033. Epub 2012 Jun 9.

The constructal-law physics of why swimmers must spread their fingers and toes.

Author information

  • 1Université de Toulouse, INSA, Laboratoire Matériaux et Durabilité des Constructions, 135, Avenue de Rangueil, F-31077 Toulouse Cedex 04, France.

Abstract

Here we show theoretically that swimming animals and athletes gain an advantage in force and speed by spreading their fingers and toes optimally. The larger force means larger body mass lifted and greater speed, in accord with the constructal theory of all animal locomotion. The spacing between fingers must be twice the thickness of the boundary layer around one finger. This theoretical prediction is confirmed by computational fluid dynamics simulations of flow across two and four cylinders of diameter D. The optimal spacing is in the range 0.2D-0.4D, and decreases slightly as the Reynolds number (Re) increases from 20 to 100. For example, the total force exerted by two optimally spaced cylinders exceeds by 53% the total force of two cylinders with no spacing when Re=20. These design features hold for both time-dependent and steady-state flows.

Copyright © 2012 Elsevier Ltd. All rights reserved.

[PubMed - indexed for MEDLINE]
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Elsevier Science
    Loading ...
    Write to the Help Desk