Faculty Profiles - ISHIHARA Takashi

MISC - ISHIHARA Takashi

Division display 81 - 100 of about 139 ／ All the affair displays >>

Effects of wavenumber truncation on high-resolution direct numerical simulation of turbulence Reviewed

Y Yamazaki, T Ishihara, Y Kaneda

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 71 ( 3 ) 777 - 781 2002.3

Language：English Publisher：PHYSICAL SOC JAPAN

The effects of wavenumber truncation on the direct numerical simulation (DNS) of incompressible turbulence at high Reynolds numbers using the Fourier spectral method were studied by comparing DNS fields with different truncation wavenumbers, K-max. The comparison suggests that the error due to truncation increases faster at higher wavenumbers, k, and the increase obeys a simple scaling law in the inertial subrange k much less than K-max. Some statistics, such as the energy and dissipation spectra, may remain insensitive to the error, even in the later period, provided that K(max)eta similar to 1 (eta is the Kolmogorov length scale), although DNS fields with different K-max are then essentially uncorrelated to each other.

DOI： 10.1143/JPSJ.71.777

Web of Science

Scopus

researchmap

地球シミュレータによる乱流のUltra Simulation

金田行雄, 石原卓, 横川三津夫, 板倉憲一, 宇野篤也

九大応力研研究集会報告 14ME-S1 90-97 2002

乱流の謎にせまる計算科学

後藤俊幸, 石原卓

パリティ 17 ( 10 ) 27-33 - 33 2002

16.4TFlops direct numerical simulation of turbulence by a Fourier spectral method on the Earth Simulator Reviewed

Mitsuo Yokokawa, Ken'ichi Itakura, Atsuya Uno, Takashi Ishihara, Yukio Kaneda

Proc. IEEE/ACM SC2002 Conf. 2002-November - 2002

Language：English

The high-resolution direct numerical simulations (DNSs) of incompressible turbulence with numbers of grid points up to 40963 have been executed on the Earth Simulator (ES). The DNSs are based on the Fourier spectral method, so that the equation for mass conservation is accurately solved. In DNS based on the spectral method, most of the computation time is consumed in calculating the three-dimensional (3D) Fast Fourier Transform (FFT), which requires huge-scale global data transfer and has been the major stumbling block that has prevented truly high-performance computing. By implementing new methods to efficiently perform the 3D-FFT on the ES, we have achieved DNS at 16.4 Tflops on 20483 grid points. The DNS yields an energy spectrum exhibiting a wide inertial subrange, in contrast to previous DNSs with lower resolutions, and therefore provides valuable data for the study of the universal features of turbulence at large Reynolds number.

DOI： 10.1109/SC.2002.10052

Scopus

researchmap

乱流のUltra Simulation

金田行雄, 石原卓, 横川三津夫, 板倉憲一, 宇野篤也

第６回シミュレーション・サイエンス・シンポジウム及び核融合科学研究所共同研究「大型シミュレーション研究」合同研究会集録NIFS-PROC-52 24-27 2002

地球シミュレータ上の一様等方性乱流シミュレーション

横川三津夫, 斎藤実, 石原卓, 金田行雄

ハイパフォーマンスコンピューティングと計算科学シンポジウムHPCS2002 125-131 2002

Anisotropic spectrum in turbulence and its Reynolds-number denpendency

YOSHIDA Kyo, ISHIHARA Takashi, KANEDA Yukio

2002 388 - 389 2002

Language：Japanese

It was shown by the authors [Phys. Rev. Lett. 88,154501 (2002)] that a perturbational analysis and direct numerical simulations on 512^3 grid points suggest a simple form of the velocity correlation spectrum tensor in the inertial subrange of homogeneous turbulent shear flow at high Reynolds number. It is an anisotropic function of the wavevector and determined by the rate of strain tensor of the mean flow, the energy dissipation per unit mass, and two non-dimensional constants. In this paper, and analysis to estimate the constants based on the Lagrangian renormalized approximation is presented. A preliminary analysis suggests that the anisotropic velocity correlation tensor at a wavenumber is sensitive to its ratio to the lower-end wavenumber of the inertial range.

