Initiation of motion of quartz sand grains

  • B. B. Willetts
  • I. K. McEwan
  • M. A. Rice
Part of the Acta Mechanica Supplementum book series (ACTA MECH.SUPP., volume 1)


Direct observation at a limited range of wind speeds of grain behaviour near the upwind edge of a sand deposit (by means of high-speed film) shows that disturbed grains usually, but not always, roll before taking off into reptation or saltation. Time-averaged description of the population of initial motions is deficient because of the importance of pronounced flurries of grain activity which occur at intervals. The flurries are clearly associated with flow features in the clean air wind because they occur too close to the leading edge to be impact generated.

An adapted saltation model is used to explore the development of activity downwind which results from a sequence of first dislodgements (into rolling or take-off) recorded on film. The portrayal of the development of a saltation layer is plausible and can be checked by means of flux profile measurements. However, it emphasises the need for more information about turbulence in the grain laden layer.


Wind Speed Wind Tunnel Mass Flux Quartz Sand Sand Deposit 
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.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. [1]
    Bagnold, R. A.: The physics of blown sand and desert dunes. London: Methuen 1941.Google Scholar
  2. [2]
    Mitha, S., Tran, M. Q., Werner, B. T., Haff, P. K.: The grain bed impact process in aeolian saltation. Acta Mech. 63, 267–278 (1986).CrossRefGoogle Scholar
  3. [3]
    Rumpel, D. A.: Successive aeolian saltation: studies of idealised conditions. Sedimentology 32, 267–280 (1985).CrossRefGoogle Scholar
  4. [4]
    Willetts, B. B., Rice, M. A.: Collision in aeolian saltation. Acta Mech. 63, 255–265 (1986).CrossRefGoogle Scholar
  5. [5]
    Anderson, R. S., Haff, P. K.: Simulation of aeolian saltation. Science 241, 761–776 (1988).Google Scholar
  6. [6]
    Werner, B. T.: A steady state model of windblown sand transport. J. Geol. 98, 1–17 (1990).CrossRefGoogle Scholar
  7. [7]
    Rice, M. A.: Grain shape effects on aeolian sediment transport (this volume).Google Scholar
  8. [8]
    Willetts, B. B.: Transport by wind of granular materials of different grain shapes and densities. Sedimentology 30, 669–679 (1983).CrossRefGoogle Scholar
  9. [9]
    McEwan, I. K., Willetts, B. B.: Numerical model of the saltation cloud (this volume).Google Scholar
  10. [10]
    Williams, J. J.: Aeolian entrainment thesholds in a developing boundary layer. Ph. D. Thesis, University of London (1986).Google Scholar

Copyright information

© Springer-Verlag Wien 1991

Authors and Affiliations

  • B. B. Willetts
    • 1
  • I. K. McEwan
    • 1
  • M. A. Rice
    • 1
  1. 1.Department of EngineeringKings CollegeAberdeenUK

Personalised recommendations