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	Height profile of the mean velocity of an aeolian saltating cloud: Wind tunnel measurements by Particle Image Velocimetry
	Yang, Ping; Dong, Zhibao; Qian, Guangqiang; Luo, Wanyin; Wang, Hongtao
刊名	GEOMORPHOLOGY
	2007-09-15
卷号	89期号:3-4页码:320-334
关键词	aeolian saltation mean velocity vertical variation measurement technique Particle Image Velocimetry (PIV)
ISSN号	0169-555X
DOI	10.1016/j.geomorph.2006.12.012
通讯作者	Dong, Zhibao(zbdong@lzb.ac.cn)
英文摘要	The velocity of saltating particles is an important parameter in studying the aeolian sand movement. We used Particle Image Velocimetry to measure the variation with height of the mean particle velocity of a saltating cloud over a loose sand surface in a wind tunnel. The results suggest that both the horizontal and vertical particle velocities fit the Gaussian distribution well, and that the mean particle velocity of a saltating cloud varies with wind velocity, particle size and the height above bed. The mean horizontal velocity is mainly the result of acceleration by the wind and increases with an increase in friction wind velocity but decreases with an increase in grain size because greater wind velocity causes more acceleration and finer particles are more easily accelerated at a given wind velocity. It also increases with an increase in height by a power function, in agreement with previous results obtained by other methods such as the high-speed multi-flash photographic method and Particle Dynamics Analyzer (PDA), reflecting, first, the increase in wind velocity with height through the boundary layer, and second, the longer trajectory-particle path length increases with height and affords a longer time for acceleration by the wind. An empirical model relating the mean horizontal particle velocity and height, friction wind velocity as well as particle size is developed. The ratio of the mean horizontal particle velocity to the clean wind velocity at the same height increases with height but decreases with grain size. The magnitude of mean vertical velocity is much less (one or two orders less) compared with the mean horizontal velocity. The average movement in the vertical direction of a saltating cloud is upward (the mean vertical velocity is positive). Although the upward velocity of a saltating particle should decrease with height due to gravity the mean vertical (upward) velocity (the average of both ascending and descending particles) generally shows a tendency to increase with height. It seems that at higher elevations the data are more and more dominated by the 'high-flyers'. The underlying mechanism for the mean vertical velocity distribution patterns needs to be clarified by further study. (c) 2007 Elsevier B.V. All rights reserved.
收录类别	SCI
WOS关键词	SAND ; COLLISIONS ; ENTRAINMENT ; GRAINS ; BED ; SURFACE ; SPEED ; MODEL
WOS研究方向	Physical Geography ; Geology
WOS类目	Geography, Physical ; Geosciences, Multidisciplinary
语种	英语
出版者	ELSEVIER SCIENCE BV
WOS记录号	WOS:000251895000007
内容类型	期刊论文
URI标识	http://www.corc.org.cn/handle/1471x/2555907
专题	寒区旱区环境与工程研究所
通讯作者	Dong, Zhibao
作者单位	Chinese Acad Sci, Cold & Arid Reg Environm & Engn Res Inst, Key Lab Desert & Desertific, Lanzhou 730000, Gansu, Peoples R China
推荐引用方式 GB/T 7714	Yang, Ping,Dong, Zhibao,Qian, Guangqiang,et al. Height profile of the mean velocity of an aeolian saltating cloud: Wind tunnel measurements by Particle Image Velocimetry[J]. GEOMORPHOLOGY,2007,89(3-4):320-334.
APA	Yang, Ping,Dong, Zhibao,Qian, Guangqiang,Luo, Wanyin,&Wang, Hongtao.(2007).Height profile of the mean velocity of an aeolian saltating cloud: Wind tunnel measurements by Particle Image Velocimetry.GEOMORPHOLOGY,89(3-4),320-334.
MLA	Yang, Ping,et al."Height profile of the mean velocity of an aeolian saltating cloud: Wind tunnel measurements by Particle Image Velocimetry".GEOMORPHOLOGY 89.3-4(2007):320-334.

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