In this work we exploit agglomeration based h-multigrid preconditioners to speed-up the iterative solution of discontinuous Galerkin discretizations of the Stokes and Navier–Stokes equations. As a distinctive feature h-coarsened mesh sequences are generated by recursive agglomeration of a fine grid, admitting arbitrarily unstructured grids of complex domains, and agglomeration based discontinuous Galerkin discretizations are employed to deal with agglomerated elements of coarse levels. Both the expense of building coarse grid operators and the performance of the resulting multigrid iteration are investigated. For the sake of efficiency coarse grid operators are inherited through element-by-element L2 projections, avoiding the cost of numerical integration over agglomerated elements. Specific care is devoted to the projection of viscous terms discretized by means of the BR2 dG method. We demonstrate that enforcing the correct amount of stabilization on coarse grids levels is mandatory for achieving uniform convergence with respect to the number of levels. The numerical solution of steady and unsteady, linear and non-linear problems is considered tackling challenging 2D test cases and 3D real life computations on parallel architectures. Significant execution time gains are documented.

(2017). h-multigrid agglomeration based solution strategies for discontinuous Galerkin discretizations of incompressible flow problems [journal article - articolo]. In JOURNAL OF COMPUTATIONAL PHYSICS. Retrieved from http://hdl.handle.net/10446/112209

h-multigrid agglomeration based solution strategies for discontinuous Galerkin discretizations of incompressible flow problems

Botti, Lorenzo Alessio;Colombo, Alessandro;Bassi, Francesco
2017-01-01

Abstract

In this work we exploit agglomeration based h-multigrid preconditioners to speed-up the iterative solution of discontinuous Galerkin discretizations of the Stokes and Navier–Stokes equations. As a distinctive feature h-coarsened mesh sequences are generated by recursive agglomeration of a fine grid, admitting arbitrarily unstructured grids of complex domains, and agglomeration based discontinuous Galerkin discretizations are employed to deal with agglomerated elements of coarse levels. Both the expense of building coarse grid operators and the performance of the resulting multigrid iteration are investigated. For the sake of efficiency coarse grid operators are inherited through element-by-element L2 projections, avoiding the cost of numerical integration over agglomerated elements. Specific care is devoted to the projection of viscous terms discretized by means of the BR2 dG method. We demonstrate that enforcing the correct amount of stabilization on coarse grids levels is mandatory for achieving uniform convergence with respect to the number of levels. The numerical solution of steady and unsteady, linear and non-linear problems is considered tackling challenging 2D test cases and 3D real life computations on parallel architectures. Significant execution time gains are documented.
articolo
2017
Botti, Lorenzo Alessio; Colombo, Alessandro; Bassi, Francesco
(2017). h-multigrid agglomeration based solution strategies for discontinuous Galerkin discretizations of incompressible flow problems [journal article - articolo]. In JOURNAL OF COMPUTATIONAL PHYSICS. Retrieved from http://hdl.handle.net/10446/112209
File allegato/i alla scheda:
File Dimensione del file Formato  
paperR.pdf

Open Access dal 17/10/2020

Descrizione: link to the formal publication via its DOI 10.1016/j.jcp.2017.07.002
Versione: postprint - versione referata/accettata senza referaggio
Licenza: Creative commons
Dimensione del file 1.78 MB
Formato Adobe PDF
1.78 MB Adobe PDF Visualizza/Apri
1-s2.0-S0021999117305041-main.pdf

Solo gestori di archivio

Versione: publisher's version - versione editoriale
Licenza: Licenza default Aisberg
Dimensione del file 1.52 MB
Formato Adobe PDF
1.52 MB Adobe PDF   Visualizza/Apri
Pubblicazioni consigliate

Aisberg ©2008 Servizi bibliotecari, Università degli studi di Bergamo | Terms of use/Condizioni di utilizzo

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10446/112209
Citazioni
  • Scopus 22
  • ???jsp.display-item.citation.isi??? 18
social impact