Augmented Lagrangian-based preconditioners for steady buoyancy driven flow

G. Ke, E. Aulisa, G. Dillon, V. Howle

Research output: Contribution to journalArticle

1 Scopus citations

Abstract

In this paper, we apply the augmented Lagrangian (AL) approach to steady buoyancy driven flow problems. Two AL preconditioners are developed based on the variable's order, specifically whether the leading variable is the velocity or the temperature variable. Correspondingly, two non-augmented Lagrangian (NAL) preconditioners are also considered for comparison. An eigenvalue analysis for these two pairs of preconditioners is conducted to predict the rate of convergence for the GMRES solver. The numerical results show that the AL preconditioner pair is insensitive with respect to the mesh size, Rayleigh number, and Prandtl number in terms of GMRES iterations, resulting in a significantly more robust preconditioner pair compared to the NAL pair. Accordingly, the AL pair performs much better than the NAL pair in terms of computational time. For the AL pair, the preconditioner with velocity as the leading variable gives slightly better efficiency than the one with temperature as the leading variable.

Original languageEnglish
Pages (from-to)1-7
Number of pages7
JournalApplied Mathematics Letters
Volume82
DOIs
StatePublished - Aug 2018

Keywords

  • Augmented Lagrangian preconditioners
  • Buoyancy driven flow problems
  • Eigenvalue analysis
  • Finite element method

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