The Structure of Turbulent Shear Flow Around a Two-Dimensional Porous Fence Having a Bottom Gap

Kim, Hyoung-Bum; Lee, S.J.

doi:10.1006/jfls.2001.0423

Cited by 33 publications

(26 citation statements)

References 9 publications

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“…Taylor [92] found that drag coefficients decreased exponentially as the porosity of a two-dimensional barrier increased, but Grant and Nickling [91] demonstrated that a peak in drag coefficient occurred at an intermediate optical porosity (~20%) for three-dimensional trees. It has been shown that elements with a porosity less than 20% act to enhance wind speed recovery in their lee [68,[93][94][95], so elements with intermediate porosity strike a compromise between shear stress reduction and the downwind distance for which it is effective [96,97]. However, even porosity values of 50% can cause wake effects to extend to at least 50 h downwind of a windbreak [98].…”

Section: Trapping Of Windborne Sedimentmentioning

confidence: 99%

“…Gross [67] and Dupont et al [52] demonstrated using numerical models that wind flow accelerates over and around a single tree (Figure 2), and Leenders et al [46] and Mayaud et al [64] observed in the field that wind speed increases locally around the base of the trunk. A tree's elevated canopy produces a 'bottom gap' effect, whereby wind flowing near the top half of the tree moves over its crown [61] and streamline compression between the ground and underside of the crown results in wind speeding up [52,68].…”

Section: Introduction: the Drylands Contextmentioning

confidence: 99%

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Vegetation in Drylands: Effects on Wind Flow and Aeolian Sediment Transport

Mayaud

Webb

2017

Land

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Drylands are characterised by patchy vegetation, erodible surfaces and erosive aeolian processes. Empirical and modelling studies have shown that vegetation elements provide drag on the overlying airflow, thus affecting wind velocity profiles and altering erosive dynamics on desert surfaces. However, these dynamics are significantly complicated by a variety of factors, including turbulence, and vegetation porosity and pliability effects. This has resulted in some uncertainty about the effect of vegetation on sediment transport in drylands. Here, we review recent progress in our understanding of the effects of dryland vegetation on wind flow and aeolian sediment transport processes. In particular, wind transport models have played a key role in simplifying aeolian processes in partly vegetated landscapes, but a number of key uncertainties and challenges remain. We identify potential future avenues for research that would help to elucidate the roles of vegetation distribution, geometry and scale in shaping the entrainment, transport and redistribution of wind-blown material at multiple scales. Gaps in our collective knowledge must be addressed through a combination of rigorous field, wind tunnel and modelling experiments.

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Section: Trapping Of Windborne Sedimentmentioning

confidence: 99%

Section: Introduction: the Drylands Contextmentioning

confidence: 99%

Vegetation in Drylands: Effects on Wind Flow and Aeolian Sediment Transport

Mayaud

Webb

2017

Land

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“…The X coordinates were non-dimensionalized by each reattachment length. The centre-line of the shear layer can be depicted as Y 0.67 , which is the height of the Y coordinates when U is 0.67 U max (Kim and Lee [3]). The upper shear layer and the lower shear layer are Y 0.3 and Y 0.9 , respectively.…”

Section: Resultsmentioning

confidence: 99%

“…The fence flow can be manipulated for various purposes such as the reduction of drag, increasing/decreasing the mixing, and solving aero-optic problems (Kim and Lee [3], Andino et al [4]). …”

Section: Introductionmentioning

confidence: 99%

2D planar jet control for manipulating the separation bubble behind the vertical fence

et al. 2011

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The effect of a 2D planar jet was investigated to manipulate the separation bubble behind the vertical fence. The pulsating and continuous blowing jets were generated in front of or behind the fence. The experiments were carried out in a circulating water channel. The parameters used for controlling the jet included the distance between the slit nozzle and fence, the speed of the jet, and the frequency of the pulsating jet. The velocity fields were measured using phase-averaged DPIV method. From the results, the mechanism of reduction of the separation bubble and the quantitative effects of parameters to reduce the separation bubble behind the fence were found. A maximum reduction of 87% compared with the reattachment length of the uncontrolled fence flow was achieved using the front continuous jet. The controlled fence wakes have higher flow fluctuations and less sheltering effect than that of uncontrolled fence wake.

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“…In this paper, the research on how different barrier configurations (straight, curved and those with bottom gaps) affect the high velocity wind vortex produced by solid barriers is continued [8,9]. In this case, we have used the Post Method, which allows one to determine the particle emission from the pile surface by means of CFD modelling in Ansys CFX-10.0 software [3].…”

Section: Introductionmentioning

confidence: 99%

Dust emission reduction for open storage mineral piles by fences: CFD modelling

Torno

Rodríguez-Montañés

Allende

et al. 2010

WIT Transactions on Ecology and the Environment

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The significance of the dust emission study in open mineral storage piles is due to the great increase in bulk solids port terminals as a result of the increase in demand for different granular mineral.These piles are a significant source of pollutants into the atmosphere since they are affected by gusts of wind. The wind erodes the pile surface causing windblown particles to pollute the surrounding areas, cause sea water pollution in Port Systems and/or breathable air pollution in nearby areas.There are various preventive measures which minimize the erosion produced by the wind, such as total or partial covering, the use of water and chemical spraying which create a superficial crust and the colocation of natural or artificial fences (more widely used).In this research, the effect of different types of fence configurations, such as, straight, curved and with a bottom gap, for the particle emissions into the atmosphere has been analyzed by means of the Post Method which has been carried out by our Research Group incorporating Ansys CFX-10.0 software the US EPA (United States Environmental Protection Agency) emission formulae. The results obtained in this method have been proved and adjusted by measurement programmes that have been carried out in industrial installations.The best results correspond to the straight fence with a bottom gap located as much upstream as downstream from the pile.

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The Structure of Turbulent Shear Flow Around a Two-Dimensional Porous Fence Having a Bottom Gap

Cited by 33 publications

References 9 publications

Vegetation in Drylands: Effects on Wind Flow and Aeolian Sediment Transport

Vegetation in Drylands: Effects on Wind Flow and Aeolian Sediment Transport

2D planar jet control for manipulating the separation bubble behind the vertical fence

Dust emission reduction for open storage mineral piles by fences: CFD modelling

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