Hexagonal Smoothness-Increasing Accuracy-Conserving Filtering

Mahsa Mirzargar, Ashok Jallepalli, Jennifer K. Ryan, Robert M. Kirby

Research output: Contribution to journalArticle

5 Citations (Scopus)
7 Downloads (Pure)

Abstract

Discontinuous Galerkin (DG) methods are a popular class of numerical techniques to solve partial differential equations due to their higher order of accuracy. However, the inter-element discontinuity of a DG solution hinders its utility in various applications, including visualization and feature extraction. This shortcoming can be alleviated by postprocessing of DG solutions to increase the inter-element smoothness. A class of postprocessing techniques proposed to increase the inter-element smoothness is SIAC filtering. In addition to increasing the inter-element continuity, SIAC filtering also raises the convergence rate from order k+1k+1 to order 2k+12k+1 . Since the introduction of SIAC filtering for univariate hyperbolic equations by Cockburn et al. (Math Comput 72(242):577–606, 2003), many generalizations of SIAC filtering have been proposed. Recently, the idea of dimensionality reduction through rotation has been the focus of studies in which a univariate SIAC kernel has been used to postprocess a two-dimensional DG solution (Docampo-Sánchez et al. in Multi-dimensional filtering: reducing the dimension through rotation, 2016. arXiv preprint arXiv:1610.02317). However, the scope of theoretical development of multidimensional SIAC filters has never gone beyond the usage of tensor product multidimensional B-splines or the reduction of the filter dimension. In this paper, we define a new SIAC filter called hexagonal SIAC (HSIAC) that uses a nonseparable class of two-dimensional spline functions called hex splines. In addition to relaxing the separability assumption, the proposed HSIAC filter provides more symmetry to its tensor-product counterpart. We prove that the superconvergence property holds for a specific class of structured triangular meshes using HSIAC filtering and provide numerical results to demonstrate and validate our theoretical results.
Original languageEnglish
Pages (from-to)1072–1093
JournalJournal of Scientific Computing
Volume73
Issue number2-3
Early online date11 Aug 2017
DOIs
Publication statusPublished - Dec 2017

Keywords

  • B-splines
  • Hex splines
  • Box splines
  • Smoothness-Increasing Accuracy-Conserving (SIAC) filtering
  • Quasi-interpolation
  • Approximation theory
  • Discontinuous Galerkin

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