Faculty Profiles - ISHIHARA Takashi

MISC - ISHIHARA Takashi

Division display >> ／ All the affair displays 1 - 139 of about 139

Direct Numerical Simulations of Navier-Stokes Equation in Astrophysics : The Growth of Dust Grains in Protoplanetary Disk Turbulence Invited

Masayuki Umemura, Takashi Ishihara

39 ( 2 ) 101 - 107 2020.6

Large-scale Direct Numerical Simulations of Homogeneous Isotropic Turbulence Invited

38 ( 2 ) 74 - 78 2019.6

Turbulence Near Interfaces-Modelling and Simulations

J. C. R. Hunt, T. Ishihara, D. Szubert, I. Asproulias, Y. Hoarau, M. Braza

ADVANCES IN FLUID-STRUCTURE INTERACTION 133 283 - 292 2016

高レイノルズ数乱流中の渦の組織構造とその時間発展 Invited Reviewed

ISHIHARA TAKASHI, UNO ATSUYA, MORISHITA KOJI, YOKOKAWA MITSUO, KANEDA YUKIO

ながれ 35 ( 2 ) 109 - 113 2016

Coherent vorticity in turbulent channel flow: a wavelet viewpoint

Katsunori Yoshimatsu, Teluo Sakurai, Kai Schneider, Marie Farge, Koji Morishita, Takashi Ishihara

Proceedings of Ninth International Symposium on Turbulence and Shear Flow Phenomena 2 - 2015.7

自然や人工系の流体シミュレーション Invited

石原卓

パリティ 30 ( 6 ) 34-36 2015.6

18pCW-10 Energy spectrum in high-resolution direct numerical simulations of turbulence

Ishihara T., Morishita K., Yokokawa M., Uno A., Kaneda Y.

Meeting Abstracts of the Physical Society of Japan 70 ( 0 ) 2807 - 2807 2015

一様等方性乱流の直接数値シミュレーションコードの京コンピュータ向け最適化

森下浩二, 横川三津夫, 宇野篤也, 石原卓, 金田行雄

情報処理学会研究報告. [ハイパフォーマンスコンピューティング] 2014 ( 17 ) 1 - 5 2014.12

Language：Japanese Publisher：一般社団法人情報処理学会

現在日本最速のスーパーコンピュータである「京」を用いて,一様等方性乱流の超大規模直接数値シミュレーション (DNS) を実現するために,地球シミュレータ向けに開発された,フーリエ・スペクトル法に基づく一様等方性乱流の DNS コードの「京」への移植,及び最適化を行った.移植の際には,従来の 1 次元分割によるデータ分散手法から,より効率的な All-to-all 通信が可能であると考えられる 2 次元分割による手法へと変更を行った.その結果,「京」の 192×128 ノードを用いて最大格子点数 122883 の超大規模 DNS の実現に成功した.これはプロダクトランとしては世界最大の一様等方性乱流の DNS である.ピーク性能比として,格子点数 61443,81923,122883 の DNS でそれぞれ 3.84%,3.14%,2.24% の実効性能が得られた.また,コードの更なる高効率化のために,乱流 DNS 特有のアルゴリズムに対する最適化を試み,その性能評価を行った.

一様等方性乱流の直接数値シミュレーションコードの京コンピュータ向け最適化

森下浩二, 横川三津夫, 宇野篤也, 石原卓, 金田行雄

情報処理学会研究報告. 計算機アーキテクチャ研究会報告 2014 ( 17 ) 1 - 5 2014.12

Language：Japanese Publisher：一般社団法人情報処理学会

現在日本最速のスーパーコンピュータである「京」を用いて,一様等方性乱流の超大規模直接数値シミュレーション (DNS) を実現するために,地球シミュレータ向けに開発された,フーリエ・スペクトル法に基づく一様等方性乱流の DNS コードの「京」への移植,及び最適化を行った.移植の際には,従来の 1 次元分割によるデータ分散手法から,より効率的な All-to-all 通信が可能であると考えられる 2 次元分割による手法へと変更を行った.その結果,「京」の 192×128 ノードを用いて最大格子点数 122883 の超大規模 DNS の実現に成功した.これはプロダクトランとしては世界最大の一様等方性乱流の DNS である.ピーク性能比として,格子点数 61443,81923,122883 の DNS でそれぞれ 3.84%,3.14%,2.24% の実効性能が得られた.また,コードの更なる高効率化のために,乱流 DNS 特有のアルゴリズムに対する最適化を試み,その性能評価を行った.

高レイノルズ数乱流中の強い渦の組織構造 (偏微分方程式の背後にある確率過程と解の族が示す統計力学的な現象の解析)

石原卓

数理解析研究所講究録 1919 35 - 37 2014.9

高レイノルズ数乱流中の強い渦の組織構造

石原卓

偏微分方程式の背後にある確立過程と解の族が示す統計力学的な現象の解析 Stochastic Processes and Statistical Phenomena behind RDFs RIMS共同研究報告集 ( 1919 ) 35-37 2014

Dynamic Geometrical Analysis of High-Vorticity Regions in Isotropic Turbulence

Hattori Yuji, Ishihara Takashi

Meeting abstracts of the Physical Society of Japan 68 ( 2 ) 228 - 228 2013.8

Small scale universality and spectral characteristics in turbulent flows Reviewed

Yukio Kaneda, Koji Morishita, Takashi Ishihara

Proceedings of TSFP-8 (2013) Poitiers 1 1-6 2013.8

Language：English

A review is given on studies of statistics at small scales in turbulent flows from a view point of universality. It is assumed in the view that the statistics at sufficiently small scales in the absence of mean flow are at a certain kind of local equilibrium state, and the influence of the mean flow may be regarded as a perturbation added to the equilibrium state. This idea has been examined by comparison of spectral characteristics derived by the idea with those in turbulent boundary layers, mixing layers and direct numerical simulations (DNS) of homogeneous turbulent shear flow. The applicability of this idea to turbulent channel flows is discussed in the light of the data of the log-law region in DNS of turbulent channel flows with the friction Reynolds number Ret up to 5120.

