1998 Fiscal Year Final Research Report Summary
A Study on the Turbulent Diffusion of Matter and Small Particles by the Random Fourier Modes Method and Stochastic Model
| Project/Area Number |
09650183
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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 |
Fluid engineering
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| Research Institution | Nagoya University |
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Principal Investigator |
SAKAI Yasuhiko Nagoya University Graduate School of Engineering Associate Professor, 工学研究科, 助教授 (20162274)
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| Co-Investigator(Kenkyū-buntansha) |
YOSHIDA Takashi Shinshu University School of Engineering Assistant Professor, 工学部, 講師 (90262857)
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| Project Period (FY) |
1997 – 1998
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| Keywords | Fourier modes / Stochastic Process Model / Mixing / Diffsion / Homogenous Turbulence / Cylinder / Rapid Distortion Theory / Turbulent Pipe Flow |
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| Research Abstract |
This project has been put through according to the initial research plan. The progress and results of the research are summarized in the following,
Object (A) Simulation of plume diffusion field around the body in the three dimensional turbulent flow with a uniform mean velocity
(l) At first, we investigated the plume diffusion field from a point source developed in the grid-turbulence (in case of no body). The numerical simulations have been made by the random Fourier modes method and a Two-particle stochastic model. The simulation results obtained by both models show good agreements with the experimental results.
(2) The turbulent field around the body has been simulated by combining the random Fourier modes method and the rapid distortion theory. By using this simulated turbulent field, the characteristics of a point source plume running perpendicularly into the cylinder have been examined.
Furthermore, the reactive mixing layer in the grid-turbulence has been also simulated by the prob
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ability density function (pdf) method. From this time on, an application of this pdf method to the diffusion around the cylinder has been tried.
Object (B) Development of kinematic method to simulate the complex turbulent flows by the rapid distortion theory, ant its application to the simulation of diffusion fields
Mainly, the analytical solutions of the rapid distortion theory for the homogeneous turbulent shear flows and axisymmetric contraction/expansion flows have been surveyed. Consequently, it was found that in cases of the axisymmetric contraction/expansion flows there exist the temporally stable solutions, but the solution for the homogeneous turbulent shear flows are temporally unstable.
Besides the initial research plan, the diffusion fields of matter in the turbulent pipe flow has been investigated. Further, the fluctuation scalar statistics in the homogeneous isotropic turbulence were estimated from the Lagrangian trajectories of material particles obtained by the direct numerical simulation (DNS). Less
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