1999 Fiscal Year Final Research Report Summary
Studies on nonequilibrium phenomena in gas flows-New approach by hybrid micro-macro gasdynamics-
| Project/Area Number |
10044151
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| Research Category |
Grant-in-Aid for Scientific Research (B).
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Aerospace engineering
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
SONE Yoshio Kyoto University, Graduate School of Engineering, Professor, 工学研究科, 教授 (80025923)
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| Co-Investigator(Kenkyū-buntansha) |
TAKATA Shigeru Kyoto University, Graduate School of Engineering, Associate Professor, 工学研究科, 助教授 (60271011)
OHWADA Taku Kyoto University, Graduate School of Engineering, Associate Professor, 工学研究科, 助教授 (40223987)
AOKI Kazuo Kyoto University, Graduate School of Engineering, Professor, 工学研究科, 教授 (10115777)
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| Project Period (FY) |
1998 – 1999
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| Keywords | Benard problem / bifurcation / stability / evaporation and condensation / shock wave / vacuum pump / thermal creep flow / cylindrical Couette flow |
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| Research Abstract |
1. The two-dimensional Benard problem for a rarefied gas was studied by both Japanese group (JG) and Italian group (IG). JG found a new bound of the parameter region for a stable solution without a flow, which has not been known in classical fluid dynamics. JG also investigated the stability of multi-roll solutions and clarified the process of transition from unstable multi-roll solutions to stable ones. IG showed an example of the flow with chaotic behavior using the direct simulation Monte Carlo (DSMC) method.
2. JG studied bifurcation of the Couette flow between two coaxial circular cylinders made of the condensed phase of a gas. First, in the case where only the inner cylinder is rotating, the structure of the bifurcation was investigated by analyzing the initial-value problems by the DSMC method, and the relation between the initial conditions and the stable steady solutions was clarified. Next, in the general case, where the outer cylinder is also rotating, a systematic asymptotic
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analysis was carried out under the condition that the rotation of the cylinders is slow and the gas is slightly rarefied. As a result, the structure of the bifurcation was clarified comprehensively, and various new types of bifurcated solution were discovered.
3. JG performed an experimental study of the possibility of a vacuum pump using a rarefied gas flow induced by temperature fields. As a result, a flow consistent with the flow predicted numerically was observed, and the practicality of the pump was demonstrated. JG also summarized the previous results for the rarefied gas flows induced by temperature fields, including this experiment.
4. JG provided a comprehensive and systematic summary of the existing results for flows of a gas condensing onto its condensed phase and gave the information to IG.
5. JG and IG cooperated to study the structure of an infinitely strong shock wave and clarified the singularity in the velocity distribution function by means of a finite-difference method developed by JG. JG also developed a numerical scheme of higher accuracy for time-dependent problems of the Boltzmann equation. Less
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