Direct Numerical Simulations of Fundamental Turbulent Flows with the World's Largest Number of Grid-points and Application to Modeling of Engineering Turbulent Flows

Annual report of the Earth Simulator Center 149 - 154 2013.4

Conditional analysis of statistics obtained near the turbulent-nonturbulent interface of turbulent boundary layers

T. Ishihara, H. Ogasawara

Proceedings of ERCOFTAC SYMPOSIUM on Unsteady Separation in Fluid-Structure Interaction 399-403 2013

Study of two elements constituting turbulence by a multifractal theory for probability density functions - Through the analyses of 4096(3) DNS

T. Arimitsu, N. Arimitsu, K. Takechi, Y. Kaneda, T. Ishihara

IC-MSQUARE 2012: INTERNATIONAL CONFERENCE ON MATHEMATICAL MODELLING IN PHYSICAL SCIENCES 410 ( 1 ) 012083 2013

Language：English Publisher：IOP PUBLISHING LTD

The probability density functions (PDFs) of energy dissipation rates created from the whole of the DNS region of the size 4096(3) (named whl-PDFs) for various sizes of coarse graining areas are analyzed by multifractal PDF theory (MPDFT). Furthermore, other PDFs named max-PDF and mm-PDF for various sizes of coarse graining areas, created respectively from the partial DNS regions of the size 512(3) with maximum and minimum enstrophy, are also analyzed by making use of the whl-PDF. It is shown that there is a whl-PDF with an appropriate size of coarse graining area, whose slope of the tail part can adjust the slope of the tail-part of a max-PDF. On the other hand, there is a whl-PDF whose center part can adjust quite accurately the center part of a min-PDF. Note that the partial DNS region with maximum (minimum) enstrophy is the region of maximally dense (rare) vortexes, and therefore contributes mainly to the tail (center) part of the whl-PDF. It is found that these adjustments are systematic with respect to the sizes of coarse graining areas.

DOI： 10.1088/1742-6596/410/1/012083

Volume Penalization法による翼果まわりの流れの数値解析

澤村陽一, 石原卓

生物流体力学及び関連する問題の研究Study of bio-fluid mechanics and related problems RIMS 共同研究報告集 1808 101-120 - 120 2012.9

Improvement of Reality of CG Motion Pictures by Hydrodynamic Effects: Effects of Turbulence Reviewed

Takashi Ishihara, Yuji Hattori

Ninth International Conference on Flow Dynamics - ( - ) - 2012.9

4D visualization of isotropic turbulence and dynamics of high-enstrophy structures Reviewed

Yuji Hattori, Takashi Ishihara

USB Proceedings of JSST 2012 International Conference on Simulation Technology - ( - ) 170-174 2012.9

Interactive visualizations of the large-scale data generated by the DNS of isotropic turbulence on 4096³ grid points Reviewed

Takashi Ishihara, Kensaku Mori

USB Proceedings of JSST 2012 International Conference on Simulation Technology - ( - ) 175-177 2012.9

19aAA-11 Analysis of 4096^3DNS turbulence by Multifractal PDF theory

Takechi K., Arimitsu N., Arimitsu T., Kaneda Y., Ishihra T.

Meeting abstracts of the Physical Society of Japan 67 ( 2 ) 240 - 240 2012.8

Velocity-Dependent Actomyosin ATPase Cycle Revealed by In Vitro Motility Assay with Kinetic Analysis Reviewed

Masaaki K. Sato, Takashi Ishihara, Hiroto Tanaka, Akihiko Ishijima, Yuichi Inoue

BIOPHYSICAL JOURNAL 103 ( 4 ) 711 - 718 2012.8

Language：English Publisher：CELL PRESS

The actomyosin interaction plays a key role in a number of cellular functions. Single-molecule measurement techniques have been developed to study the mechanism of the actomyosin contractile system. However, the behavior of isolated single molecules does not always reflect that of molecules in a complex system such as a muscle fiber. Here, we developed a simple method for studying the kinetic parameters of the actomyosin interaction using small numbers of molecules. This approach does not require the specialized equipment needed for single-molecule measurements, and permits us to observe behavior that is more similar to that of a complex system. Using an in vitro motility assay, we examined the duration of continuous sliding of actin filaments on a sparsely distributed heavy meromyosin-coated surface. To estimate the association rate constant of the actomyosin motile system, we compared the distribution of experimentally obtained duration times with a computationally simulated distribution. We found that the association rate constant depends on the sliding velocity of the actin filaments. This technique may be used to reveal new aspects of the kinetics of various motor proteins in complex systems.

DOI： 10.1016/j.bpj.2012.07.014

OS3-7 Numerical Analysis of Effect of Intermediate Species Diffusion on Low Temperature Oxidation Process in a Homogeneous n-Heptane Mixture(OS3 Application of chemical kinetics to combustion modeling,Organized Session Papers)

Teraji Atsushi, Ishihara Takashi, Kaneda Yukio

The ... international symposium on diagnostics and modeling of combustion in internal combustion engines 2012 ( 8 ) 152 - 157 2012.7

Language：English Publisher：The Japan Society of Mechanical Engineers

A two-dimensional direct numerical simulation (DNS) was applied to investigate the autoignition process of an n-heptane/air mixture. The diffusion of intermediate species was studied in terms of the influence on the ignition delay period and the chemical reaction process. A simplified reaction mechanism was used in this study. The influence of turbulence was investigated by comparing the results of a zero-dimensional simulation and two-dimensional direct simulation of a non-turbulence condition. It was found that the ignition delay period was strongly affected by the different diffusion rates of intermediate species. It was shown that the outflow of OH radicals having a larger diffusion coefficient reduces the reaction rate at the high temperature point. In contrast, the reaction rate was enhanced by the influx of OH radicals at the low temperature point.

Numerical Analysis of Effect of Intermediate Species Diffusion on Low Temperature Oxidation Process in a Homogeneous n-Heptane Mixture Reviewed

Atsushi Teraji, Takashi Ishihara, Yukio Kaneda

Proc. COMODIA 2012 - ( - ) 152-157 - 157 2012

Language：English

A two-dimensional direct numerical simulation (DNS) was applied to investigate the autoignition process of an n-heptane/air mixture. The diffusion of intermediate species was studied in terms of the influence on the ignition delay period and the chemical reaction process. A simplified reaction mechanism was used in this study. The influence of turbulence was investigated by comparing the results of a zero-dimensional simulation and two-dimensional direct simulation of a non-turbulence condition. It was found that the ignition delay period was strongly affected by the different diffusion rates of intermediate species. It was shown that the outflow of OH radicals having a larger diffusion coefficient reduces the reaction rate at the high temperature point. In contrast, the reaction rate was enhanced by the influx of OH radicals at the low temperature point. Copyright © 2012 by the Japan Society of Mechanical Engineers.

