The influences of boundary layer thickness on the characteristics of saltation sand flow – A large eddy simulation study

IF 3.1 3区 地球科学 Q2 GEOGRAPHY, PHYSICAL Aeolian Research Pub Date : 2023-01-01 DOI:10.1016/j.aeolia.2023.100853
ShengJun Feng , Ping Wang
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引用次数: 2

Abstract

In this paper, Large Eddy Simulation (LES) of turbulence and Lagrangian model of sand particle motion are adopted to study the characteristics of wind-blown sand flow for different boundary layer thickness. The simulations are conducted within computational domain height (boundary layer thickness) of δ = 0.5 m, 1 m, 5 m and 12 m, respectively. It is found by comparing the computational results that the mass flux and sand transport rate increase with the increase of boundary layer thickness for the same frictional wind velocity, and the fluctuation of particle velocity and sand transport rate increase significantly too. The spatial scales of particle structure, defined by the correlation of sand particle concentration, significantly increase with δ, so does the time scale of statistical stability of sand transport rate. For two computational domains of δ = 1 m and 12 m, the statistical relative error of sand transport rate reduce to less than 5 % only when the average time goes higher than 45 δ/Ub, where Ub is the bulk fluid velocity. In the context of turbulence, it might take about 10 mins to obtain reliable sand statistics in the neutral atmospheric boundary layer whose boundary layer thickness is about 100–200 m.

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边界层厚度对跃变沙流特性的影响——大涡模拟研究
本文采用湍流大涡模拟(LES)和沙粒运动拉格朗日模型,研究了不同边界层厚度下的风沙流动特性。模拟分别在δ = 0.5 m、1 m、5 m和12 m的计算域高度(边界层厚度)范围内进行。对比计算结果发现,在相同的摩擦风速下,质量通量和输沙率随边界层厚度的增加而增加,颗粒速度和输沙率的波动也显著增加。以沙粒浓度相关性定义的颗粒结构空间尺度随δ显著增大,输沙率统计稳定性时间尺度随δ显著增大。对于δ = 1 m和12 m两个计算域,只有当平均时间大于45 δ/Ub (Ub为体流体速度)时,输沙率的统计相对误差才减小到5%以下。在湍流环境下,在边界层厚度约为100-200 m的中性大气边界层中,获得可靠的沙尘统计可能需要10分钟左右。
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来源期刊
Aeolian Research
Aeolian Research GEOGRAPHY, PHYSICAL-
CiteScore
7.10
自引率
6.10%
发文量
43
审稿时长
>12 weeks
期刊介绍: The scope of Aeolian Research includes the following topics: • Fundamental Aeolian processes, including sand and dust entrainment, transport and deposition of sediment • Modeling and field studies of Aeolian processes • Instrumentation/measurement in the field and lab • Practical applications including environmental impacts and erosion control • Aeolian landforms, geomorphology and paleoenvironments • Dust-atmosphere/cloud interactions.
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