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
Added the option '-subDict' to specify a sub-dictionary if multiple
replacement sets are present in the same file. This also provides
backward compatibility by setting '-subDict dictionaryReplacement'
In most boundary conditions, fvOptions etc. required and optional fields
to be looked-up from the objectRegistry are selected by setting the
keyword corresponding to the standard field name in the BC etc. to the
appropriate name in the objectRegistry. Usually a default is provided
with sets the field name to the keyword name, e.g. in the
totalPressureFvPatchScalarField the velocity is selected by setting the
keyword 'U' to the appropriate name which defaults to 'U':
Property | Description | Required | Default value
U | velocity field name | no | U
phi | flux field name | no | phi
.
.
.
However, in some BCs and functionObjects and many fvOptions another
convention is used in which the field name keyword is appended by 'Name'
e.g.
Property | Description | Required | Default value
pName | pressure field name | no | p
UName | velocity field name | no | U
This difference in convention is unnecessary and confusing, hinders code
and dictionary reuse and complicates code maintenance. In this commit
the appended 'Name' is removed from the field selection keywords
standardizing OpenFOAM on the first convention above.
Also added the new prghTotalHydrostaticPressure p_rgh BC which uses the
hydrostatic pressure field as the reference state for the far-field
which provides much more accurate entrainment is large open domains
typical of many fire simulations.
The hydrostatic field solution is controlled by the optional entries in
the fvSolution.PIMPLE dictionary, e.g.
hydrostaticInitialization yes;
nHydrostaticCorrectors 5;
and the solver must also be specified for the hydrostatic p_rgh field
ph_rgh e.g.
ph_rgh
{
$p_rgh;
}
Suitable boundary conditions for ph_rgh cannot always be derived from
those for p_rgh and so the ph_rgh is read to provide them.
To avoid accuracy issues with IO, restart and post-processing the p_rgh
and ph_rgh the option to specify a suitable reference pressure is
provided via the optional pRef file in the constant directory, e.g.
dimensions [1 -1 -2 0 0 0 0];
value 101325;
which is used in the relationship between p_rgh and p:
p = p_rgh + rho*gh + pRef;
Note that if pRef is specified all pressure BC specifications in the
p_rgh and ph_rgh files are relative to the reference to avoid round-off
errors.
For examples of suitable BCs for p_rgh and ph_rgh for a range of
fireFoam cases please study the tutorials in
tutorials/combustion/fireFoam/les which have all been updated.
Henry G. Weller
CFD Direct Ltd.
in decomposeParDict.
This default number of processors may be overridden by the new "-np"
option to runParallel which must be specified before the application
name e.g.:
runParallel -np 4 pisoFoam
Adding boundary file from our dev to incompressible/simpleFoam/airFoil2D
Adding missing boundaryRadiationProperties combustion/fireFoam/les/flameSpreadWaterSuppressionPanel
