Fall velocities of saltating sand grains in air and their distribution laws

Cao, Hong; Zou, Xueyong; Zhang, Chunlai; Quan, Zhanjun

doi:10.1016/j.powtec.2008.12.001

Cited by 16 publications

(21 citation statements)

References 29 publications

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“…In previous experiments, the sand bed was always deemed as a flat surface [7,21,29], which did not consider the change of the sand bed during the development of windblown sand flux (it can generally arrive several millimeters). It was difficult to measure the actual ground surface using experimental apparatus at that time, so Werner [30] assumed that the fluctuation of the sand bed is not larger than one sand grain diameter.…”

Section: Discussionmentioning

confidence: 99%

“…One reason for this discrepancy is the lack of data on their incident velocities [21]. Actually, researchers also carried out some studies on the incident velocities and angles of saltating sand particles.…”

Section: Introductionmentioning

confidence: 99%

“…Actually, researchers also carried out some studies on the incident velocities and angles of saltating sand particles. However, a lot of research works focused on the incident angles [22,23] rather than velocities of the saltating sand particles, and there are less researches on the probability distribution of incident velocities of sand particles [19,21,22,24]. For example, Dong et al [22,24] suggested that with increasing lift-off angles the incident angles increase linearly, and the probability distribution of the incident velocities of saltating sand particles can be described by a Weibull distribution, and the resultant incident velocities of saltating sand particles followed a modified exponential distribution.…”

Section: Introductionmentioning

confidence: 99%

“…Kang et al [19] reported that the probability distributions of the lift-off and incident horizontal velocities of sand particles have a typical peak and are right-skewed (the observation height is 4 mm). Cheng et al [21] reported that the probability distributions of the incident angle and vertical velocities can be expressed as a Gamma function and the probability distributions of the horizontal and resultant incident velocities can be expressed as a Pearson IV function.…”

Section: Introductionmentioning

confidence: 99%

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Analysis of sand particles’ lift-off and incident velocities in wind-blown sand flux

Zheng

Duan

et al. 2013

Acta Mech Sin

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In the research of windblown sand movement, the lift-off and incident velocities of saltating sand particles play a significant role in bridging the spatial and temporal scales from single sand particle's motion to windblown sand flux. In this paper, we achieved wind tunnel measurements of the movement of sand particles near sand bed through improving the wind tunnel experimental scheme of paticle image velocimetry (PIV) and data processing method. And then the influence of observation height on the probability distributions of lift-off and incident velocities of sand particles was analyzed. The results demonstrate that the observation height has no obvious influence on the distribution pattern of the lift-off and incident velocities of sand particles, i.e., the probability distribution of horizontal and vertical velocities of lift-off and incident sand particles follow a Gaussian distribution and a negative exponential distribution, respectively. However, it influences the center of the Gaussian distribution, the decay constant and the amplitude of the negative exponential distribution.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Analysis of sand particles’ lift-off and incident velocities in wind-blown sand flux

Zheng

Duan

et al. 2013

Acta Mech Sin

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“…It has been verified that particle size distributions play an important role in the formation and evolution of sand ripples (Ling et al, 2003). The collision angle between sand grains and the bed increases with grain size (Jensen and Sørensen, 1986;Willetts and Rice, 1989;Rice et al, 1995;Fu et al, 2013) and decreases with wind velocity (Mitha et al, 1986;Cheng et al, 2009) as well as shadow zone length (Cooke and Warren, 1973). Furthermore, the latter increases with ripple wavelength (Schmerler et al, 2016), indicating that the wavelength of sand ripples decreases with collision angle (Hoyle and Woods, 1997).…”

Section: Introductionmentioning

confidence: 99%

Experimental study of aeolian sand ripples in a wind tunnel

Cao

Liu

et al. 2017

Earth Surf Processes Landf

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The topographic parameters and propagation velocity of aeolian sand ripples reflect complex erosion, transport, and deposition processes of sand on the land surface. In this study, three Nikon cameras located in the windward (0-1 m), middle (4.5-5.5 m), and downwind (9-10 m) zones of a 10 m long sand bed are used to continuously record changes in sand ripples. Based on the data extracted from these images, this study reaches the following conclusions. (1) The initial formation and full development times of sand ripples over a flatbed decrease with wind velocity. (2) The wavelengths of full development sand ripples are approximately twice the wavelengths of initially formed sand ripples. Both wavelengths increase linearly with friction velocity. During the developing stage of sand ripples, the wavelength increases linearly with time. (3) The propagation velocity of full development sand ripples is approximately 0.6 times that of the initially formed sand ripples. The propagation velocity of both initial and full development of sand ripples increase as power functions with respect to friction velocity. During the developing stage of sand ripples, the propagation velocity decreases with time following a power law. These results provide new information for understanding the formation and evolution of aeolian sand ripples and help improve numerical simulations.

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Aeolian creeping mass of different grain sizes over sand beds of varying length

et al. 2015

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Creep is an important mode of aeolian sand transport, but it has received little attention in previous studies due to experimental difficulties and insufficient theory. In this study, we conducted 116 groups of experiments with three repeats for each group in a wind tunnel to measure the creeping mass of four different mean grain sizes (152, 257, 321, and 382 μm) over six bed lengths (2.0, 3.5, 5.0, 6.5, 8.0, and 10.0 m) at six different friction velocities (0.23, 0.35, 0.41, 0.47, 0.55, and 0.61 m/s). We attempted to develop a comprehensive model of the aeolian creeping mass by analyzing the effect of wind velocity, the particle size, and the sand bed length based on the experimental data. The primary conclusions are as follows: (1) the complex relationship among the wind velocity, the grain size, the length of the bed, and the surface shape determines sand creep. There was no unified formula to express the effect of particle sizes and the sand bed length on aeolian creeping masses, and their effects appeared to depend on each other and wind velocity, whereas the creeping mass increases with increasing wind velocity for any particle size with any length of sand bed. (2) This paper presented a predicting model to determine the aeolian creeping mass, whose calculating results can match to experimental data with correlation coefficients (R 2 ) of 0.94 or higher. (3) The effect of grain size on creeping mass can be classified into three categories: the creeping mass increases with increasing grain size, the creeping mass initially decreases and subsequently increases with increasing grain size, and the creeping mass fluctuates with the grain size. (4) The effect of increasing bed length appears to depend on the grain size. For mean grain sizes of 152, 257, and 321 μm, creep initially increases with increasing bed length before decreasing above a certain value, while for a mean grain size of 382 μm, the creeping mass gradually increased with increasing bed length. The results help to elucidate aeolian creep and provide an intense foundation for advanced study.

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Fall velocities of saltating sand grains in air and their distribution laws

Cited by 16 publications

References 29 publications

Analysis of sand particles’ lift-off and incident velocities in wind-blown sand flux

Analysis of sand particles’ lift-off and incident velocities in wind-blown sand flux

Experimental study of aeolian sand ripples in a wind tunnel

Aeolian creeping mass of different grain sizes over sand beds of varying length

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