Numerical studies of neutrally stratified planetary boundary-layer flow above gentle topography

Taylor, Peter A.

doi:10.1007/bf00116397

Cited by 78 publications

(35 citation statements)

References 15 publications

(14 reference statements)

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“…This confirms the numerical analysis of Taylor (1977a), who found changes in wind direction of about 20 to 25 deg in some cases, with a maximum change for an angle of attack of 50 or 130 deg. Taylor's calculations and our observations show that with changing wind direction from normal to oblique flow, the influence on mean wind speed decreases but the influence on wind direction increases.…”

Section: Field Overtheembankmentsupporting

confidence: 78%

The turbulent wind flow over an embankment

Hauf

Neumann-Hauf²

1982

Boundary-Layer Meteorol

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Under neutral conditions and with low winds, profiles of mean and turbulent wind components have been measured at various points across an embankment with aspect ratio 0.3. These measurements have been compared with and related to those of undisturbed flow in a horizontal homogeneous area on the windward side. The speed-up ratio, the turbulent and mean kinetic energy and the turbulent shear stress are examined. It is found that the flow stagnates on the windward side, accelerates above the crest, and separates behind the crest. The results show a remarkable dependence on the angle of attack. With an angle smaller than 90", the influence of the embankment on the mean wind field is reduced but is increased on the turbulent part, as lateral gustiness components are amplified. With the incoming flow normal to the embankment, maximum turbulence is found on the top of the ridge near the surface but at greater heights farther downwind. The same is true for the shear stress, but only for oblique flow, whereas for normal flow a minimum is found above the crest and a maximum on the windward side. Therefore, with varying angle of attack the embankment acts in different ways on mean wind, turbulent kinetic energy, and turbulent stress. Although the winds were low, all effects are clearly evident in the data.

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Section: Field Overtheembankmentsupporting

confidence: 78%

The turbulent wind flow over an embankment

Hauf

Neumann-Hauf²

1982

Boundary-Layer Meteorol

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“…Many studies have restricted attention to the problems of gentle orography and neutrally stratified airflow, including the theoretical work of Jackson and Hunt (1975), Taylor (1977) and Sykes (1980), and the wind tunnel experiments of Kurshudyan et al (1980), Britter et al (1981), Pearse et al (1981) and Teunissen et al (1982). Field experiments have been described by Mason and Sykes (1979), Bradley (1980), Mason and King (1985), Mason (1986) and Taylor and Teunissen (1987), and reviewed by .…”

Section: Introductionmentioning

confidence: 99%

A wind tunnel study of turbulent flow over model hills

Gong

Ibbetson

1989

Boundary-Layer Meteorol

111

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Abetrsct. Detailed wind tunnel measurements have been made of mean flow and turbulence over a two-dimensional ridge and a circular hill, both having cosine-squared cross-section and maximum slope about 15". The measurements were made in an artificially thickened neutrally stratified boundary layer, and have been compared with results from linear models and rapid distortion theory as appropriate.Our study shows that linear theory gives generally good predictions of the mean flow on the upwind side of the hills, and especially of the flow speedup at the hill top, but that the turbulence is less well predicted. In particular, the measurements show a major increase in the vertical component of turbulence and in the shear stress on the upwind slope of both the two-and threedimensional hills which is not predicted by either equilibrium or isotropic rapid-distortion theories, although this may be partly due to the effect of streamline curvature. Rapid-distortion theory is successful only in describing the streamwise component of turbulence in the outer region of the flow, while in the upper part of the inner region of the flow, the turbulence measurements show disagreement with both the equilibrium and the rapid-distortion theories. Our experiments also confirm that the equilibrium region is a very thin layer close to the surface, while above this region and below the outer region, there is a transitional region where all terms in the stress equation are important.The measurements over the three-dimensional hill suggest that the mean flow and turbulence are broadly similar to those over the two-dimensional ridge, but with reduced perturbation amplitudes. The major differences between the two cases are found on the upwind slope and in the wake where, respectively, horizontal divergence and convergence of the three-dimensional flow are most pronounced.

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“…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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Numerical studies of neutrally stratified planetary boundary-layer flow above gentle topography

Cited by 78 publications

References 15 publications

The turbulent wind flow over an embankment

The turbulent wind flow over an embankment

A wind tunnel study of turbulent flow over model hills

Wind Erosion in Drylands

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