Flow and dispersion of pollutants within two-dimensional valleys

Snyder, William H.; Khurshudyan, L. H.; Nekrasov, Igor V.; Lawson, Robert E.; Thompson, Roger S.

doi:10.1016/0960-1686(91)90245-3

Cited by 23 publications

(14 citation statements)

References 17 publications

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“…As implied above, the experiments of Snyder et al (1991), initially reported by Khurshudyan et al (1990) and with data subsequently archived in smoothed form by Busuoli et al (1993), is really the only previous relevant and well-controlled wind tunnel study. It was quite extensive and provides cleaner idealisations than the Sierputowski et al (1995) experiment since the valleys were genuinely sunk beneath the surface level of the upstream (and downstream) boundary layer.…”

Section: Background and Motivationmentioning

confidence: 99%

“…Subsequently, the present field situation is outlined and then, in Section 3, we provide details of the model valley, the wind tunnel set up and the techniques for the present experiments, along with the characteristics of the simulated atmospheric boundary layer. Section 4 presents the major results and includes comparisons with the Snyder et al (1991) data where appropriate. Final discussion and conclusions are given in Section 5.…”

Section: Background and Motivationmentioning

confidence: 99%

“…Furthermore, the valley shape was purposely chosen as an idealisation of the field case and our studies include a case when the valley axis is not normal to the approach flow. Nonetheless, it is appropriate here to summarise the findings of Snyder et al (1991) as far as the flows themselves are concerned, and this is done in the following section. Subsequently, the present field situation is outlined and then, in Section 3, we provide details of the model valley, the wind tunnel set up and the techniques for the present experiments, along with the characteristics of the simulated atmospheric boundary layer.…”

Section: Background and Motivationmentioning

confidence: 99%

“…In contrast to the situation for hills, little is known about the effects of the valley on mean wind and turbulence structure both upwind and downwind, as well as within the valley itself, and there has never been an adequate field study to identify the effects of isolated valleys in flat, plateau terrain on boundary layer winds. Sierputowski et al (1995) and Snyder et al (1991) have reported practically the only relevant wind tunnel studies. The former is complicated by the fact that the valley was formed between two hills, so the flow field within the valley was undoubtedly affected by that over the upstream hill.…”

Section: Background and Motivationmentioning

confidence: 99%

“…Final discussion and conclusions are given in Section 5. Snyder et al (1991) used three smoothly-shaped valleys of fixed depth H -some 12% of the upstream boundary layer height, δ, or about 730z o , where z o is the roughness length of the undisturbed, upstream boundary layer. Valley widths in the axial (wind) direction were 6, 10 and 16H and the respective maximum slopes were 26 o , 16 o and 10 o .…”

Section: Background and Motivationmentioning

confidence: 99%

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Measurements of Flows Over Isolated Valleys

Garvey

Castro

Wiggs

et al. 2005

Boundary-Layer Meteorol

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Abstract. Wind tunnel measurements of the flow over an isolated valley both normal and at an angle (45 o ) to a simulated neutrally stable atmospheric boundary layer are presented. Attention is concentrated on the nature of the near-surface flow upwind and downwind of the valley and the character of the flow within the valley itself. The work formed part of a wider study which included detailed field measurements around an African desert valley and some limited comparisons with that work are included. A scale of about 1:1000 was used for the laboratory work, in which an appropriate combination of hot wire and particle image velocimetry was employed. For a valley normal to the upwind flow, it is shown that the upstream influence of the valley extends to a distance of at least one half of the axial valley width upstream of the leading edge, whereas differences in mean flow and turbulence could be identified well beyond two valley widths from the downwind edge. Nonnormal wind angles lead to significant along-valley flows within the valley and, even at two valley heights above the valley ridge level, there remains a significant spanwise flow component. Downwind turbulence levels are somewhat lower in this case, but are still considerably higher than in the undisturbed boundary layer. At both flow angles, there are significant recirculation regions within the valleys, starting from mean separation just beyond the leading edge, but the strong spanwise flow in the 45 o case reduces the axial extent of the separated zone. The flow is shown to be in some ways analogous to flow over an isolated hill. Our results usefully enhance the field data and could be used to improve modelling of saltation processes in the field.

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Section: Background and Motivationmentioning

confidence: 99%

Section: Background and Motivationmentioning

confidence: 99%

Section: Background and Motivationmentioning

confidence: 99%

Section: Background and Motivationmentioning

confidence: 99%

Section: Background and Motivationmentioning

confidence: 99%

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Measurements of Flows Over Isolated Valleys

Garvey

Castro

Wiggs

et al. 2005

Boundary-Layer Meteorol

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Atmospheric Dispersion: Complex Terrain

Egan¹,

Snyder²

2006

Encyclopedia of Environmetrics

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Atmospheric dispersion processes in complex terrain are generally more complicated than flows over simple, homogeneous, relatively flat terrain. This is because the nonhomogeneity of the terrain not only alters the airflow fields and the turbulence (diffusion intensities) in both the horizontal and vertical directions, but it also affects the consequences of solar heating and radiative cooling on the development of local circulations and flows. Although important over homogeneous terrain, the vertical profiles of wind velocity and temperature are even more important factors when considering complex terrain.

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Turbulence modeling of atmospheric boundary layer flow over complex terrain: a comparison of models at wind tunnel and full scale

Kasmi¹,

Masson²

2010

Wind Energy

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The aim of this work is to evaluate the performance of two popular k − ϵ turbulence closure schemes for atmospheric boundary layer (ABL) flow over hills and valleys and to investigate the effect of using ABL‐modified model constants. The standard k − ϵ and the RNG k − ϵ models are used to simulate flow over the two‐dimensional analytical shapes from the RUSHIL and RUSHVAL wind tunnel experiments. Furthermore, the mean turbulent flow over the real complex terrain of Blashaval hill is simulated and the results verified with a data set of full‐scale measurements. In general, all models yield similar results. However, use of ABL‐modified constants in both models tends to decrease the predicted velocity and increase the predicted turbulent kinetic energy. Copyright © 2010 John Wiley & Sons, Ltd.

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Flow and dispersion of pollutants within two-dimensional valleys

Cited by 23 publications

References 17 publications

Measurements of Flows Over Isolated Valleys

Measurements of Flows Over Isolated Valleys

Atmospheric Dispersion: Complex Terrain

Turbulence modeling of atmospheric boundary layer flow over complex terrain: a comparison of models at wind tunnel and full scale

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