Inter-particle collision effects on the entrained particle distribution in aeolian sand transport

摘要

Based on the Boltzmann transport equation, a theoretical model for the particle concentration distribution was developed in the aeolian sand transport to account for the inter-particle collision effects near the sand bed surface. In order to assess the inter-particle collision effects on sand transport characteristics near the sand bed surface, a set of experiments were performed in a large-scale wind tunnel with a dimension of 12,000 mm × 400 mm × 600 mm (L × W × H). Two types of sand samples were prepared by screening. The free-stream wind velocity in the wind tunnel was measured by HWA (Hot Wire Anemometer). The particle velocity, concentration, and Reynolds stress were obtained by PDPA (Phase Dopp-ler Particle Analyzer). Experimental results showed that particle concentration emerged a turning point at about 2 cm from the sand-bed surface. They agreed with the numerical simulation results very well. The collision rate of particles also emerged a turning point, and the location of the turning point was approximately consistent with that of the measured concentration and the Reynolds stress. Consequently, the inter-particle collision close to the sand-bed surface, which was the main factor that altered the characteristics of particle transport, could not be neglected.