Energy Dissipation Rate and Energy Spectrum in High Resolution Direct Numerical Simulations of Turbulence in a Periodic Box(Special Reviews by RONBUN - Prize Award)

KANEDA Yukio, ISHIHARA Takashi, YOKOKAWA Mitsuo, ITAKURA Ken'ichi, UNO Atsuya, Yukio KANEDA, Takashi ISHIHARA, Mitsuo YOKOKAWA, Ken'ichi ITAKURA, Atsuya UNO, Center for General Education Aichi Institute of Technology, Graduate School of Engineering Nagoya University

31 ( 3 ) 241-244 - 244 2012

23pGS-1 Analysis of 4096^3DNS turbulence by Multifractal PDF theory

Arimitsu N., Takechi K., Arimitsu T., Kaneda Y., Ishihara T.

Meeting abstracts of the Physical Society of Japan 66 ( 2 ) 279 - 279 2011.8

25pTC-16 Analysis of 4096^3DNS turbulence by Multifractal PDF theory

Arimitsu N., Takechi K., Arimitsu T., Kaneda Y., Ishihra T.

Meeting abstracts of the Physical Society of Japan 66 ( 1 ) 289 - 289 2011.3

Improvement of Reality of CG Motion Pictures by Hydrodynamic Effects Reviewed

Takashi Ishihara, Yuji Hattori

Proceedings of the Eleventh International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration 48-49 2011

Towards a separation of the elements in turbulence via the analyses withing MPDFT

Toshihico Arimitsu, Naoko Arimitsu, Kohei Takechi, Yukio Kaneda, Takashi Ishihara

arXiv.org[cond-mat.sta-mech] 1111 2011

2D Direct Numerical Simulation of Intermediate Species Diffusion in Low Temperature Oxidation Process Reviewed

Atsushi Teraji, Takahiro Morikawa, Takashi Ishihara, Yukio Kaneda

ICDERS 2011 Proceedings - ( - ) - 2011

25pTF-12 乱流の大規模直接数値計算データを用いた4次速度構造関数及び圧力勾配・速度構造関数の解析(25pTF 非圧縮性流体,領域11(統計力学,物性基礎論,応用数学,力学,流体物理))

中西崇仁, 石原卓

日本物理学会講演概要集 65 ( 2 ) 289 - 289 2010.8

Direct Numerical Simulation of High Reynolds Number Isotropic Turbulence : Universality in Small Scale Statistics(<Special Review>Current Status and Future Prospects of Large-Scale Numerical Simulations-Part2) Invited

KANEDA Yukio, ISHIHARA Takashi, Yukio KANEDA, Takashi ISHIHARA, Graduate School of Engineering Nagoya University, Graduate School of Engineering Nagoya University

Nagare 29 ( 2 ) 73-78 - 78 2010.4

Vortical structures and conditional statistics near the turbulent/non-turbulent interface of a mixing layer

Gotoh Takashi, Ishihara Takashi, Kaneda Yukio

2010 127 - 127 2010

Language：Japanese

Vortical structures and conditional statistics near the turbulent/non-turbulent interface of a turbulent mixing layer are studied using the data obtained by direct numerical simulation. We determine the conditional statistics by averaging data at fixed distances relative to the interface and put our emphasis on the possible Reynolds number (Re) dependence of the conditional statistics. Our analysis suggests that the conditionally-averaged spanwise vorticity has a sharp peak near the interface, and also that the width of the peak is approximately 10η irrespective of Re, where η is the Kolmogorov length scale.

Dynamics of hairpin vortex structures in direct numerical simulation of turbulent boundary layer

Ishihara Takashi, Kato Masayuki, Kaneda Yukio

2010 117 - 117 2010

0217 Direct Numerical Simulation of Turbulent Boundary Layer Using a Spectral Method

ISHIHARA Takashi, KATO Masayuki, KANEDA Yukio

Fluids engineering conference ... 2009 123 - 124 2009.11

Language：Japanese Publisher：The Japan Society of Mechanical Engineers

Spectral direct numerical simulations (DNSs) of zero-pressure-gradient turbulent boundary layer along a flat plate are performed using a fringe method. In the DNSs a particular attention is paid to the possible effect of the fringe method on the statistics of turbulent boundary layer. Comparing the results obtained from DNSs of different parameters, we confirmed that there is a region for which similar Re-dependence of the statistics is obtained. DNS results show that Re-dependence of not only velocity statistics but also pressure statistics is quantitatively consistent with experimental results of much higher Re turbulent boundary layers.

28aQC-6 Computational analysis of vortical structures in high resolution DNS of turbulence

Takahashi Kazuki, Ishihara Takashi

Meeting abstracts of the Physical Society of Japan 64 ( 2 ) 218 - 218 2009.8

乱流の大規模DNSデータ解析：速度差の統計の距離依存性とレイノルズ数依存性

石原卓

九州大学応用力学研究所研究集会報告, 20ME-S6 176 2009.5

Universality in Statistics at Small Scales of Turbulence: A Study by High Resolution DNS Reviewed

Yukio Kaneda, Takashi Ishihara

TURBULENCE AND INTERACTIONS 105 55 - 76 2009

Language：English Publishing type：Research paper, summary (national, other academic conference) Publisher：SPRINGER-VERLAG BERLIN

A review is given of the basic idea and some results of data-analysis of recent high-resolution direct numerical simulations (DNSs) of incompressible turbulence in a periodic box with up to 4096(3) grid points. Emphasis is put on the possible universality of small-scale statistics in turbulence at high Reynolds numbers. An analogy of turbulence with systems at or near thermal equilibrium state is also discussed.

DOI： 10.1007/978-3-642-00262-5_3

Direct Numerical Simulation of Turbulent Boundary Layers Using a Fringe Method

Kato Masayuki, Ishihara Takashi, Kaneda Yukio

2009 27 - 27 2009

Language：Japanese

We perform spectral direct numerical simulations (DNSs) of zero-pressure-gradient turbulent boundary layer along a flat plate using a fringe method. In the DNSs a particular attention is paid to the possible effect of the fringe method on the statistics of turbulent boundary layer. Comparing the results obtained from DNSs of different parameters, we confirmed that there is a region for which similar Re-dependence of the statistics is obtained. Visualizations of turbulent boundary layer show that |ω|, |∇p| and |∂p/∂x| have similar structures. This suggest a possibility that structures in high Re turbulent boundary layer may be understood by analyzing experimental data of ∂p/∂x.

