Quantification of Particle Velocities and Energy Regime in an Aeolian Abrasion Chamber

Abstract

Particle breakdown and fine sediment production by wind abrasion is of long-standing interest in aeolian science as it contributes to erosion and dust production on Earth and other planetary bodies. The process of aeolian abrasion is largely measured in laboratories to enable standardization of parameters and allow simulation of saltation over long time periods. To be effective, abrasion simulators must reproduce particle interactions similar to those observed in the natural environment. This paper quantifies the particle velocities, pathways and energy regime within a widely used “test-tube” abrasion chamber. For 17 different sand samples, the instantaneous two-dimensional vertical and horizontal velocity components of particles moving within the chamber were sampled using a laser Doppler anemometer. Similar to a natural saltation cloud, the movement of particles in the chamber is stochastic and there is a positive relationship between the air inflow rate and the depth of the saltation layer. For air inflow of 14.9 m s⁻¹, particle velocities range from 0.01 to 3.2 m s⁻¹ with median velocity for all particles in the chamber varying from 0.29 to 0.56 m s⁻¹, and total energy ranging from 0.54 to 1.38 J kg⁻¹. These values are similar to those determined for natural saltation clouds. For a constant air inflow rate, the mean total particle velocity increases with particle size. Air inflow rate has a significant effect on mean total particle velocity but between 10 and 100 g the quantity of sample tested is not important. The contribution of this type of experiment to understanding aeolian abrasion processes is evaluated.