The fluctuating characteristics of streamwise wind speed and total saltation mass flux in the near-neutral atmospheric surface layer
The fluctuating characteristics of streamwise wind speed and total saltation mass flux in the near-neutral atmospheric surface layer
复制标题
近中性大气表层顺流风速和总跃移质量通量脉动特征
DOI：
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发表时间：
2023
期刊：
影响因子：
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通讯作者：
G. Han
中科院分区：
文献类型：
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作者：
Xiaobin Zhang;Bowen Zhang;Guowei Xin;G. Han
风成沙在大气近地层中的输运是一种典型的高雷诺数气固两相流，其输运过程具有很大的时空尺度波动。基于3个不同观测点的流向风速（u）和跃移总质量通量（q）的高频时间序列，分析了近中性ASL中u和q的波动特征。结果表明，在强稳定风沙流条件下，0.5 m高度处风速脉动的概率密度函数（PDF）服从标准正态分布，而在近中性ASL条件下，q值的概率密度函数（PDF）服从对数正态分布。对q和u的预乘谱的研究表明，随着超大尺度运动能量的增加，超大尺度运动对q的影响变得更加显著。此外，利用时空相关和线性相干谱分析了u和q之间的随机耦合。我们的研究结果表明，VLSM有一个显着的影响，在近中性ASL中的q的低频波动。
Aeolian sand transport in the atmospheric surface layer (ASL) is a typical kind of gas-solid two-phase flow at very high Reynolds number that fluctuates over a wide range of spatial and temporal scales. Based on the high-frequency time series of streamwise wind speed ( u) and total saltation mass flux ( q) measure at three different observation sites, the fluctuating characteristics of u and q in the near-neutral ASL have been analyzed. Our study suggests that the probability density function (PDF) of the normalized streamwise wind speed fluctuations at the height of approximately 0.5 m follows standard normal distribution, and the PDF of the q presents a lognormal distribution in the near-neutral ASL during strong and steady wind-blown sand. The investigations on the premultiplied spectral of q and u show that, as the energy of very large-scale motions (VLSMs) increases, the influence of the VLSMs on q become more significant. In addition, the stochastic couplings between u and q have been analyzed by using space-time correlations and linear coherence spectrum. Our results suggest that the VLSMs have a significant effect on the low-frequency fluctuations of q in the near-neutral ASL.