Direct numerical simulation of turbulent channel flow at high Reynolds number Reviewed

Koji Morishita, Takashi Ishihara, Yukio Kaneda

Proceedings of International Symposium on Frontiers of Computational Science 2008 2008 165-172 - 159 2008.11

Language：English Publishing type：Research paper, summary (national, other academic conference)

Taylor microscale Reynolds numbers R_λ and one-dimensional energy spectra of the velocity fluctuations in turbulent channel flows are analyzed by using direct numerical simulations with friction Reynolds numbers up to Re_Τ=1280. Special emphasis is put on the dependence of R_λ on the distance from the wall and Re_Τ.

表紙の図について「乱流の大規模シミュレーション結果の対話的可視化」

石原卓, ISHIHARA Takashi

情報連携基盤センターニュース 7 ( 3 ) 2008.8

スーパーコンピュータを使おう(5)

石原卓

名古屋大学情報連携基盤センターニュース 7 ( 3 ) 327-332 2008.8

Multifractal analysis by using high-resolution direct numerical simulation of turbulence Reviewed

Takashi Ishihara, Hirotaka Higuchi

IUTAM SYMPOSIUM ON COMPUTATIONAL PHYSICS AND NEW PERSPECTIVES IN TURBULENCE 4 61 - 66 2008

Language：English Publisher：SPRINGER

Multifractal analysis based on the energy dissipation epsilon and the enstrophy Omega in isotropic turbulence is made by using high-resolution direct numerical simulation of turbulence with the number of grid points up to 20483. The analysis shows that the singularity exponents alpha and alpha' that characterize the intermittencies associated with epsilon and Omega, respectively, agree well with each other in the inertial subrange. This result is consistent with log epsilon(r) and log Omega(r) correlating well with each other for the scale r in the inertial subrange, where the subscript denotes the local average over a cubic domain of size r.

DOI： 10.1007/978-1-4020-6472-2_9

Attempts at computer-aided understanding of turbulence Reviewed

Yukio Kaneda, Takashi Ishihara, Koji Morishita, Yoshinori Mizuno

IUTAM SYMPOSIUM ON COMPUTATIONAL PHYSICS AND NEW PERSPECTIVES IN TURBULENCE 4 49 - 54 2008

Language：English Publisher：SPRINGER

A review is presented on some attempts to understand turbulence by using high-performance computing (HPC). Among them is the study of turbulence by the direct numerical simulation (DNS) of incompressible turbulence in a periodic box with the number of grid points up to 4096(3). The DNS data shed some light on the Reynolds number (Re)-dependence of the statistics of turbulence at high Re and on the intermittency of energy dissipation. HPC is shown to be useful also for solving a multidimensional singular partial differential equation that determines the anomalous scaling of a passive scalar field advected by a random velocity field with an infinitely small correlation time.

DOI： 10.1007/978-1-4020-6472-2_7

Analysis of Lagrangian acceleration by DNS of isotropic turbulence

Takahashi Kazuki, Ishihara Takashi

2008 169 - 169 2008

Language：Japanese

To study the properties of extreme events in Lagrangean acceleration we analyze Lagrangian data obtained from a direct numerical simulation of forced homogeneous isotropic turbulence which was performed on 1024^3 grid points with R 283. The extreme events are known to be trapping events by vortex filaments. Our analysis shows that the extreme Lagrangian accelerations are accompanied by spiral motions whose frequency is about 0.5Τ_η^1 and whose duration is less than about 10Τ_η, where Τ_η is the Kolmogorov time scale. It is found that the extreme events are strongly correlated with time variation of Lagrangian vorticities.

Attempts at Computational Science of Turbulence Invited

KANEDA Yukio, ISHIHARA Takashi

nagare 26 ( 6 ) 375-383 - 383 2007.12

Language：Japanese Publishing type：Article, review, commentary, editorial, etc. (scientific journal) Publisher：The Japan Society of Fluid Mechanics

A review is presented on attempts to understand turbulence by using high-performance computing. An emphasis is puton the study of turbulence by the direct numerical simulation (DNS) of incompressible turbulence in a periodic boxwith the number of grid points up to 4096³. The DNS data shed some light on the basic questions on the statisticsof turbulence at high Reynolds number Re. The statistics include (i) the normalized mean rate of kinetic energydissipation in the limit Re→→, (ii) the energy spectrum in the universal equilibrium range, (iii) intermittency of thenergy dissipation rate, and (iv) energy transfer from large to small scales.

DOI： 10.11426/nagare1982.26.375

22pTW-5 Multifractal analysis of turbulence by high resolution DNS

Higuchi Hirotaka, Ishihara Takashi

Meeting abstracts of the Physical Society of Japan 62 ( 2 ) 296 - 296 2007.8

Small-scale statistics in high-resolution direct numerical simulation of turbulence Reviewed

Yukio Kaneda, Takashi Ishihara

PROGRESS IN TURBULENCE II 109 11 - + 2007

Language：English Publishing type：Research paper, summary (national, other academic conference) Publisher：SPRINGER-VERLAG BERLIN

We performed high-resolution direct numerical simulations (DNSs) of incompressible turbulence in a periodic box with the number of grid points up to 4096(3). The DNS data shed some light on the nature, especially on the possible universality, of small-scale statistics of turbulence at high Reynolds number Re. We report some results of the analysis of the DNS data with an emphasis on the possible dependence of the statistics on Re.

Statistical property of pressure fluctuation in fully developed turbulence Reviewed

Yoshiyuki Tsuji, Takashi Ishihara

IUTAM SYMPOSIUM ON ELEMENTARY VORTICES AND COHERENT STRUCTURES: SIGNIFICANCE IN TURBULENCE DYNAMICS 79 163 - + 2006

Language：English Publisher：SPRINGER

Pressure fluctuation is measured by using a condenser microphone and piezoresistive transducer. In order to confirm the experimental accuracy, measured data are compared with direct numerical simulation. This basic test encourages us to study small-scale statistics from the standpoint of Kohnogorov universal scaling. The power-law exponent and proportional constant of normalized pressure spectrum are discussed. The clear power law with scaling exponent -7/3 is confirmed in the range of R-lambda >= 600. These Reynolds numbers are much larger than those in velocity fluctuation for achieving the Kolmogorov scaling. The spectral constant K-p is not universal but depends on Reynolds number.

