Time-Domain Finite-Element Method for the Computation of Three-Dimensional Acoustic Wave Fields in Inhomogeneous Fluids and Solids

摘要

A hybrid method is presented that solves numerically space-time acoustic wave problems in a configuration that may consist of fluid and solid parts. The fluids and solids are taken to be linear, locally and instantaneously reacting, and time invariant in their mechanical behavior. In some bounded domain D(sup sc) the medium is arbitrarily inhomogeneous and anisotropic. The embedding of this domain is a fluid or a solid whose properties are so simple that its Green's function can be constructed by analytical methods. The fluid-domain acoustic wave fields are characterized by their particle velocity and their scalar traction; the solid-domain acoustic wave fields are characterized by their particle velocity and their stress; these quantities are regarded as the fundamental state variables and will henceforth be referred to as the acoustic state quantities. The authors take the bounded domain of numerical computation D such that D(sup sc) is included in D. The computation of the wave fields in D is carried out by a finite-element method that is suited to handle, in particular, the conditions at arbitrarily shaped boundaries and interfaces of the solid/solid, fluid/fluid and the solid/fluid types.