Experimental study of particle concentration fluctuations in a turbulent steady flow

Abstract

Specific features of the physics of blown sand and PVC particles were investigated in wind-tunnel experiments. The fluctuations in particle concentration over time were derived from image processing of high-speed films (500 Hz). Spectral analysis of these time series showed a slowly decreasing slope within a frequency range that could be larger than the inertial sub-range of the free stream. A specific transport regime also appears in the lower part of the flow for frequencies less than 10 Hz. The role of turbulence in the generation of this regime is discussed using a simple theoretical model able to describe the aerodynamic behavior of a particle.

Measurements of the aeolian sand transport saturation length

“…We first report direct measurements of Lsat obtained from controlled experiments. They have been performed in the wind tunnel of the Cemagref in Grenoble (1m wide, 0.5m high, and 4.5m long), using sand grains of diameter d = 120±40µm from the Hostun quarry [Cierco et al 2008 ]. An initial 3cm thick sand bed is prepared and flattened with a moving bar.…”

Snow particle characteristics in the saltation layer

“…A detailed height-resolved analysis requires the application of other measurement techniques such as laser visualization and image-processing techniques, as previously employed for the study of aeolian transport of sand and PVC particles (e.g. Dong and others, 2003; Cierco and others, 2008; Creyssels and others, 2009). As a consequence, less knowledge of snow particle characteristics and dynamics (e.g.…”