DOI： 10.1007/1-4020-4181-0_17

High-resolution direct numerical simulation of turbulence Reviewed

Y Kaneda, T Ishihara

JOURNAL OF TURBULENCE 7 ( 20 ) 1 - 17 2006

Language：English Publishing type：Rapid communication, short report, research note, etc. (scientific journal) Publisher：TAYLOR & FRANCIS LTD

We performed high-resolution direct numerical simulations (DNS) of incompressible turbulence in a periodic box by using a Fourier spectral method with the number of grid points up to 4096(3). The simulations consist of two series: one with k(max)eta similar to 1 ( series 1), and the other with k(max)eta similar to 2 (series 2), where k(max) is the highest wavenumber in each simulation, and. is the Kolmogorov length scale. In the 4096(3) DNS, the Taylor scale Reynolds number R-lambda similar to 1200 and the ratio of L/eta of the integral length scale L to eta is approximately 2200, in series 1. The DNS data analysis reveals simple scaling of various spectra, and also sheds some light on (i) the energy spectrum at high R-lambda, (ii) the asymptotic R-lambda-dependence of the normalized energy dissipation rate, (iii) the anomalous scaling of the spectra of energy dissipation and enstrophy, and so on. After some preliminary remarks on the methods and limitations of the DNS, this paper presents a review of the DNS data analysis. Discussions are also made on some questions invoked by the DNS.

DOI： 10.1080/14685240500256099

AM06-03-002 Multifractal Analysis by Using High-Resolution Direct Numerical Simulation of Turbulence

Ishihara Takashi, Higuchi Hirotaka, Kaneda Yukio

2006 34 - 34 2006

Language：Japanese

Multifractal analysis is performed by using the high-resolution DNS data of turbulence with the number of grid points up to 4096^3. The analysis shows that the so-called generalized dimensions of energy dissipation and enstrophy can be obtained as almost scale-independent expornents provided that the scale is in the inertial subrange. Reynolds number dependence of multifractal measures such as the so-called f(α) spectra is discussed.

Statistics of energy transfer in high-resolution direct numerical simulation of turbulence in a periodic box Reviewed

T Aoyama, T Ishihara, Y Kaneda, M Yokokawa, K Itakura, A Un

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 74 ( 12 ) 3202 - 3212 2005.12

Language：English Publisher：PHYSICAL SOC JAPAN

The statistics of energy transfer is studied by using the data of a series of high-resolution direct numerical simulations of incompressible homogeneous turbulence in a periodic box with the Taylor micro-scale Reynolds number R-lambda and grid points up to approximately 1130 and 4096(3), respectively. The data show that the energy transfer T across the wave number k is highly intermittent and the skewness S and flatness F of T increase with k approximately as S proportional to (kL)(alpha S), F proportional to (kL)(alpha F) in the inertial subrange, where alpha(S) similar to 2/3, alpha(F) similar to 1 and L the characteristic length scale of energy containing eddies. The comparison between the statistics of T, the energy dissipation rate epsilon and its average epsilon(r) over a domain of scale r shows that T is less intermittent than epsilon, while there is a certain similarity between the probability distribution functions of T and epsilon(r).

DOI： 10.1143/JPSJ.74.3202

Box 乱流の大規模 DNS 結果から見た Channel 乱流

石原卓, 長田將明, 金田行雄

京都大学数理解析研究所講究録 1434 ( 1434 ) 188-194 - 194 2005.5

結合コンパクトスキームを用いたチャネル乱流の直接数値シミュレーション

高林大作, 林一樹, 石原卓

豊田研究報告 ( 58 ) 155-160 - 160 2005.5

Energy spectrum in the near dissipation range of high resolution direct numerical simulation of turbulence Reviewed

T Ishihara, Y Kaneda, M Yokokawa, K Itakura, A Uno

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 74 ( 5 ) 1464 - 1471 2005.5

Language：English Publisher：PHYSICAL SOC JAPAN

The energy spectrum in the near dissipation range of turbulence is studied by analyzing the data of a series of high-resolution direct numerical simulations of incompressible homogeneous turbulence in a periodic box with the Taylor micro-scale Reynolds number R-lambda and resolution ranging up to about 675 and 4096(3), respectively. The spectra in the Reynolds number range fit well to the form C(k eta)(alpha) exp(-beta k eta) in the wavenumber range 0.5 less than or similar to k eta less than or similar to 1.5, where eta is the Kolmogorov dissipation length scale and C, alpha and beta are constants independent of k. The values of alpha and beta decrease monotonically with R-lambda, and they are consistent with the conjecture that they approach to constants as R-lambda -> infinity, but the approach, especially that of beta, is slow.

DOI： 10.1143/JPSJ.74.1464

AM05-02-001 Data analysis based on the ultra DNS of turbulence : Energy flux and dissipation in the inertial subrange of turbulence

Ishihara Takashi, Aoyama Tomohiro, Kaneda Yukio

2005 53 - 53 2005

Language：Japanese

Energy flux in turbulence from scales larger than a filter size γ to small scales is given by T(x, t)=-Τ_<ij>S^^-_<ij>, where Τ_<ij> is the subgrid stress and S^^-_<ij> is the resolved strain-rate tensor. The statistics of T is studied by using the data of a series of high-resolution direct numerical simulations of incompressible turbulence in a periodic box with the number of grid points up to 4096^3. The data show that T is highly intermittent and the skewness S and flatness F of T increase with the wavenumber κ(∝1/γ) approximately as S ∝(κL)^<αS> F ∝(κL)^<αF> in the inertial subrange, where α_S and α_F are constants independent of R_λ, and L is the characteristic length scale of energy containing eddies. The relation between the statistics of T, the energy dissipation rate ε and its local average ε_γ over a domain of scale r is also studied; T is less intermittent than ε and there is a certain similarity in the probability distribution functions of T and ε_γ.

