Defining the threshold wind velocity for moistened sediments
Defining the threshold wind velocity for moistened sediments
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DOI：
10.1029/2006jb004476
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发表时间：
2007-08
影响因子：
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通讯作者：
Z. Dong;Qing-song Mu;Xiaopiu Liu
中科院分区：
文献类型：
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作者：
Z. Dong;Qing-song Mu;Xiaopiu Liu
[1]表层沉积物中的水分是决定颗粒在风作用下开始运动的最重要因素之一，因此也是决定风成输运速率的最重要因素。本文采用力矩平衡法，考虑了水分在颗粒间产生的粘聚力，建立了一个物理基础更坚实的起动剪切流速方程。该方程将临界剪切速度直接与含水量联系起来，并包含三个需要通过实验确定的简单系数。潮湿沉积物的阈值方程基本上遵循Bagnold的松散，干燥的沉积物的阈值方程，但与比例系数，占水分的影响。利用已有的湿泥沙起动风速风洞试验资料确定了起动方程中的系数，证明了新方程能较好地描述湿泥沙起动风速。将新方程预测的临界剪切速度与Belly和Hotta等人的结果进行比较。的经验公式表明，预测结果差异很大。这些差异可归因于起动流速和含水量的定义、沉积物样品的物理和化学性质以及实验方法的不同。为充分了解泥沙含水率对起动风速的影响，还需要进一步的理论和试验研究。我们还建议，方法的改进本身也是未来研究的一个主题。
[1] The moisture of surface sediments is one of the most significant factors governing the initiation of particle movement by the wind and hence the aeolian transport rate. This paper develops an equation for the threshold shear velocity of moistened sediments based more soundly on physics by means of the moment balance method, taking account of the interparticle cohesive forces produced by moisture. The equation relates threshold shear velocity directly to moisture content and contains three simple coefficients that need be determined from experiments. The threshold equation for moistened sediments basically follows Bagnold's threshold equation for loose, dry sediments but with a proportionality coefficient that accounts for the effect of moisture. Previously published data on the threshold shear velocities of moistened sediments from wind tunnel tests are used to determine the coefficients contained in the threshold equation, and it proves that the new equation describes the threshold velocities of moistened sediments reasonably well. Comparing the threshold shear velocity predicted using the new equation with the results of Belly's and Hotta et al.'s empirical equations reveals that the predicted results differed greatly. These differences can be attributed to differences in the definition of threshold velocity and moisture content in the physical and chemical properties of the sediment samples and in the experimental methods. Further theoretical and experimental investigation is required to fully understand the effects of sediment moisture content on threshold wind velocity. We also suggest that methodological improvement itself is also a topic of future research.