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タイトル: | Large-Eddy-Simulation Study of the Effects of Building-Height Variability on Turbulent Flows over an Actual Urban Area |
著者: | Yoshida, Toshiya Takemi, Tetsuya https://orcid.org/0000-0002-7596-2373 (unconfirmed) Horiguchi, Mitsuaki |
著者名の別形: | 吉田, 敏哉 竹見, 哲也 堀口, 光章 |
キーワード: | Actual urban building Large-eddy simulation Atmospheric turbulence Roughness parameter Reynolds stress Quadrant analysis |
発行日: | Jul-2018 |
出版者: | Springer Netherlands |
誌名: | Boundary-Layer Meteorology |
巻: | 168 |
号: | 1 |
開始ページ: | 127 |
終了ページ: | 153 |
抄録: | Large-eddy simulation (LES) is used to investigate the effects of building-height variability on turbulent flows over an actual urban area, the city of Kyoto, which is reproduced using a 2-m resolution digital surface dataset. Comparison of the morphological characteristics of Kyoto with those of European, North American, and other Japanese cities indicates a similarity to European cities but with more variable building heights. The performance of the LES model is validated and found to be consistent with turbulence observations obtained from a meteorological tower and from Doppler lidar. We conducted the following two numerical experiments: a control experiment using Kyoto buildings, and a sensitivity experiment in which all the building heights are set to the average height over the computational region hall . The difference of Reynolds stress at height z=2.5h[all] between the control and sensitivity experiments is found to increase with the increase in the plan-area index ( λp ) for λp>0.32 . Thus, values of λp≈0.3 can be regarded as a threshold for distinguishing the effects of building-height variability. The quadrant analysis reveals that sweeps contribute to the increase in the Reynolds stress in the control experiment at a height z=2.5h[all] . The exuberance in the control experiment at height z=0.5h[all] is found to decrease with increase in the building-height variability. Although the extreme momentum flux at height z=2.5h[all] in the control experiment appears around buildings, it contributes little to the total Reynolds stress and is not associated with coherent motions. |
著作権等: | The final publication is available at Springer via https://doi.org/10.1007/s10546-018-0344-8 The full-text file will be made open to the public on 03 March 2019 in accordance with publisher's 'Terms and Conditions for Self-Archiving'. この論文は出版社版でありません。引用の際には出版社版をご確認ご利用ください。 This is not the published version. Please cite only the published version. |
URI: | http://hdl.handle.net/2433/231409 |
DOI(出版社版): | 10.1007/s10546-018-0344-8 |
出現コレクション: | 学術雑誌掲載論文等 |
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