Scalability of hybrid programming for a CFD code on the Earth Simulator

K Itakura, A Uno, M Yokokawa, T Ishihara, Y Kaneda

PARALLEL COMPUTING 30 ( 12 ) 1329 - 1343 2004.12

Language：English Publisher：ELSEVIER SCIENCE BV

The Earth Simulator (ES) is an SMP cluster system. There are two types of parallel programming models available on the ES. One is a flat programming model, in which a parallel program is implemented by MPI interfaces only, both within an SMP node and among nodes. The other is a hybrid programming model, in which a parallel program is written by using thread programming within an SMP node and MPI programming among nodes simultaneously. It is generally known that it is difficult to obtain the same high level of performance using the hybrid programming model as can be achieved with the flat programming model.
In this paper, we have evaluated scalability of the code for direct numerical simulation of the Navier-Stokes equations on the ES. The hybrid programming model achieves the sustained performance of 346.9Gflop/s, while the flat programming model achieves 296.4Gfiop/s with 16 PNs of the ES for a DNS problem size of 256 3. For small scale problems, however, the hybrid programming model is not as efficient because of microtasking overhead. It is shown that there is an advantage for the hybrid programming model on the ES for the larger size problems. (C) 2004 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.parco.2004.09.006

13pTD-10 Examination of similarities in the inertial subrange of turbulence through high resolution DNS

Aoyama T., Ishihara T., Kaneda Y

Meeting abstracts of the Physical Society of Japan 59 ( 2 ) 223 - 223 2004.8

13pTD-11 Examination of hypotheses in the Kolmogorov refined turbulence theory through high-resolution DNS

Kutsuna Shuhei, Ishihara Takashi, Kaneda Yukio

Meeting abstracts of the Physical Society of Japan 59 ( 2 ) 223 - 223 2004.8

Ultra Direct Numerical Simulation of Turbulence on the Earth Simulator - Data Analyses- Reviewed

Takashi Ishihara, Yukio Kaneda

Proc. Russia-Japan International Workshop on Turbulence and Instabilities, Moscow, Russia 2004

Ultra direct numerical simulation of turbulence on the earth simulator Reviewed

T Ishihara

COMPUTATIONAL MECHANICS, PROCEEDINGS 369 - 374 2004

Language：English Publishing type：Research paper, summary (national, other academic conference) Publisher：TSINGHUA UNIV PRESS

We recently carried out a series of DNSs of incompressible turbulence with number of grid points up to 4096(3) on the Earth Simulator (ES). The 4096(3) (ultra) DNS is 64 times the size of the largest DNS before the appearance of the ES. The DNSs consist of two groups; one is with K-max eta = 2 R-lambda = 1 and the Taylor micro scale Reynolds number R-lambda = 167 similar to 1131, while the other is with K-max eta = 2 and R-lambda = 94 similar to 675, where K-max is the maximum wave number and eta the Kolmogorov length scale. A review is given on the one-point and two-point statistics of the velocity derivatives, including the fourth-order rotational invariants I-alpha (alpha = 1...4) proposed by Siggia (1981) and the spectra of energy dissipation epsilon, enstrophy omega(2), and pressure p, obtained by the series of the DNSs on the ES. The series of the DNSs suggest that the spectra of epsilon, omega(2), and p exhibited a wave number range in which the spectra scaled with the wave number k as k(-a). Exponent a for p was in good agreement with the value obtained by assuming the joint probability distribution of the velocity field to be Gaussian, while a values for epsilon and omega(2) were very different from the Gaussian approximation values.

High-resolution direct numerical simulation of turbulence - Spectra of fourth-order velocity momenrs Reviewed

Y Kaneda, T Ishihara, M Yokokawa, K Itakura, A Uno

IUTAM SYMPOSIUM ON REYNOLDS NUMBER SCALING IN TURBULENT FLOW 74 155 - 162 2004

Language：English Publishing type：Research paper, summary (national, other academic conference) Publisher：SPRINGER

High-resolution direct numerical simulations (DNSs) of incompressible turbulence based on an alias-free spectral method were performed on the Earth Simulator. Statistics of turbulence are studied by a DNS on 1024(3) grid points with a special emphasis on the spectra of moments fourth order in velocity. A brief review is given on some results of the preliminary analysis of the data of DNSs with up to 2048(3) grid points.

E231 Velocity derivative statistics in direct numerical simulations of turbulence in a periodic box

ISHIHARA Takashi, KANEDA Yukio

2004 392 - 393 2004

Language：Japanese

The data of high resolution direct numerical simulations (DNSs) of incompressible turbulence obeying the Navier-Stokes equations in a periodic box with the number of grid points up to 4096^3 were analyzed to study the one-point statistics of the velocity-derivatives, including probability distribution functions and the fourth-order rotational invariants I_α(α=1,2,3,4) proposed by Siggia (1981). The data suggest that the values of all four I_α(α=1,2,3,4) increase with the Reynolds number R_λ and the ratios I_α/I_l tend to constants with the increase of R_λ, and that they scale with R_λ similarly to each other for large R_λ.

Similarity scaling of pressure fluctuation in turbulence Reviewed

Y Tsuji, T Ishihara

PHYSICAL REVIEW E 68 ( 2 ) 2630968-1-5 2003.8

Language：English Publisher：AMER PHYSICAL SOC

Pressure fluctuation was measured in a turbulent jet using a condenser microphone and piezoresistive transducer. The power-law exponent and proportional constant of normalized pressure spectrum are discussed from the standpoint of Kolmogorov universal scaling. The clear power law with scaling exponent close to -7/3 was confirmed in the range of 600less than or equal toR(lambda). These Reynolds numbers are much larger than those in velocity fluctuation to achieve Kolmogorov scaling. The spectral constant is not universal but depends on Reynolds numbers. Measured pressure probability density functions are compared with direct numerical simulation.

DOI： 10.1103/PhysRevE.68.026309

Anisotropic spectrum of homogeneous turbulent shear flow in a Lagrangian renormalized approximation Reviewed

K Yoshida, T Ishihara, Y Kaneda

PHYSICS OF FLUIDS 15 ( 8 ) 2385 - 2397 2003.8

Language：English Publisher：AMER INST PHYSICS

An analytical study of the anisotropic velocity correlation spectrum tensor in the inertial subrange of homogeneous turbulent shear flow is performed using a Lagrangian renormalized spectral closure approximation. The analysis shows that the spectrum in the asymptotic limit of infinitely large Reynolds numbers Re is determined by two nondimensional universal constants; theoretical estimates for the constants are provided. The anisotropic component of the spectrum at finite Re is more sensitive to large-scale turbulence structures than the isotropic component. A preliminary analysis of the effect of finite Re or the width of the inertial subrange is in qualitative agreement with direct numerical simulations. (C) 2003 American Institute of Physics.

