MISC - ISHIHARA Takashi

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

　More details

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

researchmap

Large-scale Direct Numerical Simulations of Homogeneous Isotropic Turbulence Invited

38 ( 2 )   74 - 78   2019.6

　More details

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

CiNii Article

CiNii Books

researchmap

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

　More details

Language：English   Publishing type：Rapid communication, short report, research note, etc. (scientific journal)   Publisher：SPRINGER-VERLAG BERLIN  

DOI： 10.1007/978-3-319-27386-0_17

Web of Science

researchmap

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

　More details

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)   Publisher：日本流体力学会  

CiNii Article

CiNii Books

researchmap

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

　More details

Language：English  

Scopus

researchmap

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

　More details

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

researchmap

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

　More details

Language：Japanese   Publisher：The Physical Society of Japan  

DOI： 10.11316/jpsgaiyo.70.2.0_2807

CiNii Article

CiNii Books

researchmap

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

　More details

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.

CiNii Article

CiNii Books

researchmap

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

　More details

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.

CiNii Article

CiNii Books

researchmap

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

　More details

Language：Japanese   Publisher：京都大学  

CiNii Article

CiNii Books

researchmap

Other Link： http://hdl.handle.net/2433/223374

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

　More details

Language：Japanese   Publishing type：Rapid communication, short report, research note, etc. (scientific journal)  

researchmap

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

　More details

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Article

CiNii Books

researchmap

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

　More details

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.

Scopus

researchmap

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

　More details

Language：English   Publisher：Earth Simulator Center, Japan Agency for Marine-Earth Science and Technology  

CiNii Article

CiNii Books

researchmap

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

　More details

Language：English   Publishing type：Rapid communication, short report, research note, etc. (scientific journal)  

researchmap

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

　More details

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

Web of Science

Scopus

researchmap

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

　More details

Language：Japanese   Publishing type：Internal/External technical report, pre-print, etc.   Publisher：京都大学  

CiNii Article

CiNii Books

researchmap

Other Link： http://hdl.handle.net/2433/194442

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

　More details

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

researchmap

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

　More details

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

researchmap

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

　More details

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

researchmap