Approximation properties over self-similar meshes of curved finite elements and applications to subdivision based isogeometric analysis

TL;DR

This paper investigates the approximation capabilities of finite element methods on self-similar, recursively parameterized domains, revealing that convergence rates depend mainly on polynomial reproduction rather than element degree, impacting subdivision-based isogeometric analysis.

Contribution

It demonstrates that for self-similar domains, approximation properties depend only on polynomial reproduction, not on element degree, influencing isogeometric analysis strategies.

Findings

$L^ abla$-errors converge at most with rate $h^2$

Approximation depends on polynomial reproduction, not element degree

Implications for subdivision-based isogeometric analysis

Abstract

In this study we consider domains that are composed of an infinite sequence of self-similar rings and corresponding finite element spaces over those domains. The rings are parameterized using piecewise polynomial or tensor-product B-spline mappings of degree $q$ over quadrilateral meshes. We then consider finite element discretizations which, over each ring, are mapped, piecewise polynomial functions of degree $p$. Such domains that are composed of self-similar rings may be created through a subdivision scheme or from a scaled boundary parameterization. We study approximation properties over such recursively parameterized domains. The main finding is that, for generic isoparametric discretizations (i.e., where $p=q$), the approximation properties always depend only on the degree of polynomials that can be reproduced exactly in the physical domain and not on the degree $p$ of the mapped elements. Especially, in general, $L^\infty$-errors converge at most with the rate $h^2$, where $h$ is the mesh size, independent of the degree $p=q$. This has implications for subdivision based isogeometric analysis, which we will discuss in this paper.