Air flow and sand transport over sand-dunes

  • W. S. Weng
  • J. C. R. Hunt
  • D. J. Carruthers
  • A. Warren
  • G. F. S. Wiggs
  • I. Livingstone
  • I. Castro
Part of the Acta Mechanica Supplementum book series (ACTA MECH.SUPP., volume 2)


Developments in the modelling of turbulent wind over hills and sand dunes of different shapes by Hunt et al. [1], Carruthers et al. [2] are briefly described, and compared with earlier studies of Jackson and Hunt [3] and Walmsley et al. [4]. A new model (FLOWSTAR) is described; it has a more accurate description of airflow close to the surface, which is not in general logarithmic at typical measurement heights. Comparisons are made between the new model and the results of non-linear models using higher-order turbulence schemes, especially for surface shear stress.

The widely predicted and observed drop in velocity and shear stress at the base of a dune is confirmed by FLOWSTAR. It is clear that common models for the saltation flux based only on µ* are not appropriate at the toe of the dune where they predict a piling-up of sand.

Comparisons of the wind speed are made between the model and different sets of measurements over a dune, by Howard and Walmsley [5], and by our group in recent field measurements over a dune in Oman, and in a new wind-tunnel study of Howard’s dune. It is found that the FLOWSTAR calculations agree well with these sets of measurements upwind of the brink. Since the profile is not logarithmic over the dune at the measurement heights, estimates of µ* from wind measurements over dunes are likely to be less accurate than the FLOWSTAR computation of µ*. The saltation flux was measured over the Oman dune and increases in proportion to computed value of µ* 3 over the dune. This supports the use of the Lettau and Lettau version of Bagnold’s flux formula for modelling sand transport over the most of the upwind slopes of sand dunes.


Sand Dune Normalise Wind Speed Sand Transport Saltation Flux Surface Shear Stress 


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Copyright information

© Springer-Verlag Wien 1991

Authors and Affiliations

  • W. S. Weng
    • 1
  • J. C. R. Hunt
    • 2
  • D. J. Carruthers
    • 1
  • A. Warren
    • 3
  • G. F. S. Wiggs
    • 3
  • I. Livingstone
    • 4
  • I. Castro
    • 5
  1. 1.CERC LfdCambridgeUK
  2. 2.Department of Applied Mathematics and Theoretical PhysicsUniversity of CambridgeCambridgeUK
  3. 3.Department of GeographyUniversity College LondonLondonUK
  4. 4.Department of GeographyCoventry PolytechnicCoventryUK
  5. 5.Department of Mechanical EngineeringUniversity of SurreyGuildfordUK

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