Convergence of Lagrange finite elements for the Maxwell eigenvalue problem in two dimensions. (23rd February 2022)

• Record Type: Journal Article
• Authors: Boffi, Daniele; Guzmán, Johnny; Neilan, Michael
• Is Part Of: IMA journal of numerical analysis. Volume 43:Number 2(2023)
• Page Start: 663
• Page End: 691
• Publication Date: 2022-02-23
• Subjects: Maxwell eigenvalues -- Lagrange elements; Numerical analysis -- Periodicals; 519.405
• DOI: 10.1093/imanum/drab104
• Languages: English
• ISSNs: 0272-4979

Abstract

Abstract: We consider finite element approximations of the Maxwell eigenvalue problem in two dimensions. We prove, in certain settings, convergence of the discrete eigenvalues using Lagrange finite elements. In particular, we prove convergence in three scenarios: piecewise linear elements on Powell–Sabin triangulations, piecewise quadratic elements on Clough–Tocher triangulations and piecewise quartics (and higher) elements on general shape-regular triangulations. We provide numerical experiments that support the theoretical results. The computations also show that, on general triangulations, the eigenvalue approximations are very sensitive to nearly singular vertices, i.e., vertices that fall on exactly two 'almost' straight lines.