关键词: 起动风速, 颗粒滚动, 碰撞, 起跳

Abstract: Soil particles release is a key influencing factor in soil wind erosion, but the study of release mechanism is lack and insufficient. In order to describe the vertical field which is engendered by temperature effect of earth surface, the basic soil particles release model of startingup，rolling motion and saltation of soil particles is established in this paper. At the same time, the numerical calculation results of the model are good agreement with predecessors’ experimental results, which indicates the model of this paper is appropriate. And the numerical simulation results of this paper show that with the particle diameter enlarging the threshold wind velocity weakens and then enlarges, and when the particle diameter is between 0.12 mm and 0.14 mm, the particle is the easier to start up. At the meantime, the higher the bed temperature is, the weaker the particles’ threshold wind velocity is. When the wind velocity is bigger than the threshold wind velocity, the particles begin to start up, they slide and at the time roll on the bed, the velocity of sliding and rolling gradually increases with the rolling distance increasing. When the rolling particles impact the other particle on the bed, they will liftoff, and the liftingoff velocity is between 0.3 m/s and 0.65 m/s (including vertical and horizontal liftingoff velocity); the liftingoff angle is between 30°and 35°; the liftingoff angular velocity is between 600 rev/s and 1 200 rev/s, which is good agreement with the experimental results of 100-1 000 rev/s and 300-900 rev/s. And based on it, the laws are given about releasing mechanism of soil particles, which is very important to improve the macromonitoring and forecasting in soil wind erosion.

Key words: threshold wind velocity, soil particle rolling, collision, liftoff