Three-Dimensional Numerical Simulation of Stably Stratified Flows Over a Two-Dimensional Hill : Effect of Stratification on the Non-Periodic Separation and Reattachment of the Flow
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Stably stratified flows over a two-dimensional hill are investigated in a channel of finite depth using a three-dimensional direct numerical simulation (DNS). The present study follows on to our previous two-dimensional DNS studies of stably stratified flows over a hill in a channel of finite depth and provides a more realistic simulation of atmospheric flows than our previous studies. A hill with a constant cross-section in the spanwise (y) direction is placed in a 3-D computational domain. As in the previous 2-D simulations, to avoid the effect of the ground boundary layer that develops upstream of the hill, no-slip conditions are imposed only on the hill surface and the surface downstream of the hill; slip conditions are imposed on the surface upstream of the hill. The simulated 3-D flows are discussed by comparing them to the simulated 2-D flows with a focus on the effect of the stable stratification on the non-periodic separation and reattachment of the flow behind the hill. In neutral (K = 0, where K is a non-dimensional stability parameter) and weakly stable (K = 0.8) conditions, 3-D flows over a hill differ clearly from 2-D flows over a hill mainly because of the three-dimensionality of the flow, that is the development of a spanwise flow component in the 3-D flows. In highly stable conditions (K = 1, 1.3), long-wavelength lee waves develop downstream of the hill in both 2-D and 3-D flows, and the behaviors of the 2-D and 3-D flows are similar in the vicinity of the hill. In other words, the spanwise component of the 3-D flows is strongly suppressed in highly stable conditions, and the flow in the vicinity of the hill becomes approximately two-dimensional in the x and z directions.
収録刊行物
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- 九州大学応用力学研究所所報
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九州大学応用力学研究所所報 139 57-68, 2010-09
九州大学応用力学研究所
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詳細情報 詳細情報について
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- CRID
- 1390009224764102656
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- NII論文ID
- 120005311743
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- NII書誌ID
- AA11459359
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- DOI
- 10.15017/27086
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- HANDLE
- 2324/27086
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- NDL書誌ID
- 11199180
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- ISSN
- 13455664
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- 本文言語コード
- en
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- データソース種別
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- JaLC
- IRDB
- NDL
- CiNii Articles
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- 抄録ライセンスフラグ
- 使用可