Numerical Simulation And Wind Tunnel Experimental Analysis Of Windblown Sand Movement Over Slope Surface

Current theoretical studies and numerical simulations of windblown sand movement concentrate on ideal circumstances, such as steady wind velocity, flat sand surface, etc.. However, windblown sand movement environment is complex in the field, such as complex landform, turbulence structure of wind flow. Current theoretical and numerical models can't predict windblown sand saltating movement accurately. Actually, the gradient of the windward slope of the sand dune and the sand ripple, etc. Which is the basic form of the desert landscape, have great influence on the initiation and transportation of sand particles.In this paper, wind tunnel experiments are carried out and the wind velocity over the slope surface is measured by using the Phase Doppler Particle Analyzer technique and the characteristics of wind flow at the windward slope and at the leeward slope are analyzed. In addition, wind tunnel experiments were carried out and the dust emission rate over the slope surface was measured by using the Particle Image Velocity technique. Based on the wind tunnel experiment, we built up a theoretical model and simulated the windblown sand movement with considering the coupling of wind and sand particles. The finite volume method was used to solve the N-S equation, and staircase grids were used to approach the real surface configuration. The results show that the numerical results are fairly coincident with corresponding experimental results. Compared with flat bed surface, windblown sand movement characteristics are different over windward slope. Because of slope surface slope, along with the slope surface increased, wind velocity strengthened, sand emission rate and sand transport rate gradually increased; the effect of coupling is different at different position of windward slope.The results show that the numerical model cannot only simulate the wind flow characteristics of the slope surface effectively, but also displays the wind field structures of windward slope and leeward slope intuitively and comprehensively. Then windblown sand saltation movement, such as the profiles of sand transport rate and wind speed at different position over windward slop were discussed in details.