Abstract: Sand particle rotation in windblown sand movement usually has obvious three-dimensional rotation characteristics. In this paper, a numerical model is developed to study the effect of Magnus force on the saltating trajectory under different particle rotation conditions in three-dimensional space. In the three-dimensional coordinates, the X, Y and Z axes denote the horizontal, vertical and transverse directions, respectively. The air flow is along the X direction and the sand particle starts to eject in the XY plane. The results show that when the particle ejects only with rotation around Z axis, with increase of ejected angular velocity, the saltation height and distance in XY plane decrease, the falling angle increases, but no motion occurs in Z direction. When the particle ejects only with rotation around X or Y axis, the ejected angular velocity has no obvious effect on the trajectory characteristics in XY plane, while the absolute values of deviation distance and deviation angle increase with the absolute value of ejected angular velocity. Hence, the ejected rotation condition of sand particle has an important effect on its saltation trajectory.

Key words: three-dimensional space, sand particle rotation, Magnus force, saltating trajectory