Advertisement

Threshold Speed and Grain Size

  • R. A. Bagnold

Abstract

WHEN the flow of air or of water over a flat bed of loose grains is gradually increased, there comes an instant when a few grains here and there begin to be dislodged and moved downstream by the force of the fluid upon them. At the instant of dislodgement any individual grain so moved is being turned about its leeward points of contact with the underlying grains, as indicated in Fig. 27. The force of the grain’s immersed weight, acting through the centre of gravity, is pulling the grain backwards and downwards; and this is just overbalanced by a drag force due to the fluid acting parallel to the general surface but at some rather indefinite height above the points of support.

Keywords

Wind Tunnel Critical Diameter Threshold Velocity Sand Surface Wind Strength 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Colebrook, C.F., and White, C.M. (1937). Proc. Roy. Soc. A., 161, p. 367.CrossRefGoogle Scholar
  2. Bagnold, R.A. (1937).Geogr. F., 89, p. 436.Google Scholar
  3. Hjulstrom, F. (1936). Bull. Geol. Inst. of Upsala, 25.Google Scholar
  4. Wentworth, C. (1932). Univ. Ia. Stud. Phys., 14.Google Scholar
  5. Barbour, G.B. (1936). Geogr. F., 86, p. 54.CrossRefGoogle Scholar

Copyright information

© Chapman and Hall Ltd 1973

Authors and Affiliations

  • R. A. Bagnold

There are no affiliations available

Personalised recommendations