声波正演中一种新的边界条件——双重吸收边界条件

A new kind of absorbing boundary condition for acoustic wave equation-dual absorbing boundary condition.

在声波波动方程有限差分波场数值模拟中,由于计算模型的限制,导致很强的人为边界反射的产生。为了使计算得到的边界波场值更接近真实的边界波场值,往往使用边界条件以减少来自计算区域边界的人为反射能量,使得声波在有限区域传播达到在无限介质中传播的效果。目前,在声波正演中,较常用的一种边界条件是基于标量波动方程旁轴近似理论的吸收边界条件,在此基础上诞生了许多新的边界条件算法。在前人成果的基础上,提出了一种新的吸收边界条件--双重吸收边界条件。该方法将标量波动方程旁轴近似与另一种边界方程通过加权的方式,使所计算的边界波场值比利用通常吸收边界方程计算的边界波场值更接近真实的波场。该方法计算量小,简单易实现,应用于声波正演能得到比利用常规吸收边界条件更好的吸收效果。

In numerical wave simulation of finite difference for acoustic wave equation,due to the limitation of computer model, there inevitably exists strong artificial boundary reflection. In order to make boundary wave field of computation approximate the true wave field value well, people usually minimize artificial reflection from the edges of the domain of computation by boundary condition and make acoustic wave propagation in a limited area efficiently can be used to describe physical behavior in an unbounded domain. Presently, for acoustic wave forwarding, the frequently used boundary conditions are based on paraxial approximations of the scalar wave equation, which has brought about many new methods of computation for boundary condition. On the basis of other a chievements, the paper present a new kind of absorbing boundary condition-dual absorbing boundary condition, they use both paraxial approximations of the scalar wave equation and another boundary equation by weighting to make the boundary wave field of computation approximate the true wave field value better than general boundary conditions. They are computationally inexpensive and simple to apply, and they reduce reflection from boundaries more greatly than general boundary conditions.