Absorbing Boundaries Using Shape Functions Representing Wave Propagation

Abstract

Reflection from artificial boundaries is a source of errors in the numerical analysis of wave propagation. In this paper, based on Clayton and Engquist (1977), an element that absorbs reflections from an artificial boundary in a time domain FEM analysis is presented. By assuming that a wave propagates in one direction at P-wave or S-wave velocity and using the linear acceleration method, the displacement within an element can be determined, and the element matrices derived. Using the presented element as an absorbing boundary, 2-D wave propagation analyses were performed. The presented boundary is demonstrated to efficiently absorb the reflections.