局部平面波假定与优化傍轴透射边界

Local plane wave supposition and best-fitting artificial transmitting boundary

本文研究了透射边界及相关问题,指出在近源波动的一般情况下,沿人工边界法向传播的外行波动应为曲面波,但在人工边界点的足够小的时空邻域内,可以将曲平面波近似处理为平面波,亦即采用了局部平面波假定。认为对不同的人工边界点,局部平面波模型中的基本变量是时空变量,是影响透射边界近源精度和稳定性的决定性因素。建立了对物理视波速进行优化求解的数学模型,以及相应的1阶和2阶优化透射边界。

Artificial transmitting boundary and relative problems are studied in the paper.It is indicated that out going wave motion transmitting in the normal direction of the artificial boundary is curved surface wave motion in the near source wave motion cases.But in some nearest time-space neighborhood,the curved surface wave motion can approximately be treated as the plane wave motion,so that the local plane wave motion assumption is adopted.It is considered that the basic variable cx in the local plane wave motion model for the nodal points on the artificial boundary is a time-space variable,and is a key factor in the accuracy and stability of near source wave motion problems.The model for solving the basic variable cx by optimization is set up,and relatively one and two order optimal transmitting boundary is established.