This paper on "A Benchmark Test of Infinite Elements in Acoustics" was presented at the NAFEMS World Congress on Design, Simulation & Optimisation: Reliability & Applicability of Computational Methods - 9-11 April 1997, Stuttgart, Germany.

Abstract

In Finite Element (FE) calculations of the sound wave emission into free space the external boundaries of the FE model should not introduce artificial reflections. The infinite elements introduce the appropriate boundary conditions at the external boundary of the model.
We present a straightforward testing scheme of the quality of three dimensional FE calculations in acoustics using the infinite elements: For a thin spherical shell acoustic emitter oscillating in one of the characteristic symmetry mode shapes there exist exact analytical three-dimensional solutions for the emitted acoustic pressure waves propagating outwards into infinity. Employing these solutions we tested the beta-version infinite acoustic elements of the finite element programme package ANSYS.
The nature of these solutions allows establishing parametric relations corresponding to a wide class of real-life problems. The related solutions can be also used for testing the FE calculations with infinite elements in electromagnetics, heat- and other diffusion problems and to testing the genuine Boundary Element (BE) Method algorithms.