Numerical modelling of saltation in the atmospheric surface layer
Numerical modelling of saltation in the atmospheric surface layer
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DOI：
10.1023/a:1001816013475
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发表时间：
1999-05-01
影响因子：
4.3
通讯作者：
Li, A
中科院分区：
文献类型：
--
作者：
Shao, YP;Li, A
开发了一个数值模型来研究中性大气表层中沙粒的跳跃运动（跳跃）。跃动被认为是一个自限过程，由四个部分的相互作用控制：空气动力夹带、粒子运动、飞溅夹带和风修正。该模型包括大气表层流动的大涡模拟模型、粒子轨迹的拉格朗日模型以及气动夹带和飞溅夹带的统计描述。数值模拟的重点是实验研究中尚未充分理解的跳动方面，包括飞溅的作用、风和动量通量剖面的演变以及有效粗糙度长度 z(0)s。结果表明，为了使飞溅有效，表面摩擦速度必须超过给定颗粒尺寸的临界值。将数值估计的 z(0s) 与 Raupach 的分析模型和 Gillette 等人的实验数据进行了比较。该模型还用于计算流向沙流，数值结果与现有风洞测量结果一致。
A numerical model is developed to study the hopping motion of sand grains (saltation) in neutral atmospheric surface layers. Saltation is considered as a self-limiting process governed by the interaction of four components: aerodynamic entrainment, particle motion, splash entrainment and wind modification. The model comprises a large eddy simulation model for atmospheric surface-layer flows, a Lagrangian model for particle trajectories and a statistical description for aerodynamic entrainment and splash entrainment. The numerical simulation is focused on the aspects of saltation that are not well understood from experimental studies, including the role of splash, the evolution of wind and momentum flux profiles, and the effective roughness length, z(0)s. It is shown that for splash to be effective, the surface friction velocity must exceed a critical value for a given particle size. The numerically estimated z(0s) is compared with the analytical model of Raupach and the experimental data of Gillette et al. The model is also used to calculate the streamwise sand drift and the numerical results found to be in agreement with the existing wind-tunnel measurements.