On the role of polynomials in RBF-FD approximations: III. Behavior near domain boundaries

JOURNAL OF COMPUTATIONAL PHYSICS

卷:380

Article

Bayona, Victor¹  Flyer, Natasha²  Fornberg, Bengt³ 

[1] Univ Carlos III Madrid, Dept Matemat, Madrid 28911, Spain

[2] Natl Ctr Atmospher Res, Analyt & Integrated Machine Learning, Boulder, CO 80305 USA

[3] Univ Colorado, Dept Appl Math, Boulder, CO 80309 USA

关键词: Radial basis functions;    RBF;    RBF-FD;    Cubic polyharmonic splines;    PHS;    Runge's phenomenon;   

DOI  :  10.1016/j.jcp.2018.12.013

来源: Elsevier

【 摘 要 】

Radial basis function generated finite difference (RBF-FD) approximations generalize grid-based regular finite differences to scattered node sets. These become particularly effective when they are based on polyharmonic splines (PHS) augmented with multi-variate polynomials (PHS+poly). One key feature is that high orders of accuracy can be achieved without having to choose an optimal shape parameter and without having to deal with issues related to numerical ill-conditioning. The strengths of this approach were previously shown to be especially striking for approximations near domain boundaries, where the stencils become highly one-sided. Due to the polynomial Runge phenomenon, regular FD approximations of high accuracy will in such cases have very large weights well into the domain. The inclusion of PHS-type RBFs in the process of generating weights makes it possible to avoid this adverse effect. With that as motivation, this study aims at gaining a better understanding of the behavior of PHS+poly generated RBF-FD approximations near boundaries, illustrating it in 1-D, 2-D and 3-D. (C) 2019 Elsevier Inc. All rights reserved.

【 授权许可】

Free