Analysis of force acting on sand particles by using a high-speed digital camera

Wind tunnel experiments were carried out to investigate the saltation of sand particles in the atmospheric boundary layer. A high-speed digital camera was employed to record the saltating sand particles' trajectories. The overlapping particle tracking velocimetry algorithm was introduced to process the consecutive images. By the advantages of high-speed digital camera, motion parameters of single sand particle can be obtained much easier and with a high temporal resolution than that of conventional photography. Velocities and accelerations of sand particles along the whole trajectory were calculated. Furthermore, proportions of forces acting on the saltating sand particles were analyzed to learn their relative significance. The results showed that, besides gravity, the aerodynamic drag was the main force that affected the motion of sand particles.