坡面风沙运动的风洞实验及数值模拟

THE NUMERICAL SIMULATION AND WIND TUNNEL EXPERIMENT ON WINDBLOWN SAND MOVEMENT OVER THE SLOPE SURFACE

目前对近地层风沙流的理论与数值模拟研究都是在理想情况,如定常风速、平坦沙面等给定条件下对风沙流进行模拟研究,使得现有的风沙跃移运动理论与数值模型还远未能够达到准确预测野外实际情况下的风沙流运动的程度。该文进行了在坡面地表下风沙运动的风洞实验,在此基础上建立了坡面地表下的风场-沙粒相互耦合的风沙跃移运动模型,并对该风场-沙粒相互耦合的风沙跃移运动模型进行了求解。计算时采用有限体积法来求解Navier-Stokes方程,地表形态采用阶梯网格进行逼近,结果表明数值模拟结果与风洞实验结果吻合良好。该文还详细讨论了坡面地表下沙粒跃移运动特征,如坡面不同位置处输沙率沿高度的分布、风速沿高度分布等。

The existing theory studies and numerical simulations of windblown sand movement have been concentrated in idealized circumstances,such as steady wind velocity,flat bed surface,etc.As a result,current theoretical and numerical models can not predict windblown sand saltating movement accurately.In this paper,wind tunnel experiments were carried out and the dust emission rate over slope surface was measured by using the Particle Image Velocimetry technique.Based on the wind tunnel experiment results,we built up a theoretical model and simulated the windblown sand movement with consideration of 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 consistent with corresponding experimental results.Then windblow sand saltating movement,such as the profiles of sand transport rate and wind speed at different positions over slop surface were discussed in details.