| Project/Area Number |
17560051
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Engineering fundamentals
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| Research Institution | Nagoya University |
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Principal Investigator |
ISHIHARA Takashi Nagoya University, Graduate School of Engineering, Associate Professor, 大学院工学研究科, 助教授 (10262495)
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| Co-Investigator(Kenkyū-buntansha) |
KANEDA Yukio Nagoya University, Graduate School of Engineering, Professor, 大学院工学研究科, 教授 (10107691)
ISHII Katsuya Information Technology Center, Professor, 情報連携基盤センター, 教授 (60134441)
YOSHIMATSU Katsunori Nagoya University, Graduate School of Engineering, Research Associate, 大学院工学研究科, 助手 (70377802)
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| Project Period (FY) |
2005 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2006: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2005: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Keywords | high-Reynolds-number turbulence / high-resolution DNS / turbulence modeling / large eddy simulation / non-empiricization / computational science / ラージ・エディ・シミュレーション |
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| Research Abstract |
Recently we performed ultra-scale direct numerical simulations (DNS's) of incompressible homogeneous isotropic turbulence on the Earth Simulator. The number of grid points is up to 4096^3, the size of which is 64 as large as previous DNS. The attained Taylor micro-scale Reynolds number is as high as 1200. We also performed large-scale DNS's of channel turbulence on the vpp5000/56 system of Information technology center at Nagoya University. In this study, for the purpose of developing numerical-simulation methods (modeling) of high-Reynolds turbulence, we have performed fundamental analyses of the large-scale DNS data of turbulence, have developed new methods of high-resolution DNS, and have tested large eddy simulation (LES) models of turbulence based on the high-resolution DNS's of turbulence.
In the fundamental data analyses of turbulence, it is found that the energy transfer T across the wave number k is highly intermittent and the skewness Sand flatness F of T increase with k approximately in power laws in the inertial subrange. It is also found that (i) the singularity exponents a and b that characterize the intermittencies associated with the rate of energy dissipation and the enstrophy, respectively, agree well with each other in the inertial subrange, and (ii) the correlation coefficient between a and b is approximately 1.0 in the inertial subrange.
In the development of high-resolution DNS method of turbulence, we have investigated the applicability of a Sinc-collocation method to the DNS of turbulent channel flow. It is shown that the method gives high accurate results provided that appropriate grid spacing is used. Our study suggests that the Sinc-collocation method can be a possible alternative of the Chebychev-tau method.
In the test of LES models of turbulence, it is found that the optimal LES model for channel turbulence, which was proposed by Moser et al, shows a good performance near wall for large Reynolds number.
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