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| The 21st Century COE Program | ||
| Center of Excellence for Research and Education on Complex Functional Mechanical Systems | ||
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| The 21st Century COE Program | ||
| Center of Excellence for Research and Education on Complex Functional Mechanical Systems | ||
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| 日時： | 2005年11月16日（水） 14:00〜 |
| 場所： | 京都大学大学院 工学研究科 航空宇宙工学専攻 2階 会議室 |
| 講演者： | Prof. Mikhail S. Ivanov (Head of Computational Aerodynamics Laboratory, Institute of Theoretical and Applied Mechanics, Siberian Division of Russian Academy of Sciences, Novosibirsk, Russia) |
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| 講演題目： | Numerical study of shock-detachment process in hypersonic chemically reacting flow |
| 講演要旨： | Effects of vibrational relaxation and dissociation on the stand-off distance of the bow shock wave on a wedge are numerically examined with the use of the kinetic (DSMC method) and continuum (Navier‐Stokes equations) approaches. A hypersonic flow around the wedge is computed for Knudsen numbers about 0.0005 in a wide range of wedge angles both for a monatomic gas (argon) and a diatomic reacting and non-reacting gas (nitrogen). DSMC computations are based on three different real gas effect models. The kinetic and continuum results for the stand-off distance are in good agreement for argon and non-reacting nitrogen. The influence of vibration-dissociation coupling on the results of numerical simulations was analyzed. Sensitivity of simulation results to chemical reaction rate constants was also estimated. Numerical simulations show that dissociation is responsible for the nonlinear form of the dependence of the stand-off distance on the wedge angle, which qualitatively agrees with available experimental data. |
| 講演者： | Prof. Francis Filbet (Mathematiques pour l'Industrie et la Physique, Universite Paul Sabatier, Toulouse, France) |
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| 講演題目： | Solving the Boltzmann equation in N log_2 N |
| 講演要旨： | We propose fast deterministic algorithms based on spectral methods for the Boltzmann collision operator for a class of interactions including the hard spheres model in dimension 3. These algorithms are implemented for the solution of the Boltzmann equation in dimension 2 and 3, first for homogeneous solutions, then for general nonhomogeneous solutions. The results are compared to explicit solutions, when available, and to Monte-Carlo methods. In particular, the computational cost and accuracy are compared to those of Monte Carlo methods as well as to those of previous spectral methods. Finally, for inhomogeneous solutions, we take advantage of the great computational efficiency of the method to show an oscillation phenomenon of the entropy functional in the trend to equilibrium, which was suggested in the work of Desvillettes-Villani. |
| 京都大学大学院 | 工学研究科 | 機械理工学専攻 | マイクロエンジニアリング専攻 | 航空宇宙工学専攻 |
| 情報学研究科 | 複雑系科学専攻 | |||
| 京都大学 | 国際融合創造センター | |||
| 拠点リーダー | 土屋和雄（工学研究科・航空宇宙工学専攻） | |||