Local and Modal Radiation Boundary Conditions for Seismo-Acoustic Modeling.(Reannouncement with New Availability Information)

摘要

Effective reflection coefficients have been calculated for various approximateradiation boundary conditions which can be used in conjunction with finite element models. The magnitude of the reflection coefficients give a measure of the accuracy of the boundary condition. More importantly, these effective reflection coefficients are an indication of the contamination of the solution in the interior of the finite element mesh. Using the method outlined by Fix and Marin (1978), one can develop a radiating boundary condition in terms of the propagating modes which could exist at the edge of the computational grid. Such a radiation condition, if it includes all of the modes, gives no artificial reflections from the computational boundary. Progress has been made in incorpirating a modal radiation condition into a finite element model for the scalar case (Murphy et al., 1992) and continues in the elastic case as well. Acoustic waves, Elastic waves, Seismic waves.