scispace - formally typeset
Search or ask a question
Topic

Wind profile power law

About: Wind profile power law is a research topic. Over the lifetime, 7312 publications have been published within this topic receiving 163770 citations. The topic is also known as: power law for wind shear.


Papers
More filters
Journal ArticleDOI
20 Mar 2003-Nature
TL;DR: It is found that surface momentum flux levels off as the wind speeds increase above hurricane force, contrary to surface flux parameterizations that are currently used in a variety of modelling applications, including hurricane risk assessment and prediction of storm motion, intensity, waves and storm surges.
Abstract: The transfer of momentum between the atmosphere and the ocean is described in terms of the variation of wind speed with height and a drag coefficient that increases with sea surface roughness and wind speed. But direct measurements have only been available for weak winds; momentum transfer under extreme wind conditions has therefore been extrapolated from these field measurements. Global Positioning System sondes have been used since 1997 to measure the profiles of the strong winds in the marine boundary layer associated with tropical cyclones. Here we present an analysis of these data, which show a logarithmic increase in mean wind speed with height in the lowest 200 m, maximum wind speed at 500 m and a gradual weakening up to a height of 3 km. By determining surface stress, roughness length and neutral stability drag coefficient, we find that surface momentum flux levels off as the wind speeds increase above hurricane force. This behaviour is contrary to surface flux parameterizations that are currently used in a variety of modelling applications, including hurricane risk assessment and prediction of storm motion, intensity, waves and storm surges.

1,314 citations

Journal ArticleDOI
TL;DR: In this article, the aerodynamic properties of wind turbine wakes are studied, focusing on the physics of power extraction by wind turbines, and the main interest is to study how the far wake decays downstream in order to estimate the effect produced in downstream turbines.

1,161 citations

Journal ArticleDOI
TL;DR: In this article, surface layer coefficients for wind profiles, wind stress, and heat flux in typical open sea conditions are briefly reviewed, and the results are presented in a tabular form suitable for climatological calculations from marine wind and temperature data.
Abstract: Surface layer coefficients for wind profiles, wind stress, and heat flux in typical open sea conditions are briefly reviewed. Businger-Dyer flux-gradient relationships and a Charnock wind stress formula fit the empirical data and are dimensionally consistent. These have been solved by an iterative method, and the results are presented in a tabular form suitable for climatological calculations from marine wind and temperature data.

1,101 citations

Journal ArticleDOI
TL;DR: In this article, an analytical solution for the flow of an adiabatic turbulent boundary layer on a uniformly rough surface over a two-dimensional hump with small curvature was presented for the limit L/y 0 → ∞ when h/L 2k2/ln(δ/y0) where L and h are the characteristic length and height of the hump, y0 the roughness length of the surface and δ the thickness of the boundary layer.
Abstract: An analytical solution is presented for the flow of an adiabatic turbulent boundary layer on a uniformly rough surface over a two-dimensional hump with small curvature, e.g. a low hill. The theory is valid in the limit L/y0 → ∞ when h/L 2k2/ln(δ/y0) where L and h are the characteristic length and height of the hump, y0 the roughness length of the surface and δ the thickness of the boundary layer. For rural terrain, taking δ ∼ 600m these conditions imply that 102 < L < 104m and h/L < 0·05. Considerations of the turbulent energy balance suggest that the eddy viscosity distribution for equilibrium flow near a wall may still be used to a good approximation to determine the changes in Reynolds stress. This result is only required in a thin layer adjacent to the surface - in the main part of the boundary layer the perturbation stresses are shown to be negligible and the disturbance to be almost irrotational. The theory shows that for a log-profile upwind the increase in wind speed near the surface of the hill is O((h/L)u0(L)) where u0(L) is the velocity of the incident wind at a height L. Thus the increase in surface winds can be considerably greater than is predicted by potential flow theory based on an upwind velocity u0(h). It is also found that, at the point above the top of a low hill at which the increase in velocity is a maximum, the velocity is approximately equal to the velocity at the same elevation above level ground upwind of the hill. The surface stress is highly sensitive to changes in the surface elevation, being doubled by a slope as small as one in five. The turning of the wind in the Ekman layer may induce a change in direction of the wind above the hill. The main object of this analysis is to show how the changes in wind speed and shear stress are related to the size and shape of the hill and to the roughness of the surface. Some comparisons are made with measurements of the natural wind and wind tunnel flows. These suggest that the theory may be useful in giving rough estimates of the effect of hills on the wind. The theory and the quoted measurements suggest that the present design recommendation for the increase in wind speeds over hills to be used in wind loading calculations may be an underestimate. It is to be hoped that this analysis will encourage more detailed measurements to be made of the wind over hills.

1,035 citations

Journal ArticleDOI
TL;DR: In this article, the effect of wind-generated gravity waves on the airflow is discussed using quasi-linear theory of wind wave generation, and a sensitive dependence of the aerodynamic drag on wave age is found, explaining the scatter in plots of the experimentally observed drag as a function of the wind speed at 10m height.
Abstract: The effect of wind-generated gravity waves on the airflow is discussed using quasi-linear theory of wind-wave generation. In this theory, both the effects of the waves and the effect of air turbulence on the mean wave profile are taken into account. The main result of this theory is that for young wind sea most of the stress in the boundary layer is determined by momentum transfer from wind to waves, therefore, resulting in a strong interaction between wind and waves. For old wind sea there is, however, hardly any coupling. As a consequence, a sensitive dependence of the aerodynamic drag on wave age is found, explaining the scatter in plots of the experimentally observed drag as a function of the wind speed at 10-m height. Also, the growth rate of waves by wind is found to depend on wave age. All this suggests that a proper description of the physics of the momentum transfer at the air–sea interface can only be given by coupling an atmospheric (boundary-layer) model with an ocean-wave prediction ...

858 citations


Network Information
Related Topics (5)
Wind power
99K papers, 1.5M citations
82% related
Boundary layer
64.9K papers, 1.4M citations
80% related
Turbulence
112.1K papers, 2.7M citations
78% related
Climate model
22.2K papers, 1.1M citations
76% related
Greenhouse gas
44.9K papers, 1.3M citations
74% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202357
2022142
202168
202088
201983
2018102