CiNii Article

CiNii Books

researchmap

Theoretical and numerical study on relative diffusion of particle pairs in isotropic turbulece

Ishihara T., Kaneda Y.

Meeting abstracts of the Physical Society of Japan 56 ( 2 ) 206 - 206 2001.9

Pledictability of three-dimensional isotropic turbulence-Effect of data assimilation

Hayashi K., Ishihara T., Kaneda Y.

Meeting abstracts of the Physical Society of Japan 56 ( 2 ) 206 - 206 2001.9

Frequency shifts of Rossby waves in the inertial subranges of beta-plane turbulence Reviewed

T Ishihara, Y Kaneda

PHYSICS OF FLUIDS 13 ( 8 ) 2338 - 2349 2001.8

Language：English Publisher：AMER INST PHYSICS

Nonlinear interactions between waves and turbulence cause systematic frequency shifts in Rossby waves. The frequency shifts in the inertial subranges of statistically steady beta -plane turbulence were examined theoretically and numerically. The theoretical analysis is based on the Lagrangian closure called the Lagrangian renormalized approximation and predicts that when the beta effect is small, the frequency shifts of Rossby waves are proportional to k(x)/k(4/3) in the inverse energy transfer range, while they are proportional to k(x) with or without a log-correction term in the enstrophy transfer range, depending on the flow conditions, where k(x) is the wave number in the eastward direction. Numerical simulations using 1024(2) grid points of forced beta -plane turbulence that exhibit the inertial subranges, show fairly good agreement with theoretical predictions. (C) 2001 American Institute of Physics.

DOI： 10.1063/1.1384468

石原卓, 金田行雄

京都大学数理解析研究所講究録 1226 ( 1226 ) 86-93 - 93 2001.7

Nonuniversal k(-3) energy spectrum in stationary two-dimensional homogeneous turbulence Reviewed

Y Kaneda, T Ishihara

PHYSICS OF FLUIDS 13 ( 5 ) 1431 - 1439 2001.5

Language：English Publisher：AMER INST PHYSICS

A spectral closure analysis and numerical simulations suggest that there may be a class of two-dimensional turbulence in which the energy spectrum E(k) scales with the wave number k like E(k)=Ak(-3) in the enstrophy transfer range in accordance with the Kraichnan-Leith-Batchelor (KLB) spectrum, but the prefactor A is different from the KLB spectrum and depends in a nontrivial way on the flow conditions at large scales. (C) 2001 American Institute of Physics.

DOI： 10.1063/1.1359187

Web of Science

Scopus

researchmap

Evaluation of predictability in three-dimensional isotropic turbulence

Fujita D., Yoshida K., Ishihara T., Kaneda Y.

Meeting abstracts of the Physical Society of Japan 56 ( 1 ) 294 - 294 2001.3

Predictability in 2-D turbulence and evaluation of LES models

YAMAHIRA T., YOSHIDA K., ISHIHARA T., KANEDA Y.

Meeting abstracts of the Physical Society of Japan 56 ( 1 ) 294 - 294 2001.3

Energy spectrum in the enstrophy transfer range of two-dimensional forced turbulence Reviewed

T Ishihara, Y Kaneda

PHYSICS OF FLUIDS 13 ( 2 ) 544 - 547 2001.2

Language：English Publisher：AMER INST PHYSICS

Numerical simulations of two-dimensional forced turbulence suggest that the enstrophy transfer range energy spectrum E(k) a little steeper than k(-3) is robust in the sense that it may be realized in a wave number range under different run conditions. It is shown that such energy spectra fit well E(k)=C(K)eta (2/3)k(-3)[ln(k/k(1))](-1/3), where C-K is a dimensionless constant, eta the enstrophy transfer rate per unit mass and k(1) a wave number at the bottom of the range. The simulations give C(K)approximate to1.9 in fairly good agreement with the existing theoretical estimates. (C) 2001 American Institute of Physics.

DOI： 10.1063/1.1336149

Web of Science

Scopus

researchmap

Statistics of small-scale structure of homogeneous isotropic turbulence Reviewed

T Ishihara, Y Yamazaki, Y Kaneda

IUTAM SYMPOSIUM ON GEOMETRY AND STATISTICS OF TURBULENCE 59 133 - 138 2001