Space–time unfitted finite elements on moving explicit geometry representations

Santiago Badia, Pere A. Martorell*, Francesc Verdugo

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

This work proposes a novel variational approximation of partial differential equations on moving geometries determined by explicit boundary representations. The benefits of the proposed formulation are the ability to handle large displacements of explicitly represented domain boundaries without generating body-fitted meshes and remeshing techniques. For the space discretization, we use a background mesh and an unfitted method that relies on the integration on cut cells. We perform this intersection by using clipping algorithms. To deal with the mesh movement, we pullback the equations to a reference configuration (the spatial mesh at the initial time slab times the time interval) that is constant in time. This way, the geometrical intersection algorithm is only required in 3D, another key property of the proposed scheme. At the end of the time slab, we compute the deformed mesh, intersect the deformed boundary with the background mesh, and consider an exact transfer mechanism between meshes to compute jump terms in the time discontinuous Galerkin integration. The transfer is also computed using geometrical intersection algorithms. We demonstrate the applicability of the method to fluid problems around rotating (2D and 3D) geometries described by oriented boundary meshes. We also provide a set of numerical experiments that show the optimal convergence of the method.

Original languageEnglish
Article number117091
Pages (from-to)1-14
Number of pages14
JournalComputer Methods in Applied Mechanics and Engineering
Volume428
Early online date30 May 2024
DOIs
Publication statusPublished - 1 Aug 2024

Bibliographical note

Publisher Copyright:
© 2024 The Author(s)

Keywords

  • Boundary representations
  • Computational geometry
  • Embedded finite elements
  • Large displacements
  • Space–time discretizations
  • Unfitted finite elements

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