Commit Graph

4 Commits

Author SHA1 Message Date
Andrew Heather
3dbd39146c STYLE: consistency updates 2016-09-27 15:17:55 +01:00
Andrew Heather
9fbd612672 GIT: Initial state after latest Foundation merge 2016-09-20 14:49:08 +01:00
Henry Weller
0857f479a8 PBiCGStab: New preconditioned bi-conjugate gradient stabilized solver for asymmetric lduMatrices
using a run-time selectable preconditioner

References:
    Van der Vorst, H. A. (1992).
    Bi-CGSTAB: A fast and smoothly converging variant of Bi-CG
    for the solution of nonsymmetric linear systems.
    SIAM Journal on scientific and Statistical Computing, 13(2), 631-644.

    Barrett, R., Berry, M. W., Chan, T. F., Demmel, J., Donato, J.,
    Dongarra, J., Eijkhout, V., Pozo, R., Romine, C. & Van der Vorst, H.
    (1994).
    Templates for the solution of linear systems:
    building blocks for iterative methods
    (Vol. 43). Siam.

See also: https://en.wikipedia.org/wiki/Biconjugate_gradient_stabilized_method

Tests have shown that PBiCGStab with the DILU preconditioner is more
robust, reliable and shows faster convergence (~2x) than PBiCG with
DILU, in particular in parallel where PBiCG occasionally diverges.

This remarkable improvement over PBiCG prompted the update of all
tutorial cases currently using PBiCG to use PBiCGStab instead.  If any
issues arise with this update please report on Mantis: http://bugs.openfoam.org
2016-09-05 11:46:42 +01:00
Henry Weller
1d57269680 TDACChemistryModel: New chemistry model providing Tabulation of Dynamic Adaptive Chemistry
Provides efficient integration of complex laminar reaction chemistry,
combining the advantages of automatic dynamic specie and reaction
reduction with ISAT (in situ adaptive tabulation).  The advantages grow
as the complexity of the chemistry increases.

References:
    Contino, F., Jeanmart, H., Lucchini, T., & D’Errico, G. (2011).
    Coupling of in situ adaptive tabulation and dynamic adaptive chemistry:
    An effective method for solving combustion in engine simulations.
    Proceedings of the Combustion Institute, 33(2), 3057-3064.

    Contino, F., Lucchini, T., D'Errico, G., Duynslaegher, C.,
    Dias, V., & Jeanmart, H. (2012).
    Simulations of advanced combustion modes using detailed chemistry
    combined with tabulation and mechanism reduction techniques.
    SAE International Journal of Engines,
    5(2012-01-0145), 185-196.

    Contino, F., Foucher, F., Dagaut, P., Lucchini, T., D’Errico, G., &
    Mounaïm-Rousselle, C. (2013).
    Experimental and numerical analysis of nitric oxide effect on the
    ignition of iso-octane in a single cylinder HCCI engine.
    Combustion and Flame, 160(8), 1476-1483.

    Contino, F., Masurier, J. B., Foucher, F., Lucchini, T., D’Errico, G., &
    Dagaut, P. (2014).
    CFD simulations using the TDAC method to model iso-octane combustion
    for a large range of ozone seeding and temperature conditions
    in a single cylinder HCCI engine.
    Fuel, 137, 179-184.

Two tutorial cases are currently provided:
    + tutorials/combustion/chemFoam/ic8h18_TDAC
    + tutorials/combustion/reactingFoam/laminar/counterFlowFlame2D_GRI_TDAC

the first of which clearly demonstrates the advantage of dynamic
adaptive chemistry providing ~10x speedup,

the second demonstrates ISAT on the modest complex GRI mechanisms for
methane combustion, providing a speedup of ~4x.

More tutorials demonstrating TDAC on more complex mechanisms and cases
will be provided soon in addition to documentation for the operation and
settings of TDAC.  Also further updates to the TDAC code to improve
consistency and integration with the rest of OpenFOAM and further
optimize operation can be expected.

Original code providing all algorithms for chemistry reduction and
tabulation contributed by Francesco Contino, Tommaso Lucchini, Gianluca
D’Errico, Hervé Jeanmart, Nicolas Bourgeois and Stéphane Backaert.

Implementation updated, optimized and integrated into OpenFOAM-dev by
Henry G. Weller, CFD Direct Ltd with the help of Francesco Contino.
2016-07-17 15:13:54 +01:00