Premium
The performance of spheroidal infinite elements
Author(s) -
Astley R. J.,
Coyette J.P.
Publication year - 2001
Publication title -
international journal for numerical methods in engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.421
H-Index - 168
eISSN - 1097-0207
pISSN - 0029-5981
DOI - 10.1002/nme.260
Subject(s) - helmholtz equation , ellipsoid , surface (topology) , domain (mathematical analysis) , mathematical analysis , simple (philosophy) , convergence (economics) , type (biology) , bounding overwatch , component (thermodynamics) , scattering , padé approximant , physics , mathematics , geometry , boundary value problem , optics , computer science , quantum mechanics , ecology , philosophy , epistemology , astronomy , artificial intelligence , economics , biology , economic growth
A number of spheroidal and ellipsoidal infinite elements have been proposed for the solution of unbounded wave problems in the frequency domain, i.e solutions of the Helmholtz equation. These elements are widely believed to be more effective than conventional spherical infinite elements in cases where the radiating or scattering object is slender or flat and can therefore be closely enclosed by a spheroidal or an ellipsoidal surface. The validity of this statement is investigated in the current article. The radial order which is required for an accurate solution is shown to depend strongly not only upon the type of element that is used, but also on the aspect ratio of the bounding spheroid and the non‐dimensional wave number. The nature of this dependence can partially be explained by comparing the non‐oscillatory component of simple source solutions to the terms available in the trial solution of spheroidal elements. Numerical studies are also presented to demonstrate the rates at which convergence can be achieved, in practice, by unconjugated‐(‘Burnett’) and conjugated (‘Astley‐Leis’)‐type elements. It will be shown that neither formulation is entirely satisfactory at high frequencies and high aspect ratios. Copyright © 2001 John Wiley & Sons, Ltd.