Abstract Sand transport by wind in arid regions is a geomorphic process affected by the grain size distribution. Knowledge of the transport behavior of each size group in mixed sand transport is important for understanding the saltation dynamics in dune migration. This paper focuses on the characteristics of mass flux, mass concentration, horizontal velocity and transport rate of different particle size groups and the relation to their mass proportion in air. Experiments were carried out to analyze these relations in a wind tunnel by particle tracking velocimetry. The mass flux of different size particles usually decays exponentially with height for larger size groups and deviates from exponential decay for smaller size groups. The trend of mass concentration of different size groups with height is similar to the mass flux. The mean horizontal velocity of different size groups generally increases with increasing height and decreases with the increase of particle size at the same height. With increasing height, the ratio of mass flux of each size group to the total mass flux increases for the smaller size group but decreases for the larger size group, and the transition diameter of particles is about 0.14 mm for the 0.16 mm sand sample and about 0.21–0.27 mm for the 0.24 mm sand sample. For the smaller size group, the ratio of the mass-weighted average horizontal velocity of each size group to that of all particle sizes is >1.0, and the ratio of the transport rate of each size group to the total transport rate is usually larger than its mass proportion in air; this is the opposite for the larger size groups. The maximum deviation of mass flux proportion of each size group from its mass proportion in air is about ±15%, which is determined by the mass-weighted average horizontal velocity of each size group.

中文翻译：

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不同粒径颗粒在风吹输砂过程中的质量通量和输运速率试验研究

摘要 干旱地区风沙是受粒度分布影响的地貌过程。了解混合砂运移中每个大小组的运移行为对于了解沙丘迁移中的跃移动力学非常重要。本文重点研究了不同粒径组的质量通量、质量浓度、水平速度和输运速率的特征及其与空气中质量比例的关系。进行了实验以通过粒子跟踪测速法分析风洞中的这些关系。对于较大尺寸的组，不同尺寸粒子的质量通量通常随高度呈指数衰减，而对于较小尺寸的组则偏离指数衰减。不同尺寸组的质量浓度随高度的变化趋势与质量通量相似。不同粒径组的平均水平速度一般随着高度的增加而增加，在相同高度随着粒径的增加而降低。随着高度的增加，每个粒径组的质量通量与总质量通量的比值，较小粒径组增加，而较大粒径组减少，0.16 mm 砂样的颗粒过渡直径约为 0.14 mm，约0.21–0.27 mm 为 0.24 mm 沙样。对于较小的粒径组，各粒径组的质量加权平均水平速度与所有粒径的质量加权平均水平速度之比>1.0，且各粒径组的输运速率与总输运速率的比值通常大于其在空气中的质量比例；对于较大的组，情况正好相反。