Transition of low Reynolds number flow around Ahmed body of slant angle 𝜃 = 29° and 31°
傾斜角29°と31°のAhmed body周りの低Re流れにおける遷移条件と振動機構
- Delivery
- Available on the other site
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- Publication code
- 20244233
- Paper/Info type
- JSAE Transaction
Vol.55 No.3
- Pages
- 593-600(Total 8 p)
- Date of publication
- May 2024
- Publisher
- JSAE
- Language
- Japanese
Detailed Information
| Category(J) | 論文 Translation |
|---|---|
| Category(E) | Paper |
| Author(J) | 1) 渥美 佑典, 2) 白鳥 英, 3) 郡 逸平, 4) 永野 秀明, 5) 島野 健仁郎 |
| Author(E) | 1) Yusuke Atsumi, 2) Suguru Shiratori, 3) Itsuhei Kohri, 4) Hideaki Nagano, 5) Kenjiro Shimano |
| Affiliation(J) | 1) 東京都市大学, 2) 東京都市大学, 3) 東京都市大学, 4) 東京都市大学, 5) 東京都市大学 |
| Abstract(J) | 自動車模型Ahmed body周りの低Re流れについて傾斜角29度・31度の場合の振動流の発生条件と遷移機構を調査した．振動流への遷移Reは29度でRec=1049，31度でRec=1090であった．振動流の周波数，時間平均場と振動流の空間構造，変動場へのエネルギー供給機構について詳細に分析した． Translation |
| Abstract(E) | A three-dimensional unsteady flow around the Ahmed body at a low Reynolds number (Re) was numerically investigated for the cases of slant angles 𝜃𝜃 𝜃 29° and 31°. The critical Reynolds numbers are determined as Re𝑐𝑐 = 1049 for 𝜃𝜃 𝜃 29° and Re𝑐𝑐 = 1090 for 𝜃𝜃 𝜃 31°. The oscillatory flows appearing near the critical Reynolds number have a single frequency of Strouhal number St ≈ 0.4, and St increases up to St ≈ 0.6 with the increase for Re. At certain large Re, the oscillation of the flow changes to the multi-frequency behavior. The time-averaged flows are mainly composed of a pair of longitudinal vortices shed from the sides of the slant surface and another pair of longitudinal vortices shed from the spanwise center of the slant surface. For the relatively small Re cases, the flows are separated from the slant surface, whereas for the relatively large Re, the separated flow re-attaches downstream and center of the slant surface. The value of Re where the re-attachment takes place is smaller for the case of 𝜃𝜃 𝜃 29°. From the energy analysis based on the Reynolds-Orr equation, the dominant terms and their spatial distribution are investigated. The regions where the energy is strongly supplied from the time-averaged field to the deviated oscillation field appear along the two pairs of longitudinal vortices of the time-averaged field. It was found that the energy supply along vortices at spanwise centers becomes relatively large with the increase of Re. |
