Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

If you need an accessible version of this item please contact JSTOR User Support

The Menace of Momentum: Dynamic Forces on Flexible Organisms

Mark Denny, Brian Gaylord, Brian Helmuth and Tom Daniel
Limnology and Oceanography
Vol. 43, No. 5 (Jul., 1998), pp. 955-968
Stable URL: http://www.jstor.org/stable/2839189
Page Count: 14
  • Get Access
  • More info
  • Cite this Item
If you need an accessible version of this item please contact JSTOR User Support
The Menace of Momentum: Dynamic Forces on Flexible Organisms
Preview not available

Abstract

It has been proposed that the mechanical flexibility of many waver-swept organisms reduces the hydrodynamic forces imposed on these plants and animals. For example, reorientation of the organism can render it more streamlined, and by "going with the flow" a flexible organism can reduce the relative velocity between itself and the surrounding water, thereby reducing drag and lift. Motion of the body allows the organism to gain momentum, however, and this momentum can apply an inertial force when the organism's motion is slowed by the deformation of the body's supporting structures. Through a series of mathematical models we show that the inertial forces imposed on flexible plants and animals can be large enough to increase the overall force on the organism, more than offsetting the advantages of moving with the flow. A dimensionless index, the jerk number, is proposed as a tool for prdicting when inertial forces will be important, and the utility of this index is explored through an examination of the forces applied to kelps and mussels. The tendency for inertial loading to peak at certain frequencies raises the possibility that the structure of organisms can be tuned (either by evolution or physiological response) to avoid potentially damaging loads.

Page Thumbnails

  • Thumbnail: Page 
955
    955
  • Thumbnail: Page 
956
    956
  • Thumbnail: Page 
957
    957
  • Thumbnail: Page 
958
    958
  • Thumbnail: Page 
959
    959
  • Thumbnail: Page 
960
    960
  • Thumbnail: Page 
961
    961
  • Thumbnail: Page 
962
    962
  • Thumbnail: Page 
963
    963
  • Thumbnail: Page 
964
    964
  • Thumbnail: Page 
965
    965
  • Thumbnail: Page 
966
    966
  • Thumbnail: Page 
967
    967
  • Thumbnail: Page 
968
    968