研究者詳細 - 石原　卓

MISC - 石原　卓

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6p-YB-9 乱流場の時間ベキによるTaylor展開

後藤浩二, 石原卓, 金田行雄

日本物理学会講演概要集 52 ( 2 ) 897 - 897 1997年9月

渦面運動に現れる特異性についての数値計算

石原卓

年会一般講演 16 27 - 28 1997年7月

Fine scale structure of thin vortex layers

Takashi Ishihara, Yukio Kaneda

Proc. ICTAM - - 1996年

Singularity Formation in the Shape of a Vortex Sheet in Three Dimensions - Numerical Simulation 査読

Takashi Ishihara, Yukio Kaneda

ESAIM:Proceedings 1 463-479 1996年

一様ストレイン場中の渦層のAnalytic structure

石原卓

数理解析研究所講究録 974 248-259 - 259 1996年

SINGULARITY FORMATION IN 3-DIMENSIONAL MOTION OF A VORTEX SHEET 査読

T ISHIHARA, Y KANEDA

JOURNAL OF FLUID MECHANICS 300 339 - 366 1995年10月

記述言語：英語出版者・発行元：CAMBRIDGE UNIV PRESS

The evolution of a small but finite three-dimensional disturbance on a flat uniform vortex sheet is analysed on the basis of a Lagrangian representation of the motion. The sheet at time t is expanded in a double periodic Fourier series: R(lambda(1),lambda(2),t) = (lambda(1),lambda(2),0) + Sigma(n,m) A(n,m) exp[i(n lambda(1) + delta m lambda(2))], where lambda(1) and lambda(2) are Lagrangian parameters in the streamwise and spanwise directions, respectively, and delta is the aspect ratio of the periodic domain of the disturbance. By generalizing Moore's analysis for two-dimensional motion to three dimensions, we derive evolution equations for the Fourier coefficients A(n,m). The behaviour of A(n,m) is investigated by both numerical integration of a set of truncated equations and a leading-order asymptotic analysis valid at large t. Both the numerical integration and the asymptotic analysis show that a singularity appears at a finite time t, = O(1n epsilon(-1)) where epsilon is the amplitude of the initial disturbance. The singularity is such that A(n,0) = O(t(c)(-1)) behaves like n-(5/2), while A(n)+/-1 = O(epsilon t(c),) behaves like n-(3/2) for large n. The evolution of A(0,m),(spanwise mode) is also studied by an asymptotic analysis valid at large t. The analysis shows that a singularity appears at a finite time t = O(epsilon(-1)) and the singularity is characterized by A(0,2k) proportional to k(5/2) for large k.

DOI： 10.1017/S0022112095003715

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30a-E-9 一様ストレイン場中の微細渦構造のある厳密解

石原卓, 金田行雄

日本物理学会講演概要集. 秋の分科会 1995 ( 4 ) 113 - 113 1995年9月

4a-A-4 渦面の3次元的巻き上がりの特異性の解析と数値計算

石原卓, 金田行雄

日本物理学会講演概要集. 秋の分科会 1994 ( 4 ) 86 - 86 1994年8月

30p-Z-4 渦面の3次元的巻き上がりの数値シミュレーション

石原卓, 金田行雄

日本物理学会講演概要集. 年会 49 ( 4 ) 103 - 103 1994年3月

SPONTANEOUS SINGULARITY FORMATION IN THE SHAPE OF VORTEX SHEET IN 3-DIMENSIONAL FLOW 査読

T ISHIHARA, Y KANEDA

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 63 ( 2 ) 388 - 392 1994年2月

記述言語：英語出版者・発行元：PHYSICAL SOC JAPAN

The three-dimensional motion of a flat uniform vortex sheet slightly perturbed initially in both streamwise and spanwise directions is studied on the basis of a Lagrangian representation of the motion. The vortex sheet at time t is represented as R(lambda1, lambda2, t) (lambda1, lambda2, 0) + SIGMA(n,m) A(n,m) (t) exp i(nlambda1 + mdeltalambda2), where lambda1 and lambda2 are Lagrangian parameters in the streamwise and spanwise directions, respectively, and delta is the aspect ratio of the periodic domain of the disturbance. The behaviour of A(n,0) and A(n,1) is studied by an asymptotic analysis valid at large t. The analysis shows that singularity appears on the sheet at a critical time 0 (In (epsilon1(-1))), where epsilon1 is the initial amplitude of the streamwise disturbance. The singularity is such that A(n,0) behaves like n-5/2 while A(n,1) behaves like n-3/2, for large n. The latter is associated with the vortex stretching intrinsic in three-dimensional dynamics of the sheet.

DOI： 10.1143/JPSJ.63.388

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Spontaneous singularity formation in the shape of vortex sheet in three-dimensional flow-analysis and numerical simulation

石原卓, 金田行雄

数理解析研究所講究録 888 64-72 - 72 1994年

３次元的渦面の運動の解析と数値シミュレーション

石原卓, 金田行雄

京大数理研講究録 866 149-160 1994年

13a-ZA-3 3次元的渦面の運動における解析性の破れ

石原卓, 金田行雄

日本物理学会講演概要集. 秋の分科会 1993 ( 4 ) 83 - 83 1993年9月

TIME MICRO-SCALES OF LAGRANGIAN STRAIN TENSOR IN TURBULENCE 査読

T ISHIHARA, Y KANEDA

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 62 ( 2 ) 506 - 513 1993年2月

STRETCHING AND DISTORTION OF MATERIAL LINE ELEMENTS IN 2-DIMENSIONAL TURBULENCE 査読

T ISHIHARA, Y KANEDA

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 61 ( 10 ) 3547 - 3558 1992年10月

記述言語：英語出版者・発行元：PHYSICAL SOCIETY JAPAN

A study is made of the stretching and distortion of material line elements in turbulence both analytically and numerically. Approximations for the statistics of these processes derived by perturbative expansions are tested by comparison with dynamical simulations in two dimensions. An integral time scale associated with the Lagrangian statistics of the velocity gradients plays a key role in the approximations. A rough estimation of the time scale is obtained by a dynamical short-time analysis by making use of the Navier-Stokes equation.

DOI： 10.1143/JPSJ.61.3547

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乱流中のラグランジュ的およびオイラー的自己速度相関 (統計数理研究所研究活動 (研究会報告乱流の統計理論とその応用))

金田行雄, 石原卓

統計数理 = Proceedings of the Institute of Statistical Mathematics 40 ( 1 ) 55 - 55 1992年6月