Faculty Profiles - ISHIHARA Takashi

MISC - ISHIHARA Takashi

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a posteriori test of LES models derived by two-point closures for anisotropic turbulens

Fujimura N., Yamazaki Y., Ishihara T., Kaneda Y.

Meeting abstracts of the Physical Society of Japan 55 ( 1 ) 250 - 250 2000.3

Similarity of triad interactions in the incrtial range of a forced turbulence

Ishihara T., Kaneda Y.

Meeting abstracts of the Physical Society of Japan 55 ( 1 ) 252 - 252 2000.3

25aV-10 A posteriori test of LES models derived by two-point closures

ISHIKAWA K, ISHIHARA T, KANEDA Y

Meeting abstracts of the Physical Society of Japan 54 ( 2 ) 220 - 220 1999.9

25aV-9 A posteriori test of the two-dimensional LES model by Leith

OKAWA S, ISHIHARA T, KANEDA Y

Meeting abstracts of the Physical Society of Japan 54 ( 2 ) 219 - 219 1999.9

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

Y Kaneda, T Ishihara, K Gotoh

PHYSICS OF FLUIDS 11 ( 8 ) 2154 - 2166 1999.8

Language：English Publisher：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 A priori tests of LES models using high resolution DNS database

Ishihara T., Ishikawa K., Kaneda Y.

Meeting abstracts of the Physical Society of Japan 54 ( 1 ) 772 - 772 1999.3

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

Statistics of small-scale structure of homogeneous isotropic turbulence

10ME-S4 131 1999

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

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

Kamen N. Beronov, Takashi Ishihara, Yukio Kaneda

Proceedings of Oxford Kobe Seminars: The Second Scientific Meeting on Systems Engineering and Applied Mathematics 145-151 1998.12

Pade Approximation of Two-point Two-time Lagrangian Correlation in Turbulence

GOTOH K., ISHIHARA T., KANEDA Y.

Meeting abstracts of the Physical Society of Japan 53 ( 2 ) 910 - 910 1998.9

Taylor expansion in powers of time of Lagrangian velocity field in Taylor-Green flow

ISHIHARA Takashi, GOTOH Koji, KANEDA Yukio

17 389 - 390 1998.7

Fine-scale structure of thin vortical layers Reviewed

T Ishihara, Y Kaneda

JOURNAL OF FLUID MECHANICS 364 297 - 318 1998.6

Language：English Publisher：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 Reviewed

Y Kaneda, K Gotoh, T Ishihara

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 67 ( 4 ) 1075 - 1078 1998.4

Language：English Publisher：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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Analysis of stably stratified uniform shear flow turbuleure

NARUSE T., ISHIHARA T., KANEDA Y.

Meeting abstracts of the Physical Society of Japan 53 ( 1 ) 781 - 781 1998.3