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  Bulk scaling in wall-bounded and homogeneous vertical natural convection

Ng, C. S., Ooi, A., Lohse, D., & Chung, D. (2018). Bulk scaling in wall-bounded and homogeneous vertical natural convection. Journal of Fluid Mechanics, 841, 825-850. doi:10.1017/jfm.2018.102.

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アイテムのパーマリンク: https://hdl.handle.net/21.11116/0000-0000-F523-4 版のパーマリンク: https://hdl.handle.net/21.11116/0000-0000-F524-3
資料種別: 学術論文

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 作成者:
Ng, C. S., 著者
Ooi, A., 著者
Lohse, Detlef1, 著者           
Chung, D., 著者
所属:
1Max Planck Institute for Dynamics and Self-Organization, Max Planck Society, ou_2063285              

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キーワード: homogeneous turbulence; turbulence simulation; turbulence theory
 要旨: Previous numerical studies on homogeneous Rayleigh-Benard convection, which is Rayleigh-Benard convection (RBC) without walls, and therefore without boundary layers, have revealed a scaling regime that is consistent with theoretical predictions of bulk-dominated thermal convection. In this so-called asymptotic regime, previous studies have predicted that the Nusselt number (Nu) and the Reynolds number (Re) vary with the Rayleigh number (Ra) according to Nu similar to Ra1/2 and Re similar to Ra1/2 at small Prandtl numbers (Pr). In this study, we consider a flow that is similar to RBC but with the direction of temperature gradient perpendicular to gravity instead of parallel to it; we refer to this configuration as vertical natural convection (VC). Since the direction of the temperature gradient is different in VC, there is no exact relation for the average kinetic dissipation rate, which makes it necessary to explore alternative definitions for Nu, Re and Ra and to find physical arguments for closure, rather than making use of the exact relation between Nu and the dissipation rates as in RBC. Once we remove the walls from VC to obtain the homogeneous set-up, we find that the aforementioned 1/2-power-law scaling is present, similar to the case of homogeneous RBC. When focusing on the bulk, we find that the Nusselt and Reynolds numbers in the bulk of VC too exhibit the 1/2-power-law scaling. These results suggest that the 1/2-power-law scaling may even be found at lower Rayleigh numbers if the appropriate quantities in the turbulent bulk flow are employed for the definitions of Ra, Re and Nu. From a stability perspective, at low-to moderate-Ra, we find that the time evolution of the Nusselt number for homogenous vertical natural convection is unsteady, which is consistent with the nature of the elevator modes reported in previous studies on homogeneous RBC.

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言語: eng - English
 日付: 2018-03-012018-04-25
 出版の状態: 出版
 ページ: -
 出版情報: -
 目次: -
 査読: 査読あり
 識別子(DOI, ISBNなど): DOI: 10.1017/jfm.2018.102
 学位: -

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出版物 1

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出版物名: Journal of Fluid Mechanics
種別: 学術雑誌
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出版社, 出版地: -
ページ: - 巻号: 841 通巻号: - 開始・終了ページ: 825 - 850 識別子(ISBN, ISSN, DOIなど): -