| 日時： |
2004年12月15日（水） 16:00〜17:00 |
| 場所： |
京都大学大学院工学研究科 航空宇宙工学専攻 工学部11号館2階 第2講義室 |
| 講演者： |
Dr Werner Koch (DLR Institute of Aerodynamics and Flow Technology, Gottingen, GERMANY) |
| 講演題目： |
Resonances in Open Systems |
| 講演要旨： |
In a short introduction examples of open resonators with acoustic, electromagnetic, elastic and water waves are given. A simple one-dimensional model problem is used to introduce the concept of `leaky modes' which radiate energy. Numerically we employ `perfectly matched layers (PML)' to solve such radiation problems. In wave guide problems so-called `trapped modes' can occur in addition to leaky modes. Trapped modes do not radiate energy and are therefore important in applications. A well known example are the `Parker modes' in wind tunnel testing, heat exchangers or turbomachinery cascades. Finally, as an example of a two-dimensional open resonator we compute the resonances in a classical laser cavity. The acoustic analogon is the `gap tone' problem which is of importance in airframe noise. Two examples of the latter, namely `cavity noise' and `slat noise' are discussed briefly. The latter is still part of ongoing research. |
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