| タイトル | 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 |
| DOI | info:doi/10.15017/27086 |
| 本文（外部サイト） | https://catalog.lib.kyushu-u.ac.jp/opac_download_md/27086/139_p057.pdf |
| 参考URL | http://hdl.handle.net/2324/27086 |
| 著者（英） | Uchida, Takanori; Ohya, Yuji |
| 発行日 | 2013-08-24 |
| 発行機関など | Research Institute for Applied Mechanics, Kyushu University |
| 刊行物名 | 九州大学応用力学研究所所報 |
| 巻 | 139 |
| 開始ページ | 57 |
| 終了ページ | 68 |
| 刊行年月日 | 2010-09 |
| 言語 | eng |
| 内容記述 | 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. |
| キーワード | Finite-difference method; Stably stratified flows; Two-dimensional hill |
| 資料種別 | Departmental Bulletin Paper |
| 著者版フラグ | publisher |
| ISSN | 1345-5664 |
| NCID | AA11459359 |
