LES-DEM study of 3-D motion of sand particles nearing bed in Aeolian sand transport

The numerical code base on coupling of large-eddy simulation (LES) and discrete element method (DEM) is developed. Three dimensional transport of gas-solid two phase aeolian sand is simulated with the code. Velocities and angles of incident and lift-off sand particles near the surface of sand bed are analyzed statistically. The results show that the code is able to simulate the features of motion of sand particles in aeolian sand flow. The lognormal function can be used to express the distribution of incident and lift-off velocities of sand particle. The value of distribution functions in a more focused with the increase of wind speed. Angle of incident and lift-off concentrate in 10 and 15 degree separately. This indicate that the momentum of sand particles tend to transfer to the vertical direction. Spanwise velocities of sand are more significant with the increase of wind speed.