Summary
Wind tunnel and field experiments are reported in which continuous, synchronous measurements of grain transport rates and near-bed velocity profiles were made at one second intervals to assess mass-flux response to velocity variations. Resulting grain flux and velocity series demonstrate the variability concealed by conventional time-averaged data. In steady tunnel winds, time-dependent mass transport rates are found to correlate better with fluctuations in mean velocity near the top of the saltation layer than with estimates of instantaneous shear stress. Quasi-periodic oscillation (20–30 seconds) of near-bed mass-flux and flow velocity in the lower regions of the inner boundary layer is evident in such airflows as the saltation system moves towards equilibrium with a developing bed form and confined boundary layer. This phenomenon may not occur in nature at these time-scales, however.
In systematically unsteady airflows, the time constant between flux rate and velocity near the top of the saltation layer is shown to be of order one second, tentatively confirming Anderson and Haff’s [2] calculations of saltation response time. Mass-flux also correlates well with large time-dependent variations in velocity in this region. Without grain replenishment, progressive surface re-sorting induces non-stationarity in grain flux under all observed flow regimes. Mass-flux and velocity histories measured on dunes show no correspondence. This difference is attributed to the stochastic nature of three-dimensional turbulence, the larger integral scales of atmospheric flows, measurement noise, and the effects of flow non-uniformity on satisfactory definition of shear velocity. Unsteady velocity profiles over a transverse dune are shown to be non-logarithmic above 20 cm but log-linear velocity segments of variable extent are found within the upper saltation layer.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Preview
Unable to display preview. Download preview PDF.
References
Anderson, R. S.: A theoretical model for aeolian impact ripples. Sedimentology 34, 943–956 (1987).
Anderson, R. S., Haff, P. K.: Simulation of eolian saltation. Science 241, 820–823 (1988).
Anderson, R. S., Sørensen, M., Willetts, B. B.: A review of recent progress in our understanding of aeolian sediment transport (this volume).
Bagnold, R. A.: The flow of cohesionless grains in fluids. Phil. Trans. Roy. Soc. A,249, 235–297 (1956).
Barndorff-Nielsen, O. E., Jensen, J. L., Nielsen, H. L., Rasmussen, K. R., Sørensen, M.: Wind tunnel tracer studies of grain progress. Proc. Int. Workshop on the Physics of Blown Sand, in Memoirs No. 8, Dept. Theor. Statist., Aarhus University, Denmark, 2, 243–251 (1985).
Belly, P. Y.: Sand movement by wind. Technical Memorandum No. 1, U.S. Army Coastal Eng. Res. Center, Washington D.C., 80 pp. (1964).
Busch, N. E., Panofsky, H. A.: Recent spectra of atmospheric turbulence. Quart. J. Roy. Meteorol. Soc. 94, 132–148 (1968).
Butterfield, G. R.: The instrumentation and measurement of wind erosion. Proc. Sixth New Zealand Geog. Conf. 1, 125–130 (1971).
Chiu, T. Y.: Sand transport by wind. University of Florida (Gainsville), Dept. Coastal and Oceanographic Engineering, Technical Report TR-040, (1972).
Folk, R. L., Ward, W. C.: Brazos River bar: a study of the significance of grain-size parameters. J. Sedim. Petrol. 27, 3–26 (1957).
Gerety, K. M.: Problems with determination of U * from wind-velocity profiles measured in experiments with saltation. In: Barndorff-Nielsen, O. E. et al. (eds.): Proc. Int. Workshop on the Physics of Blown Sand, in Memoirs No. 8, Dept. Theor. Statist., Aarhus University, Denmark, 2, 271–300 (1985).
Gillette, D. A., Stockton, P. H.: Mass momentum and kinetic energy fluxes of saltating particles. In: Aeolian geomorphology, (W. G. Nickling ed.), pp. 35–56, Boston: Allen & Unwin 1986.
Greeley, R., Iversen, J. D.: Wind as a geological process, p. 333. Cambridge: Cambridge University Press 1985.
Greeley, R., Leach, R. N., Williams, S. H., White, B. R., Pollack, J. B., Krinsley, D. H., Marshall, J. R.: Rate of wind abrasion on Mars. J. Geophys. Res. 87, 1009–1024 (1982).
Høgstup, J.: Velocity spectra in the unstable planetary boundary layer. J. Atmospheric Sci. 39, 2239–2248 (1982).
Horikawa, K., Shen, H. W.: Sand movement by wind action (on the characteristics of sand traps). Tech. Mem. No. 119, 119pp, US Army Beach Erosion Board, Wash. D.C., 1960.
Horikawa, K., Hotta, S., Kraus, N.: Literature review of sand transport by wind on a dry sand surface. Coastal Engineering 9, 503–526 (1986).
Howard, A. D., Walmsley, J. L.: Simulation model of isolated dune sculpture by wind. In: Barndorff-Nielsen, O. E. et. al. (eds.): Proc. Int. Workshop on the Physics of Blown Sand, in Memoirs No. 8, Dept. Theor. Statist, Aarhus University, Denmark, 2, 377–390 (1985).
