Finite Elements with weighted bases for the fractional Laplacian

Fuente: arXiv
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Main Authors: del Teso, Félix, Fronzoni, Stefano, Gómez-Castro, David
Format: Preprint
Published: 2025
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author del Teso, Félix
Fronzoni, Stefano
Gómez-Castro, David
author_facet del Teso, Félix
Fronzoni, Stefano
Gómez-Castro, David
contents This work presents a numerical study of the Dirichlet problem for the fractional Laplacian $(-Δ)^s$ with $s\in(0,1)$ using Finite Element methods with non-standard bases. Classical approaches based on piece-wise linear basis yield $h^{\frac 1 2}$ convergence rates in the Sobolev-Slobodeckij norm $H^s$ due to the limited boundary regularity of the solution $u(x)$, which behaves like $\operatorname{dist}(x,\mathbb{R}^d\setminus Ω)^s$, where $h$ is the diameter of the mesh elements. To overcome this limitation, we propose a novel Finite Element basis of the form $δ^s \times ($piece-wise linear functions$)$, where $δ$ is any suitably smooth approximation of $\operatorname{dist}(x,\mathbb{R}^d\setminus Ω)$. This exploits the improved regularity of $u/δ^s$, achieving higher convergence rates. Under standard smoothness assumptions the method attains an order $h^{2-s}$ on quasi-uniform meshes, improving the rates with the piece-wise linear basis. We provide a rigorous theoretical error analysis with explicit rates and validate it through numerical experiments.
format Preprint
id arxiv_https___arxiv_org_abs_2511_01727
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Finite Elements with weighted bases for the fractional Laplacian
del Teso, Félix
Fronzoni, Stefano
Gómez-Castro, David
Numerical Analysis
35K55, 35R11, 65N30
This work presents a numerical study of the Dirichlet problem for the fractional Laplacian $(-Δ)^s$ with $s\in(0,1)$ using Finite Element methods with non-standard bases. Classical approaches based on piece-wise linear basis yield $h^{\frac 1 2}$ convergence rates in the Sobolev-Slobodeckij norm $H^s$ due to the limited boundary regularity of the solution $u(x)$, which behaves like $\operatorname{dist}(x,\mathbb{R}^d\setminus Ω)^s$, where $h$ is the diameter of the mesh elements. To overcome this limitation, we propose a novel Finite Element basis of the form $δ^s \times ($piece-wise linear functions$)$, where $δ$ is any suitably smooth approximation of $\operatorname{dist}(x,\mathbb{R}^d\setminus Ω)$. This exploits the improved regularity of $u/δ^s$, achieving higher convergence rates. Under standard smoothness assumptions the method attains an order $h^{2-s}$ on quasi-uniform meshes, improving the rates with the piece-wise linear basis. We provide a rigorous theoretical error analysis with explicit rates and validate it through numerical experiments.
title Finite Elements with weighted bases for the fractional Laplacian
topic Numerical Analysis
35K55, 35R11, 65N30
url https://arxiv.org/abs/2511.01727