Faculty Profiles - ISHIHARA Takashi

MISC - ISHIHARA Takashi

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6p-YB-9 Taylor expansion of the turbulent velocity field in powers of time

Gotoh Koji, Ishihara Takashi, Kaneda Yukio

Meeting abstracts of the Physical Society of Japan 52 ( 2 ) 897 - 897 1997.9

Singularity Formation in Motion of a Vortex Sheet ─Numerical Simulation

ISHIHARA Takashi

16 27 - 28 1997.7

Fine scale structure of thin vortex layers

Takashi Ishihara, Yukio Kaneda

Proc. ICTAM - - 1996

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

Takashi Ishihara, Yukio Kaneda

ESAIM:Proceedings 1 463-479 1996

Analytic Structure of a vortical layer in uniform strain field

974 248-259 - 259 1996

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

T ISHIHARA, Y KANEDA

JOURNAL OF FLUID MECHANICS 300 339 - 366 1995.10

Language：English Publisher：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 An exact solution of Navier-Stokes equation and its small-scale structure

Ishihara T, Kaneda Y.

Abstracts of the meeting of the Physical Society of Japan. Sectional meeting 1995 ( 4 ) 113 - 113 1995.9

4a-A-4 Spontaneous Singularity Formation in the Shape of Vortex Sheet in Three-Dimensional Flow

Ishihara T, Kaneda Y

Abstracts of the meeting of the Physical Society of Japan. Sectional meeting 1994 ( 4 ) 86 - 86 1994.8

30p-Z-4 Numerical Simulation of Three-Dimensional Roll-up of a Vortex Sheet

Ishihara T, Kaneda Y

Abstracts of the meeting of the Physical Society of Japan. Annual meeting 49 ( 4 ) 103 - 103 1994.3

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

T ISHIHARA, Y KANEDA

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 63 ( 2 ) 388 - 392 1994.2

Language：English Publisher：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(Mathematical Fluid Mechanics and Modeling)

RIMS Kokyuroku 888 64-72 - 72 1994

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

13a-ZA-3 The spontaneous breakdown of analyticity in the three dimensional motion of a vortex sheet

Ishihara T., Kaneda Y.

Abstracts of the meeting of the Physical Society of Japan. Sectional meeting 1993 ( 4 ) 83 - 83 1993.9

TIME MICRO-SCALES OF LAGRANGIAN STRAIN TENSOR IN TURBULENCE Reviewed

T ISHIHARA, Y KANEDA

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 62 ( 2 ) 506 - 513 1993.2

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

T ISHIHARA, Y KANEDA

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 61 ( 10 ) 3547 - 3558 1992.10

Language：English Publisher：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 1992.6

28a-ZD-6 乱流中の流体要素の変形の統計理論

石原卓, 金田行雄

年会講演予稿集 47 ( 4 ) 88 - 88 1992.3

Time micro scales of Lagrangian Strain Tensor in Turbulence

800 147-156 - 156 1992

26a-L-1 LINE STRETCHING IN 2-D ISOTROPIC TURBULENCE

Ishihara T

1991 ( 4 ) 76 - 76 1991.3

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