Experimental Measurement of Wind Velocity Fluctuation and its Influences on Sand Particle Trajectory

The wind flow, the main driving force of sand movement, has already been known for its random fluctuation characteristics especially in the boundary layer. An experimental test for the wind velocity fluctuation is conducted for naturally mixed sands with a wind profiler in a field wind tunnel. On the basis of the experimental data, a fitting form of an empirical formula for the wind velocity fluctuation in the horizontal direction is obtained. After that, the influences of the wind velocity fluctuation are simulated on the particle trajectories, which demonstrate that the fluctuating velocity of the wind has greater influences on the trajectories of the particles with smaller diameter. The trajectory forms of the smaller sand particles, computed from the instantaneous velocity, might be in continuous saltation or even suspension besides smoothing parabola forms, which are obviously different from those computed only from the average velocity of the wind. For the particles with larger diameter, all the trajectories are almost the same in smoothing parabola forms under both fluctuating velocity and average velocity of the wind.