Preconditioner freezing for ContField::GlobalSolve

Henrik Wustenbergrequested to merge
hwustenb/nektar:feature/vcsimplicit-precon-freeze into master

Issue/feature addressed

Time-dependent matrix system require re-building of local matrices at every time step. This also requires re-building the preconditioner which is computationally expensive. In particular, for the IncNavierStokesSolver with VCSImplicit.

Proposed solution

Separate initialising the GlobalLinearSystem (matrix) and the preconditioner, and add the possibility to hold a reference to the preconditioner in ContField.

Implementation

Added a function InitPreconditioner in GlobalSolve which builds the preconditioner. Additionally, the ContField holds a reference to the preconditioner via shared_ptr. InitPreconditioner additionally checks whether a non-Null preconditioner ptr is available.

Tests

  • All previous iterative tests with VCSImplicit that use a Block or LowEnergyBlock preconditioner.
  • For example Tet_Kovasnay_PreconditionerBlock.xml and Tet_Kovasnay_PreconditionerLowEnergyBlock.xml
  • Added a test for IterativeFull Tet_Kovasnay_VCSImplicit.xml

Suggested reviewers

@CFD-Xing

Notes

Checklist

  • Functions and classes, or changes to them, are documented.
  • User guide/documentation is updated.
  • Changelog is updated.
  • Suitable tests added for new functionality.
  • Contributed code is correctly formatted. (See the contributing guidelines).
  • License added to any new files.
  • No extraneous files have been added (e.g. compiler output or test data files).
Edited by Henrik Wustenberg

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