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ID 115415
タイトル別表記
Various information and complexity measures for analyzing the laminar-turbulent transition process in mixing layer (Analysis of fluctuating vorticity and turbulent energy dissipation rate)
著者
中村, 育雄 名古屋大学
キーワード
Transition
Turbulence
Turbulent flow
Shannon entropy
Permutation entropy
Kolmogorov complexity
Mixing layer
資料タイプ
学術雑誌論文
抄録
In this paper, the laminar-turbulent transition process of a mixing layer downstream of a two-dimensional nozzle exit was analyzed based on various information and complexity measures. Shannon entropy, permutation entropy, and approximated Kolmogorov complexity were also obtained. To obtain the Shannon entropy, the temporal probability distribution of the hot-wire output voltage data was determined and analyzed. In addition to the fluctuating velocity, its time derivative and the square of this derivative were analyzed. The Shannon entropy of the time derivative and its square slightly decreased downstream, in accordance with the increase in the time scale of the turbulence. When the length of the extracted data was constant, the permutation entropy of the time derivative and its square increased around the peripheral region of the mixing layer, in accordance with the intermittent nature of the velocity signals. The region is at the 3-4 times farther from the jet centerline than the region where the fluctuating velocity becomes maximum. When the length of the extracted data was varied in accordance with the integral time scale of turbulence, the permutation entropy initially decreased in the potential core and subsequently increased after the disappearance of the potential core, as the transition progressed. The approximated Kolmogorov complexity of the time derivative and its square were smaller than that of the fluctuating velocity. Owing to the simplification of the data, they slowly increased after the disappearance of the potential core and then quickly decreased after the development of turbulence.
掲載誌名
日本機械学会論文集
ISSN
21879761
出版者
日本機械学会
86
890
開始ページ
20-00130
発行日
2020-10-25
EDB ID
出版社版DOI
出版社版URL
フルテキストファイル
言語
jpn
著者版フラグ
著者版
部局
理工学系