International audienc

A horizontal saltation layer of glass particles in air was investigated experimentally in a wind tunnel. Particle concentrations are measured by light scattering diffusion and image processing and all the statistical characteristics were evaluated and thus the probability density function. Our experimental results confirm that the mean concentration decreases exponentially with height, the mean Eulerian dispersion height H being a characteristic lengthscale and that the instantaneous concentration distribution c( x, t) is a random variable following quite well a lognormal distribution. To cite this article: X.

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.