Turbulent wind flow over a low hill

Jackson, P. S.; Hunt, John M.

doi:10.1256/smsqj.43014

Cited by 210 publications

(311 citation statements)

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“…Finnigan et al, 1990), which themselves generally show good agreement with linear theory (e.g. Jackson & Hunt, 1975) for the maximum speed-up near the hill crest. On the other hand, the trends in the various Snyder cases are more subtle, requiring consideration of the effects of streamline curvature.…”

Section: Final Comments and Conclusionsupporting

confidence: 65%

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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: Final Comments and Conclusionsupporting

confidence: 65%

“…Secondly, it is clear that in all cases (except the Snyder V3) the shear stress rises near the surface, as anticipated by linear theories (like those following Jackson & Hunt, 1975). However, the rises do not follow the trend that might at first be anticipated.…”

Section: Resultsmentioning

confidence: 65%

Measurements of Flows Over Isolated Valleys

Garvey

Castro

Wiggs

et al. 2005

Boundary-Layer Meteorol

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show abstract

“…These factors have a strong influence on ventifact scale and distribution. Studies of airflow over hills and dunes (Jackson and Hunt, 1975;Bowen and Lindley, 1977;Taylor, 1977;Lancaster, 1985;Tsoar, 1985;Mulligan, 1988;McKenna Neuman, Lancaster and Nickling, 1997) have led to advances in our understanding of ventifact formation. Wind velocity increases and longer periods of abrasion near hillcrests and in topographic saddles result in scale increases in ventifact features (grooves or flutes) (Figure 21.18).…”

Section: Surface Controls Spatial Variability Feedback and Topographymentioning

confidence: 99%

Wind Erosion in Drylands

Laity

2011

Arid Zone Geomorphology

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“…Consider flow over an isolated hill of height H and length L. L is defined, for convenience, as the horizontal distance from the summit to where the surface elevation is approximately H/2. It has been found (Jackson & Hunt 1975) that H, L, and the ratio H/L are important in determining how the hill affects the flow. For many hills, the ratio of H/L is less than about 1/3, although of course there are steep hills, mountains and cliffs where this is not true.…”

Section: Complex Surfacesmentioning

confidence: 99%

Atmospheric Dispersion and Air Pollution Meteorology

Carruthers¹

2003

Handbook of Atmospheric Science

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Turbulent wind flow over a low hill

Cited by 210 publications

References 0 publications

Measurements of Flows Over Isolated Valleys

Measurements of Flows Over Isolated Valleys

Wind Erosion in Drylands

Atmospheric Dispersion and Air Pollution Meteorology

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