DOI： 10.1063/1.1588307

Spectra of energy dissipation, enstrophy and pressure by high-resolution direct numerical simulations of turbulence in a periodic box Reviewed

T Ishihara, Y Kaneda, M Yokokawa, K Itakura, A Uno

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 72 ( 5 ) 983 - 986 2003.5

Language：English Publisher：PHYSICAL SOC JAPAN

The spectra of the squares of velocity quadratics including the energy dissipation rate epsilon per unit mass, the enstrophy omega(2) and the pressure p were measured using the data obtained from direct numerical simulations (DNSs) of incompressible turbulence in a periodic box with number of grid points up to 2048(3). These simulations were performed using the Earth Simulator computing system. The spectra for epsilon, omega(2) and p exhibited a wave number range in which the spectra scaled with the wave number k as proportional to k(-a). Exponent a for p was about 1.81, which is in good agreement with the value obtained by assuming the joint probability distribution of the velocity field to be Gaussian, while a values for epsilon and omega(2) were about 2/3, and very different from the Gaussian approximation values.

DOI： 10.1143/JPSJ.72.983

大規模DNSによる乱流物理現象の解明

金田行雄, 石原卓

日本流体力学会数値流体力学部門Web会誌 11 ( 2 ) 25-30 2003.5

Energy dissipation rate and energy spectrum in high resolution direct numerical simulations of turbulence in a periodic box Reviewed

Y Kaneda, T Ishihara, M Yokokawa, K Itakura, A Uno

PHYSICS OF FLUIDS 15 ( 2 ) L21 - L24 2003.2

Language：English Publisher：AMER INST PHYSICS

High-resolution direct numerical simulations (DNSs) of incompressible homogeneous turbulence in a periodic box with up to 4096(3) grid points were performed on the Earth Simulator computing system. DNS databases, including the present results, suggest that the normalized mean energy dissipation rate per unit mass tends to a constant, independent of the fluid kinematic viscosity nu as nu-->0. The DNS results also suggest that the energy spectrum in the inertial subrange almost follows the Kolmogorov k(-5/3) scaling law, where k is the wavenumber, but the exponent is steeper than -5/3 by about 0.1. (C) 2003 American Institute of Physics.

DOI： 10.1063/1.1539855

Performance tuning of a CFD code on the earth simulator

K Itakura, A Uno, M Yokokawa, M Saito, T Ishihara, Y Kaneda

NEC RESEARCH & DEVELOPMENT 44 ( 1 ) 115 - 120 2003.1

Language：English Publisher：NEC CORP

High-resolution direct numerical simulations (DNSs) of incompressible turbulence with numbers of grid points up to 2048(3) 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 DNSs based on the spectral method, most of the computation time is consumed in calculating the three-dimensional (3D) Fast Fourier Transform (FFT). In this paper, we tuned the 3D-FFT algorithm for the Earth Simulator and have achieved DNS at 16ATFLOPS on 2048(3) grid points.

Ultra Direct Numerical Simulation of Turbulence on the Earth Simulator Reviewed

Takashi Ishihara

Proc. Japan-Russia Seminar, TIT 2003

Comparison of a spectral method with a higher-order finite difference method in direct numerical simulations of three-dimensional homogeneous turbulence Reviewed

Katsunori Yoshimatsu, Takashi Ishihara, Yukio Kaneda, Satoshi Nakai, Hidetoshi Nishida, Nobuyuki Satafuka

Nippon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B 69 ( 679 ) 541 - 546 2003

Language：Japanese Publisher：Japan Society of Mechanical Engineers

A finite difference method (FDM) is easier and cheaper to use than a spectral method (SM) in flows with complicated geometry, but is inferior to a SM in both accuracy and resolution. In this paper, effects of both accuracy and resolution in a FDM on the quality of incompressible turbulent flow description were studied by comparing a SM with a FDM in direct numerical simulations (DNS) of the three-dimensional freely decaying homogeneous turbulence with 1283 and 2563 grids. We adopted the higher-order method of lines and Fourier spectral method as a FDM and a SM, respectively. The value of the kinematic viscosity was determined so that the minimum value of Kmaxη in time was about 2 in the SM with 2563 grids. Here, Kmax and η are the maximum resolved wavenumber and the Kolmogorov length scale, respectively. The statistical quantities, such as the total energy, the energy dissipation ratio, obtained by the higher-order method of lines were in good agreement with those by the SM. Furthermore, comparing their DNS fields, we found that the performance of the 4th-order method of lines with 2563 grids was comparable to that of the SM with 1283 grids in which the minimum value of Kmaxη in time was about 1.

DOI： 10.1299/kikaib.69.541

LES modelings based on the Lagrangian renormalized approximation Reviewed

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

STATISTICAL THEORIES AND COMPUTATIONAL APPROACHES TO TURBULENCE 203 - 218 2003

Language：English Publishing type：Research paper, summary (national, other academic conference) Publisher：SPRINGER-VERLAG TOKYO

A systematic way for formulating large-eddy simulation (LES) models based on the Lagrangian renormalized approximation is presented. A spectral LES to simulate the energy spectrum and a probabilistic LES to simulate both the energy spectrum and the error spectrum are formulated for 3-dimensional turbulence and 2-dimensional turbulence with the inverse energy cascading range. The derived models axe free from any ad hoc parameters. The models are verified using high resolution numerical simulations with 512(3) grid points for 3-dimension and 1024(3) for 2-dimension.

Predictability of 3D isotropic turbulence - Effect of data assimilation Reviewed

K Hayashi, T Ishihara, Y Kaneda

STATISTICAL THEORIES AND COMPUTATIONAL APPROACHES TO TURBULENCE 239 - 247 2003

Language：English Publishing type：Research paper, summary (national, other academic conference) Publisher：SPRINGER-VERLAG TOKYO

In numerical simulation of turbulent flows, it is usually difficult to obtain exact initial conditions and it is well known that initial uncertainty in high wavenumbers spreads toward large scale through nonlinear dynamics. These imply the limitation of the numerical prediction. We present here a series of numerical experiments to study the effect of data assimilation on the predictability of isotopic 3D turbulence. In the experiment we have two parameters K-c and T to control the data assimilation, where K-c is the maximum of the assimilated wavenumber range and T is the time interval of the assimilation. It is found not only that we can suppress the growth of uncertainty by data assimilation but also that we can reduce it under appropriate conditions on K-c and T. It is also found that there exists a critical K-c* such that if K-c < K-c*, the uncertainty grows for any T.

