风沙运动的DPM数值模拟

SIMULATION OF WINDBLOWN SAND MOVEMENT BY DISCRETE PARTICLE MODEL

采用离散颗粒模型对风沙气固两相流动进行了数值计算．在该模型中,采用体平均的Navier-Stokes方程来描述气相的运动,对离散颗粒采用拉格朗日方法模拟,求解颗粒运动方程．采用硬球模型描述颗粒问碰撞作用．计算结果表明,沙粒平均水平速度廓线在0．02 m以上高度可以表示为按对数函数或幂函数规律增加,在0．02 m以下则发生偏离;在大于0．02 m的高度,输沙通量随高度按指数规律衰减,而在地面附近由于颗粒蠕移的影响发生偏离,这与已有文献结果一致。本文的模拟有助于风沙运动规律的研究与掌握。

Numerical simulation of windblown sand gas-solid two-phase flow is performed with discrete particle model. In the model, the gas phase is described by the volume-averaged Navier- Stokes equations of two-phase flow. The particle motion is obtained by solving Newton＇s second law of motion. The hard sphere model is used to describe inter-particle collisions. The results show that, the variation of mean horizontal velocity of the sands with height can be expressed by a logarithmical function or a power function above 0.02 m and shows a deviation below 0.02 m. The sand mass flux decreases exponentially with height above 0.02 m, but there is a deviation from the exponential decay due to the creep grains in the near-bed region. The present simulation is helpful to reveal the mechanism in windblown sand movement.