A probability density function of liftoff velocities in mixed-size wind sand flux  

作　　者：ZHENG XiaoJing ZHU Wei XIE Li 

机构地区：[1]Key Laboratory of Mechanics on the Western Disaster and Environment,Ministry of Education,Lanzhou University,Lanzhou 730000,China

出　　处：《Science China(Physics,Mechanics & Astronomy)》2008年第8期976-985,共10页中国科学：物理学、力学、天文学（英文版）

基　　金：the Key Project of the National Natural Science Foundation of China (Grant No. 10532040)

摘　　要：With the discrete element method(DEM) ,employing the diameter distribution of natural sands sampled from the Tengger Desert,a mixed-size sand bed was produced and the particle-bed collision was simulated in the mixed-size wind sand movement. In the simulation,the shear wind velocity,particle diameter,incident velocity and incident angle of the impact sand particle were given the same values as the experimental results. After the particle-bed collision,we collected all the initial velocities of rising sand particles,including the liftoff angular velocities,liftoff linear velocities and their horizontal and vertical components. By the statistical analysis on the velocity sample for each velocity component,its probability density functions were obtained,and they are the functions of the shear wind velocity. The liftoff velocities and their horizontal and vertical components are distributed as an exponential density function,while the angular velocities are distributed as a normal density function.With the discrete element method (DEM), employing the diameter distribution of natural sands sampled from the Tengger Desert, a mixed-size sand bed was produced and the particle-bed collision was simulated in the mixed-size wind sand movement. In the simulation, the shear wind velocity, particle diameter, incident velocity and incident angle of the impact sand particle were given the same values as the experimental results. After the particle-bed collision, we collected all the initial velocities of rising sand particles, including the liftoff angular velocities, liftoff linear velocities and their horizontal and vertical components. By the statistical analysis on the velocity sample for each velocity component, its probability density functions were obtained, and they are the functions of the shear wind velocity. The liftoff velocities and their horizontal and vertical components are distributed as an exponential density function, while the angular velocities are distributed as a normal density function.

关 键 词：WIND SAND FLUX mixed-size particle diameter LIFTOFF velocity probability density function(PDF) discrete element method(DEM) 

分 类 号：O368[理学—流体力学]