Abstract: The objective of this study is to identify and describe wind-blown sand motion near and around the highway in sandy desert areas. The Euler-Lagrange approach was used to describe a coupled gas-solid two-phase flow. The air flow was treated as a continuous phase flow by solving the time-averaged Navier-Stokes equations, while the discrete sand particle motion was calculated based on the mean continuous flow field. We conducted a series of numerical simulations with different parameters by using ANSYS k-ε model and Discrete Particle Model. The sand particle diameters range from 150 μm, to 200 μm, 250 μm, 300 μm, 350 μm, the friction velocity of air flow are from 0.20 m·s^-1, to 0.35 m·s^-1, 0.50 m·s^-1, 0.65 m·s^-1, 0.80 m·s^-1, the height of retaining wall are from 1.0 m, to 1.5 m, 2.0 m, 2.5 m, to 3.0 m, and a variety of retaining walls with different openings are considered as well. The sand particles passing the retaining wall were counted statistically, the typical wind velocity profiles were depicted in this paper. The numerical results show that the flow speeds up at the top of the retaining wall, which is positive to transport of particles, while the flow slows down in the front of the retaining wall and between the wall and the roadbed, which leads to the sand deposition near these zones. As the sand particle becomes larger, the ability of sand particles over the retaining wall becomes lower; with the friction velocity being larger, block effect of windbreak of sand decreases; and with increasing of the retaining wall height, the sand amount over the wall will reduce; meanwhile, the opening position and size of the retaining wall play an important role on the sand movement near the highway. It is concluded that the discrete particle model is useful to the calculation of sand saltation in air, and can provide some theoretical support for the control of windblown sand and for the safe running and operation of highway in sandy desert areas.

Key words: desert highway, wind-blown sand movement, retaining wall, discrete particle model, computational fluid dynamics