Mechanics of Wind-blown Sand Movements

Zheng, Xiaojing

doi:10.1007/978-3-540-88254-1

Cited by 128 publications

(77 citation statements)

References 143 publications

(245 reference statements)

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“…A number of researchers have studied the dynamics of sand dunes, and several comprehensive reviews, e.g., Shao (2001) and Zheng (2009), provide some highlights of the progress in understanding this subject. For example, Bagnold (1954) classified three types of sand movement in atmosphere: saltation, suspension, and surface creep.…”

Section: Introductionmentioning

confidence: 99%

Visualization and laser measurements on the flow field and sand movement on sand dunes with porous fences

et al. 2011

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The installation of windbreak sand fences around sand dunes is one of the most promising methods to suppress windblown sand movement. In the study reported in this paper, we investigated the influence and validity of a small fence mounted on a model sand dune, in order to understand the fence's suppression mechanism on the sand movement. The flow field around the dune and the process of sand-dune erosion were measured using LDV, PIV, and laser-sheet visualization techniques. A non-porous fence was found to suppress sand movements in its upstream area, but to enhance erosion downstream of the fence. This intensive erosion was caused by separated shear flow from the leading edge of the fence. In this study, four levels of porosity rate of the fence were tested. The fence-porosity dependences of the turbulent flow field and the erosion were discussed. The shapes of eroded sand dunes were found to depend on the porosity rate. The relationship between the sand-dune erosion and the flow field around the dune was illustrated with schematic diagrams. We concluded that the most desirable fence porosity should be 30% in order to avoid dune erosion if installed at a middle height on the stoss surface of a dune. This porosity provides a mean velocity reduction with avoiding a separated flow, although the flow bleeding through the porous fence is accompanied by grid turbulence and induces serious erosion in a narrow space behind the fence. Furthermore, we confirmed that the empirical correlation of the critical friction velocity can be applied to sand movements influenced by a fence.

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Section: Introductionmentioning

confidence: 99%

Visualization and laser measurements on the flow field and sand movement on sand dunes with porous fences

et al. 2011

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“…Although CA modelling is effective at creating realistic dune forms under a range of conditions such as wind direction (Zhang et al, 2012) and vegetation (Nield and Baas, 2008), the simple assumptions determining the models outcome cannot yet be used to predict morphological change in reality (Zheng, 2009). Furthermore the two-dimensional nature of flow modelling conducted in CA modelling does not permit users to adequately investigate lateral patterns of deposition or erosion that may occur.…”

Section: Dune Morphological Modellingmentioning

confidence: 99%

Aeolian dynamics of beach scraped ridge and dyke structures

Smyth

Hesp

2015

Coastal Engineering

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Where urban areas are situated close to a beach, sand dunes act as protection from flooding and erosion. When a dune has been removed or damaged by erosion, dune, ridge or dyke re-building using heavy machinery, a process known as beach scraping, is a common method of restoration. Following construction, natural accretion of sediment on the backshore is preferable as it facilitates sustained natural dune building, growth of vegetation, habitat creation and reduces the need for further beach scraping.This study investigates the near surface flow and transport potential for three artificial structure designs: a single ridge, a double ridge and a dyke. The three shapes contained an identical volume of sand and were preceded by 50 m of beach at an angle of 3°. A computational fluid dynamic model (CFD) was created for each scenario to calculate wind flow and shear velocity from 4 different wind directions at 22.5° intervals from 0° (onshore) to 67.5°. From this data sediment flux was predicted along a two dimensional transect for each of the scenarios.For all structures, shear velocity on the beach and stoss slope decreased as incident wind direction became more oblique, conversely shear velocity in the lee of the crest increased. A reduction in shear velocity at the foot of each structure also occurred and appears related to stoss slope, with the reduction greatest reduction at the toe of the dyke structure (stoss slope 34°) and the least before the single ridge (stoss slope 17°).Specifically the results suggest that the double ridge structure is the most resilient to aeolian erosion. Shear velocity reduction on the back beach is comparable to the dyke and sediment flux from the stoss slope of the double ridge structure may become trapped in the swale between the two ridges encouraging sediment deposition, thus reducing sediment transport beyond the dunes and backshore. Although the dyke structure underwent the greatest reduction in shear velocity on the back beach it experienced substantial sediment flux at the crest and along the top of the structure, making it susceptible to erosion during a strong wind event. The highest sediment transport rate was calculated at the crest of the single ridge, and the single ridge structure also created the smallest reduction of shear velocity on the back beach, thus making it less desirable than the double ridge.

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“…Specifically, the research for aeolian sediment transport proves to be of vital importance in many coastal and desert areas, even in the evolution of landforms on Mar [1][2][3]. Bagnold (1941) proposed the transport rate formula based on the loss of momentum and this formed the foundation for the numerical simulation of aeolian transport [4].…”

Section: Introductionmentioning

confidence: 99%

“…However, there are still some simplification and assumptions in these models and so far none of these models have been shown to accurately widely applicable in all situations, there is an urgent need to improve the model quality from the most basic physical and mechanical mechanism. In the meantime, most of these excellent researches on aeolian sediment transport are conducted based on three-dimensional mathematical models [3,8,14,15], which can capture the characteristics of sediment transport processes very well, but are also very costly and time consuming when applied to large scale cases, and there is still a great demand from practical engineering application and environmental problems that a model can be effectively used for large scale numerical simulations. To this end, in the present study, the integral average method which is widely applied to wide shallow river or estuary and large-scale reservoir numerical simulation is introduced to aeolian sediment transport modeling.…”

Section: Introductionmentioning

confidence: 99%

Unified Integral Model for Fluvial and Aeolian Sediment Transport

Li¹,

Wang²,

Zhou³

et al. 2017

dteees

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Abstract. The commonly used three-dimensional mathematical model in aeolian sediment transport modeling could inevitably turn out to be very costly and time consuming when applied to large scale simulation. In this study, a depth-averaged numerical model which is widely applied to fluvial sediment transport numerical simulation is introduced to aeolian sediment transport modeling. Model validity has been assessed using experimental data of aeolian saltation cases, and the results have shown that the major features of aeolian sediment transport can be well captured by the proposed model.

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Mechanics of Wind-blown Sand Movements

Cited by 128 publications

References 143 publications

Visualization and laser measurements on the flow field and sand movement on sand dunes with porous fences

Visualization and laser measurements on the flow field and sand movement on sand dunes with porous fences

Aeolian dynamics of beach scraped ridge and dyke structures

Unified Integral Model for Fluvial and Aeolian Sediment Transport

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