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Delegates are invited to meet and discuss with the poster presenters during the poster presentation sessions between 10:30-11:30 and 16:00-17:00 on Thursday, 19 November 2015.

Lead Session Chair:
Stephan Barth, ForWind - Center for Wind Energy Research, Germany
Takeshi Kamio The University of Tokyo, Japan
Co-authors:
Takeshi Kamio (1) F Makoto Iida (1) Chuichi Arakawa (1)
(1) The University of Tokyo, Tokyo, Japan

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Presenter's biography

Biographies are supplied directly by presenters at EWEA 2015 and are published here unedited

Dr Kamio studies wind energy in The University of Tokyo, especially interested in the turbulent wind simulation on the complex terrain. He has performed several (poster) presentations in the past EWEA events. His recent works is focused on the effects of the atmospheric stability.


Poster

Poster Download poster (10.95 MB)

Abstract

Effects of the atmospheric stability on the LES wind simulation for the complex terrain

Introduction

The prediction of the turbulent wind on terrain is important for wind energy. Although the atmospheric stability is an important factor for the turbulent wind simulation, the researches on it is still less, and its effect on the wind resource estimation or fatigue load evaluation is not clear. In this study, the LES wind simulation is carried out with the vertical temperature gradient which is assumed as the simplified atmospheric stability condition.

Approach

For the turbulent wind simulation, an LES simulation code is used. Since the LES code is originally developed for the atmospheric simulation, the code has many physical models and it is usual for the code to handle the various atmospheric condition. In this study, two case of the atmospheric conditions are calculated and the results are compared. The two cases are (a) neutral condition and (b) unstable condition. An existing site’s complex terrain in Japan is used for these simulations.

Main body of abstract

Two different atmospheric condition cases are calculated by the LES code and the results are compared. The 10 minutes averaged wind speed, turbulence intensity and the power spectrum at 50m above from ground are calculated. The 10 minutes averaged wind speed of the unstable condition case is smaller than the neutral condition case, and the turbulence intensity of the unstable condition case is larger than the neutral condition case. There was no clear difference in the power spectrum.

Conclusion

From the LES simulations with the different atmospheric stability conditions in this study, the decrease of the mean wind speed and the increase of the turbulence intensity are found in the unstable condition case. These results may affect the wind resource assessment or fatigue evaluation. However, in this study, the studied cases are less and the given conditions are not sufficient. Further studies are necessary.


Learning objectives
The atmospheric stability, especially the unstable condition, may affect the wind resource assessment and the fatigue load evaluation. Although it is hard to set the consideration of the atmospheric stability in the wind simulation as the indispensable item, the revision factors for the wind resource assessment or fatigue load evaluation, which is proposed from the researches, will be appropriate.