High resolution DNS of incompressible homogeneous forced turbulence - Time dependence of the statistics Reviewed

T Ishihara, Y Kaneda

STATISTICAL THEORIES AND COMPUTATIONAL APPROACHES TO TURBULENCE 177 - 188 2003

Language：English Publishing type：Research paper, summary (national, other academic conference) Publisher：SPRINGER-VERLAG TOKYO

Results of direct numerical simulation (DNS) of incompressible homogeneous and isotropic forced turbulence with grid points up to 1024 3 are presented with emphasis on the time dependence of the turbulence statistics. The Taylor micro scale Reynolds number at a quasi-stationary state is 283 in the DNS with 1024 3 grid points, and the energy spectrum exhibits an universal equilibrium range. The results suggest that for R-lambda > 280 or so, the energy dissipation rate normalized by the integral length scale and root-mean-square velocity is almost independent of R-lambda and is 0.44 - 0.45.

LES of Stably Stratified Turbulence Reviewed

Kyo Yoshida, Takashi Ishihara, Yukio Kaneda

Proc. International Workshop on Statistical Theories and Computational Approaches to Turbulence 219-228 2002.11

Relative diffusion of a pair of fluid particles in the inertial subrange of turbulence Reviewed

T Ishihara, Y Kaneda

PHYSICS OF FLUIDS 14 ( 11 ) L69 - L72 2002.11

Language：English Publisher：AMER INST PHYSICS

Turbulent diffusion of a pair of fluid particles in 3-dimensional homogeneous and isotropic turbulence was studied using a high-resolution direct numerical simulation (DNS) with 1024(3) grid points. The DNS showed that the mean square of the distance deltax between the two fluid particles grows with time t as <\deltax\(2)>similar toCepsilont(3) in the inertial subrange, which is in agreement with Richardson (1926) and Obukhov (1941), where Capproximate to0.7 and epsilon is the mean dissipation rate per unit mass. A simple Lagrangian closure approximation for <\deltax\(2)> is shown to be in good agreement with the DNS. (C) 2002 American Institute of Physics.

DOI： 10.1063/1.1508443

Scalability Evaluation of Direct Numerical Simulation on Earth Simulator

UNO ATSUYA, ITAKURA KEN'ICHI, YOKOKAWA MITSUO, ISHIHARA TAKASHI, KANEDA YUKIO

IPSJ SIG Notes 91 ( 80 ) 55 - 60 2002.8

Language：Japanese Publisher：Information Processing Society of Japan (IPSJ)

There are two programming models on the shared-memory architecure. One, called the flat programming, is using MPI, and the other, called the hybrid programming, is using MPI and shared-memory models simultaneously. In general, it is difficult that the hybrid programming outperforms the flat programming. In this study, we evaluated a scalability of large-scale direct numerical simulations of the Navier-Stokes equations on the Earth Simulator. As a result, the hybrid programming could outpeform the flat programming on the Earth Simulator. Also, we discuss the tuning strategies to obtain higher performance on the Earth Simulator.

Anisotropic velocity correlation spectrum at small scales in a homogeneous turbulent shear flow Reviewed

T Ishihara, K Yoshida, Y Kaneda

PHYSICAL REVIEW LETTERS 88 ( 15 ) 154501 - 1545014 2002.4

Language：English Publisher：AMER PHYSICAL SOC

A simple theoretical analysis and direct numerical simulations on 512(3) grid points suggest that the velocity correlation spectrum tensor in the inertial subrange of homogeneous turbulent shear flow at high Reynolds number is given by a simple form that is an anisotropic function of the wave vector. The tensor is determined by the rate of the strain tensor of the mean flow, the rate of energy dissipation per unit mass, the wave vector, and two nondimensional constants.

DOI： 10.1103/PhysRevLett.88.154501

25aXB-4 Anisotropic spectrum in homogeneous shear turbulent flow

Ishihara T., Yoshida K., Kaneda Y.

Meeting abstracts of the Physical Society of Japan 57 ( 1 ) 248 - 248 2002.3

25aXB-5 Simulation of 3D homogeneous turbulence:spectral method vs. higher order method of lines

Yoshimatsu K, Ishihara T., Yamazaki Y., Kaneda Y., Nishida H., Nakai S., Satofuka N.

Meeting abstracts of the Physical Society of Japan 57 ( 1 ) 248 - 248 2002.3

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

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

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.

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

乱流の慣性小領域におけるラグランジュ統計

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

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

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

乱流の大規模DNSデータ可視化ツールの開発

石原卓

第4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 61-65 2001

大規模乱流DNSデータの可視化

大野哲也, 森建策, 末永康仁, 石原卓, 石井克哉, 金田行雄

九州大学応用力学研究所研究集会報告 11ME-S3 2000.12

Effect of high wave-number truncation on inertial-range statistics of turbulence.

Yamazaki Y., Ishihara T., Kaneda Y.

Meeting abstracts of the Physical Society of Japan 55 ( 2 ) 223 - 223 2000.9

LES models derived by two-point closures for stratified turbulens

Fujimura N., Ishihara T., Kanea Y.

Meeting abstracts of the Physical Society of Japan 55 ( 2 ) 231 - 231 2000.9

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

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

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

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

Frequency shifts of Roseby waves in the inertial subranges of beta-plaue turbnleure

ISHIHARA T., KANEDA Y.

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

Direct Numerical Simulation of a double-diffusive turbulence

ANDO T., ISHIHARA T., KANEDA Y.

Meeting abstracts of the Physical Society of Japan 53 ( 1 ) 782 - 782 1998.3

Eulerian and Lagrangian statistics in rotating tubuleuce

YAMAZAKI Y., ISHIHARA T., KANEDA Y.

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

6p-YB-4 Numerical simulation of a rotating turbulence

Yamazaki Y., Ishihara T., Kaneda Y.

Meeting abstracts of the Physical Society of Japan 52 ( 2 ) 896 - 896 1997.9

6a-YB-8 Statistics and diffusion in simple-shear turbulence

Tatsumi Nobuyoshi, Naruse Takahiro, Ishihara Takashi, Kaneda Yukio

Meeting abstracts of the Physical Society of Japan 52 ( 2 ) 893 - 893 1997.9

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

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

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

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

　 PREV - NEXT 　

1