二维沙丘迎风坡沙粒跃移运动的数值模拟

为了研究沙丘迎风坡面上沙粒的跃移运动，本文根据风工程和空气动力学的最新理论，给出了沙丘迎风坡面上风场的空间分布规律，在此基础上对沙粒跃移运动进行了数值计算。由于沙丘周围流场情况较为复杂，各处的风速廓线也不同，故选取不同的坡面位置进行跃移计算，其中各处的起沙率由已有的实验结果或拟合公式给出。计算结果表明：从坡脚到坡顶，平均风速加速比和摩阻风速逐渐增加，到沙丘顶部达到最大值；同时沿坡面向上，各截面处单宽输沙率和距离当地地面相同高度处输沙浓度逐渐加强，这与已有文献报道的结果吻合良好。

Numerical Simulation of Saltation on the Windward Side of Sand Dunes

A new model is presented for calculating sand saltation on the windward side of two-dimensional dune. First, the wind profile is established by using the wind engineering and aerodynamics achievements, then the saltation of sand grains in a turbulent air flow is simulated by employing particle trajectory method. Since the wind field on the dune is quite complicated, and the wind profiles are different along the windward side of the dune, some typical positions are selected for numerical simulation. The surface ejection flux as initial condition in calculation is obtained by field measurement or empirical relationship with local friction velocity in literature. The numerical results show that the mean wind speed increases from the foot to the top of dune and reaches its maximum speed-up ratio at the dune top, the simulated sand transport rate and the mass flux profile are in good accordance with results reported in literature.