Dispersion Of Solid Saltating Particles In A Turbulent Boundary Layer
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H. T. Wang, Z. B. Dong, X. H. Zhang & M. Ayrault
A horizontal saltation layer of glass particles in air is investigated experimentally both on a flat bed and over a two-dimensional ridge. Particle concentrations are measured by Mie scattering diffusion. All the statistical moments of the particle concentration are determined such as mean concentration, rms concentration fluctuations, skewness and flatness coefficients. Measurements of particle concentrations were made at the top of the ridge and in the cavity region. It is confirmed that over a flat bed the mean concentration decreases exponentially with height, the mean dispersion height H being of great meaning. It is shown that the concentration distribution follows quite well a lognormal distribution. At the top of the ridge, the saltation layer is decreased and the concentration increased. Keywords: particles, saltation, dispersion, turbulent boundary layer. 1 Introduction Wind erosion is a major cause of soil degradation in arid and semi-arid areas and deserts. It is therefore of great importance to analyze both experimentally and theoretically the motion of wind-blown particles in order to develop effective wind erosion modeling system for controlling the wind erosion of small particles. Saltation is the primary wind erosion mechanism. Initially aerodynamically lifted off by the wind in short hops and although accelerated by the wind, particles will return to the bed and will impact the ground, rebounding and/or
particles, saltation, dispersion, turbulent boundary layer.