研究者詳細 - 石原　卓

MISC - 石原　卓

分割表示 139 件中 101 - 120 件目／全件表示 >>

25aZE-1 非等方性乱流のLESスペクトル理論モデルのa posterioriテスト

藤村宣昭, 山崎陽介, 石原卓, 金田行雄

日本物理学会講演概要集 55 ( 1 ) 250 - 250 2000年3月

25aZE-9 慣性小領域における3波相互作用の相似性

石原卓, 金田行雄

日本物理学会講演概要集 55 ( 1 ) 252 - 252 2000年3月

25aV-10 3次元乱流のLESスペクトル理論モデルのA posterioriテスト

石川綱一郎, 石原卓, 金田行雄

日本物理学会講演概要集 54 ( 2 ) 220 - 220 1999年9月

25aV-9 Leithによる2次元LESモデルの検証

大川新太朗, 石原卓, 金田行雄

日本物理学会講演概要集 54 ( 2 ) 219 - 219 1999年9月

Taylor expansions in powers of time of Lagrangian and Eulerian two-point two-time velocity correlations in turbulence 査読

Y Kaneda, T Ishihara, K Gotoh

PHYSICS OF FLUIDS 11 ( 8 ) 2154 - 2166 1999年8月

記述言語：英語出版者・発行元：AMER INST PHYSICS

A method is developed for generating the Taylor expansions in powers of the time difference of the Lagrangian and Eulerian two-point two-time velocity correlations in turbulence. The expansions are based on the Taylor series of the Eulerian and Lagrangian velocity fields subject to given dynamics along with initial and boundary conditions. The lowest few coefficients in the expansions enable us to construct approximations to the correlations. An application of the method to turbulence obeying the Navier-Stokes dynamics yields approximations, particularly Padi approximations that agree well with direct numerical simulations of homogeneous isotropic turbulence at moderate Reynolds numbers. The ratios of the second-order to the zeroth-order coefficients of the Taylor series of the Lagrangian and Eulerian correlations give, respectively, the estimates for the Lagrangian and Eulerian micro time scales tau(L) and tau(E). An analysis of a high resolution (512(3) grid points) direct numerical simulation database at large Reynolds number suggests the scalings tau(L)proportional to k(-2/3) and tau(E) proportional to k(-1) for wave numbers k in the inertial subrange. The role of flow structures in turbulence in determining the time scales is also discussed. (C) 1999 American Institute of Physics. [S1070-6631(99)02508-8].

DOI： 10.1063/1.870077

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29p-P-12 乱流の大規模データベースによるLESモデルの検証

石原卓, 石川綱一郎, 金田行雄

日本物理学会講演概要集 54 ( 1 ) 772 - 772 1999年3月

乱流の大規模数値実験

石原卓

九大応力研研究集会「流体方程式の解と縮約解析」 ? 1999年

一様等方乱流中の微細構造の統計(大規模DNSデータベース解析)

石原卓, 山崎陽介, 金田行雄

応用力学研究所研究集会報告 10ME-S4 131 1999年

乱流の大規模数値シミュレーション

石原卓

名古屋大学大型計算機センターニュース 30 ( 4 ) ? 1999年

Numerical Studies of Large Scale Turbulent Flows in Two and Three Dimensions 査読

Kamen N. Beronov, Takashi Ishihara, Yukio Kaneda

Proceedings of Oxford Kobe Seminars: The Second Scientific Meeting on Systems Engineering and Applied Mathematics 145-151 1998年12月

26p-W-8 乱流場のラグランジュ的2時刻2点相関のPade近似

後藤浩二, 石原卓, 金田行雄

日本物理学会講演概要集 53 ( 2 ) 910 - 910 1998年9月

Taylor-Green流のLagrange的時間発展

石原卓, 後藤浩二, 金田行雄

年会一般講演 17 389 - 390 1998年7月

Fine-scale structure of thin vortical layers 査読

T Ishihara, Y Kaneda

JOURNAL OF FLUID MECHANICS 364 297 - 318 1998年6月

記述言語：英語出版者・発行元：CAMBRIDGE UNIV PRESS

A class of exact solutions of the Navier-Stokes equations is derived. Each of them represents the velocity field v = U + u of a thin vortical layer (a planar jet) under a uniform strain velocity field U in three-dimensional infinite space, and provides a simple how model in which nonlinear coupling between small eddies plays a key role in small-scale vortex dynamics. The small-scale structure of the velocity field is studied by numerically analysing the Fourier spectrum of u. It is shown that the Fourier spectrum of rr falls off exponentially with wavenumber k for large k. The Taylor expansion in powers of the coordinate (say y) in the direction perpendicular to the vortical layer suggests that the solution may be well approximated by a function with certain poles in the complex y-plane. The Fourier spectrum based on the singularities is in good agreement with that obtained numerically, where the exponential decay rate is given by the distance of the poles from the real axis of y.

DOI： 10.1017/S0022112098001293

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Taylor expansions and pade approximations of Lagrangian and Eulerian two-time velocity correlations in turbulence 査読

Y Kaneda, K Gotoh, T Ishihara

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 67 ( 4 ) 1075 - 1078 1998年4月

記述言語：英語出版者・発行元：PHYSICAL SOC JAPAN

The time-derivatives up to the Gth-order of Eulerian and Lagrangian velocity fields in homogeneous and isotropic turbulence are computed. The Taylor expansions in powers of the time difference of the Eulerian as well as the Lagrangian two-time velocity correlations, and their Pade approximations are constructed from the time-derivatives. The Pade approximations are found to be in good agreement with direct numerical simulations.

DOI： 10.1143/JPSJ.67.1075

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31p-YW-6 回転乱流中のオイラー的及びラグランジュ的統計

山崎陽介, 石原卓, 金田行雄

日本物理学会講演概要集 53 ( 1 ) 781 - 781 1998年3月