SH波动模拟中透射边界反射放大失稳研究

Reflection amplification instability of the transmitting boundary in SH wave simulation

为进一步研究波动模拟中透射边界存在的反射放大失稳现象,本文针对透射边界在SH波动模拟中的应用,基于透射边界反射系数,揭示了透射边界引发的反射放大失稳规律。论证了此类失稳与具体的内域离散格式无关,仅是人工波速选择不当所致,并给出了合理的人工波速取值范围以避免失稳,同时指出了引起失稳的波动为数值模拟中无意义的成分。本文研究结果适用于一维、二维和三维SH波动,并对于在多维情况下认识和避免反射放大失稳具有重要意义。

Reflection amplification instability may be induced by the transmitting boundary in wave simulation. The work focuses on SH wave simulation and reveals reflection amplification instability based on the reflection coefficient of the transmitting boundary. This type of instability is independent of any interior scheme and is caused solely by the inappropriate artificial wave velocity of the transmitting boundary. Reasonable ranges of artificial wave velocity are given to prevent instability,and waves that cause instability are proven meaningless components of wave simulation. Experimental results are suitable for 1D, 2D,and 3D SH wave motion and are important for understanding and avoiding reflection amplification instability.