Jensen, J. L., Rasmussen, K. R., Sørensen, M., Willetts, B. B.: The Hanstholm experiment 1982. Sand grain saltation on a beach. Dept. Theor. Statist., Aarhus University, Denmark, Research Report No. 125, 1984.
Jensen, J. L., Sørensen, M.: Estimation of some aeolian saltation transport parameters: a reanalysis of Williams’ data. Sedimentology 33, 547–558 (1986).
Jones, J. R., Willetts, B. B.: Errors in measuring uniform aeolian sand flow by means of an adjustable trap. Sedimentology 26, 463–468 (1979).
Kawamura, R.: Study on sand movement by wind. Reports of Physical Sciences research Institute of Tokyo University, 5, 95–112 (1951). [Translated from Japanese by National Aeronautic and Space Administration (NASA), Washington D. C. (1972)].
McLean, S. R., Smith, J. D.: A model for flow over two-dimensional bed forms. J. Hydraul. Eng. 112, 300–317 (1986).
Mulligan, K. R.: Velocity profiles measured on the windward slope of a transverse dune. Earth Surface Processes and Landforms 13, 573–582 (1988).
Nickling, W. G.: The initiation of particle movement by wind. Sedimentology 35, 499–511 (1988).
Owen, P. R.: Saltation of uniform grains in air. J. Fluid Mech. 20, 225–242 (1964).
Owen, P. R., Gillette, D. A.: Wind tunnel constraint on saltation. In: Barndoff-Nielsen, O. E. et. al. (eds.): Proc. Int. Workshop on the Physics of Blown Sand, in Memoirs No. 8, Dept. Theor. Statist., Aarhus University, Denmark, 2, 253–269 (1985).
Phillips, C. J., Willetts, B. B.: A review of selected literature on sand stabilization. Coastal Engineering 2, 133–147 (1978).
Rasmussen, K. R., Mikkelsen, H. E.: Development of a boundary layer wind tunnel for aeolian studies. Geoskrift No. 27, Geologisk Institut, Aarhus University, Denmark, (1988).
Rasmussen, K. R., Mikkelsen, H. E.: On the efficiency of sand traps and the transport rate profile. Sedimentology 38, in press (1991).
Rasmussen, K. R., Sørensen, M., Willetts, B. B.: Measurement of saltation and wind strength on beaches. In: Barndorff-Nielsen, O. E. et. al. (eds.): Proc. Int. Workshop on the Physics of Blown Sand, in Memoirs No. 8, Dept. Theor. Statist., Aarhus University, Denmark, 2, 301–325 (1985).
Raes, G.: Een windtunnelstudie over het effect van de tÿd op de granulometrie en de deflatiegevaeligheid by erosie van een ‘loessig’ materiaal. M. Sc. Thesis, K. U. Leuven, 116pp. 1988.
Sarre, R. D.: Aeolian sand transport. Progr. Phys. Geog. 11, 157–182 (1987).
Sarre, R. D.: Evaluation of aeolian sand transport equations using intertidal zone measurements, Saunton Sands, England. Sedimentology 35, 671–679 (1988).
Task Committee on Preparation of Sedimentation Manual: Sediment transportation mechanics: wind erosion and transportation. J. Hydraul. Div. Am. Soc. Civ. Engrs. 91 (HY2), 267–287 (1965).
Ungar, J. E., Haff, P. K.: Steady state saltation in air. Sedimentology 34, 289–299 (1987).
White, B. R., Mounla, H.: An experimental study of Froude number effect on wind-tunnel saltation (this volume).
Williams, G.: Some aspects of the eolian saltation load. Sedimentology 3, 257–287 (1964).
Williams, J. J., Butterfield, G. R., Clark, D.: Aerodynamic entrainment threshold: effects of boundary layer flow conditions. Sedimentology 38, in press (1991).
Williams, J. J., Butterfield, G. R., Clark, D.: Rates of aerodynamic entrainment in a developing boundary layer. Sedimentology 37, 1039–1048, (1990).
Zingg, A. W.: Wind tunnel studies of the movement of sedimentary material. Proc. Fifth Hydraulics Conf., Iowa University Studies in Engineering Bulletin 34, 111–135 (1953).
Author information
Authors and Affiliations
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 1991 Springer-Verlag Wien
About this paper
Cite this paper
Butterfield, G.R. (1991). Grain transport rates in steady and unsteady turbulent airflows. In: Barndorff-Nielsen, O.E., Willetts, B.B. (eds) Aeolian Grain Transport 1. Acta Mechanica Supplementum, vol 1. Springer, Vienna. https://doi.org/10.1007/978-3-7091-6706-9_6
Download citation
DOI: https://doi.org/10.1007/978-3-7091-6706-9_6
Publisher Name: Springer, Vienna
Print ISBN: 978-3-211-82269-2
Online ISBN: 978-3-7091-6706-9
eBook Packages: Springer Book Archive