Some Features of the Spatial Structures of the Surface Layer Turbulence in the High Wind Condition

Iwatani, Yoshiharu

doi:10.2151/jmsj1965.55.1_130

Cited by 14 publications

(5 citation statements)

References 18 publications

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“…As based on the observations of Shiotani et al (1976), Iwatani (1977) confirms the dependency of coherence on the distance indicated by Naito and Kondo (1974), and proposes a 2-dimensional form of decay parameter.…”

Section: Introductionsupporting

confidence: 68%

“…Now it is possible to express the empirical relation of horizontal coherence in an arbitrary direction besides the lateral or longitudinal direction, using the suggestions of Hino (1973) and Iwatani (1977 where j=h denotes the arbitrary horizontal direction, and l is the horizontal distance and * the angle between sensor-line and streamwise direction. Finally the empirical formula of horizontal coherence in an arbitrary direction can be obtained by substituting (4.21) in (3.7).…”

Section: Horizontal Coherencementioning

confidence: 99%

“…16 shows isopleths of space correlation parameter *ih(*-1n *ih(l, n)/*) are also plotted in the figure. The dashed curve in the figure (a) (for u component) is the isopleth of *ih=10 evaluated from the empirical form of Iwatani (1977). Both isopleths for u and * components approach the lateral coordinate at a near perpendicular angle and approach the longitudinal coordinate at a small angle.…”

Section: Horizontal Coherencementioning

confidence: 99%

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Three-Dimensional Space Structure of Turbulent Eddy in the Atmospheric Boundary Layer Above the Ocean

Naito¹

1982

Journal of the Meteorological Society of Japan

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Section: Introductionsupporting

confidence: 68%

Section: Horizontal Coherencementioning

confidence: 99%

Section: Horizontal Coherencementioning

confidence: 99%

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Three-Dimensional Space Structure of Turbulent Eddy in the Atmospheric Boundary Layer Above the Ocean

Naito¹

1982

Journal of the Meteorological Society of Japan

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“…* Figure 4 illustrates the relationship between the decay coefficients and the distance; the figure reveals that the relationship can be approximated to be linear on a log-log scale. We thus assume the following expression for coherence: (4) where C and k are constants.…”

Section: Figure 2 Power Spectral Density Of Wind Speed At Sites T Anmentioning

confidence: 99%

Smoothing effects of distributed wind turbines. Part 1. Coherence and smoothing effects at a wind farm

et al. 2004

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Recently there has been a marked increase in wind power generation. From a power system point of view, because a wind turbine is an intermittent generator with large output fluctuation, any increase in the number of wind turbines gives rise to concerns about the adverse effects of wind turbines on power quality. The smoothing effects of wind turbine output fluctuation are of great importance in assessing the impacts of a large number of wind turbines. This article examines smoothing effects at a wind farm. First it presents a summary of wind measurements taken at two locations with six masts over a period of 1 year on both flat and complex terrain.Then the spatial coherence of wind speed is analysed, paying special attention to its dependence on the distance between observation points, wind direction, wind velocity and fluctuation frequency. Approximation equations for coherence of frequency and distance are obtained by applying Davenport's expression to the observed data. Second, coherence between turbine output at a wind farm is investigated; the results indicate that coherence for wind speed and turbine output shows a considerable resemblance. The article also examines smoothing effects at a wind farm using power spectral density through a theoretical approach. The study proves that smoothing effects can be approximated with a lowpass filter and that the effects at a wind farm should not be taken into account for periods of more than 10 min in case of assessing them on the safe side.

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“…The wide variation of kyw may be alleviated by representing the decay parameter as function of the separation as Naito and Kondo (1974) and Iwatani (1977) suggested. But, this may not solve the problem, because even the coherence between zero and 12m points scattered a great deal as shown by solid symbols in Fig.…”

Section: Space Correlations and Turbulent Scalesmentioning

confidence: 99%

Magnitudes and Horizontal Correlations of Vertical Velocities in High Winds

Shiotani

Iwatani

Kuroha

1978

Journal of the Meteorological Society of Japan

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This paper deals with turbulent properties of vertical velocities and wind inclinations at height of 40m in strong winds. In the wind of sea trajectory, the intensity of turbulence was mostly in the range from 0.03-0.04. The ratio of vertical velocity to longitudinal one, that of vertical velocity to friction velocity, and non-dimensional frequency f m at which logarithmic power spectrum had a maximum were in good agreement with those by other investigators. The lateral correlation was small compared with that of longitudinal velocities. It vanished almost at the separation of 35m. When the square root of coherence was expressed by an exponential function, the decay parameter scattered in a wide range but it was estimated from 14-16 on the average. The effect of averaging on peak values and scales of wind inclinations was discussed as engineering application.With increase of averaging time, peak values decreased and lateral scales increased, but the rate of increase was small compared with that of decrease of the peak values.

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Some Features of the Spatial Structures of the Surface Layer Turbulence in the High Wind Condition

Abstract: The present paper deals with the spatial structures of atmospheric turbulence in terms of the coherence and the phase of velocity fluctuations between two points.

Cited by 14 publications

References 18 publications

Three-Dimensional Space Structure of Turbulent Eddy in the Atmospheric Boundary Layer Above the Ocean

Three-Dimensional Space Structure of Turbulent Eddy in the Atmospheric Boundary Layer Above the Ocean

Smoothing effects of distributed wind turbines. Part 1. Coherence and smoothing effects at a wind farm

Magnitudes and Horizontal Correlations of Vertical Velocities in High Winds

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