The distribution of velocity and energy of saltating sand grains in a windtunnel

Sand transport by wind is a special case of two-phase flow of pas and solid s, with saltating grains accounting for about 75% of the transport rate. Th is form of flow is not only the main external agent moulding aeolian landfo rms but also the motive force responsible for transport, sorting and deposi tion of aeolian sediments. High-speed multiflash photography is an effectiv e method of studying the distribution of velocity and energy of saltating g rains within the boundary layer of wind tunnel. The experimental wind shear velocities were set at 0.63, 0.64, 0.74 and 0.81 ms(-1). The statistical s tudy of the results showed that there is a power function relation between mean velocity and height of saltating grains. As the height is divided into 0.5-cm intervals, the sand grain velocities at various levels are consiste nt with the Pearson VII distribution pattern. The variations in kinetic ene rgy and total energy of sand grains with height accord with the pulse peal, modified with power term (Pulsepow) law; the maximum values occur at heigh ts of 6 cm or so and tend to shift upward with increasing wind velocity. (C ) 2001 Elsevier Science B.V. All rights reserved.