$L^2$-error analysis of an isoparametric unfitted finite element method for elliptic interface problems
Provides rigorous error analysis for high-order unfitted FEM, which is important for computational scientists solving interface problems with complex geometries.
This paper extends the a priori error analysis of a high-order unfitted finite element method for elliptic interface problems, deriving optimal $L^2$-error bounds in addition to previously established $H^1$-norm bounds.
In the context of unfitted finite element discretizations the realization of high order methods is challenging due to the fact that the geometry approximation has to be sufficiently accurate. Recently a new unfitted finite element method was introduced which achieves a high order approximation of the geometry for domains which are implicitly described by smooth level set functions. This method is based on a parametric mapping which transforms a piecewise planar interface (or surface) reconstruction to a high order approximation. In the paper [C. Lehrenfeld, A. Reusken, \emph{Analysis of a High Order Finite Element Method for Elliptic Interface Problems}, arXiv 1602.02970, Accepted for publication in IMA J. Numer. Anal.] an a priori error analysis of the method applied to an interface problem is presented. The analysis reveals optimal order discretization error bounds in the $H^1$-norm. In this paper we extend this analysis and derive optimal $L^2$-error bounds.