This is a map data structure rather than a class or function which performs the
mapping operation so polyMeshDistributionMap is more logical and comprehensible
than mapDistributePolyMesh.
When snappyHexMesh is run in parallel it re-balances the mesh during refinement
and layer addition by redistribution which requires a decomposition method
that operates in parallel, e.g. hierachical or ptscotch. decomposePar uses a
decomposition method which operates in serial e.g. hierachical but NOT
ptscotch. In order to run decomposePar followed by snappyHexMesh in parallel it
has been necessary to change the method specified in decomposeParDict but now
this is avoided by separately specifying the decomposition and distribution
methods, e.g. in the incompressible/simpleFoam/motorBike case:
numberOfSubdomains 6;
decomposer hierarchical;
distributor ptscotch;
hierarchicalCoeffs
{
n (3 2 1);
order xyz;
}
The distributor entry is also used for run-time mesh redistribution, e.g. in the
multiphase/interFoam/RAS/floatingObject case re-distribution for load-balancing
is enabled in constant/dynamicMeshDict:
distributor
{
type distributor;
libs ("libfvMeshDistributors.so");
redistributionInterval 10;
}
which uses the distributor specified in system/decomposeParDict:
distributor hierarchical;
This rationalisation provides the structure for development of mesh
redistribution and load-balancing.
Geometric point merging has an inherent chance of failure that occurs
when a mesh contains valid distinct points that are closer together than
the supplied tolerance. It is beneficial to avoid such merging whenever
possible.
reconstructParMesh does not need explicit point merging any more. Points
may be duplicated temporarily when processor meshes are combined which
share points and edges but not faces. Ultimately, however,
reconstructParMesh reconstructs the entire mesh so everything eventually
gets face-connected and all point duplications get resolved.
fvMeshDistribute requires point-merging, as the entire mesh is not
constructed. However, since 5d4c8f5d, this process has been purely
topological and has not relied on any of the geometric merging processes
triggered by utilised code.
As such, all geometric point merging operations and tolerances have been
removed from these two implementations, as well as in lower level code
in faceCoupleInfo and polyMeshAdder. faceCoupleInfo has also had support
for face and edge splits removed as this was not being used. This change
will have improved the robustness of both reconstruction and
redistributuon and has greatly reduced the total amount of code
involved.
The only geometric tolerance-based matching still being performed by
either of these processes is as a result of coupled patch ordering in
fvMeshDistribute. It is possible that this is not necessary either
(though at present coupled patch ordering is certainly needed
elsewhere). This warrants further investigation.
splitMeshRegions: handle flipping of faces for surface fields
subsetMesh: subset dimensionedFields
decomposePar: use run-time selection of decomposition constraints. Used to
keep cells on particular processors. See the decomposeParDict in
$FOAM_UTILITIES/parallel/decomposePar:
- preserveBaffles: keep baffle faces on same processor
- preserveFaceZones: keep faceZones owner and neighbour on same processor
- preservePatches: keep owner and neighbour on same processor. Note: not
suitable for cyclicAMI since these are not coupled on the patch level
- singleProcessorFaceSets: keep complete faceSet on a single processor
- refinementHistory: keep cells originating from a single cell on the
same processor.
decomposePar: clean up decomposition of refinement data from snappyHexMesh
reconstructPar: reconstruct refinement data (refineHexMesh, snappyHexMesh)
reconstructParMesh: reconstruct refinement data (refineHexMesh, snappyHexMesh)
redistributePar:
- corrected mapping surfaceFields
- adding processor patches in order consistent with decomposePar
argList: check that slaves are running same version as master
fvMeshSubset: move to dynamicMesh library
fvMeshDistribute:
- support for mapping dimensionedFields
- corrected mapping of surfaceFields
parallel routines: allow parallel running on single processor
Field: support for
- distributed mapping
- mapping with flipping
mapDistribute: support for flipping
AMIInterpolation: avoid constructing localPoints
To be used instead of zeroGradientFvPatchField for temporary fields for
which zero-gradient extrapolation is use to evaluate the boundary field
but avoiding fields derived from temporary field using field algebra
inheriting the zeroGradient boundary condition by the reuse of the
temporary field storage.
zeroGradientFvPatchField should not be used as the default patch field
for any temporary fields and should be avoided for non-temporary fields
except where it is clearly appropriate;
extrapolatedCalculatedFvPatchField and calculatedFvPatchField are
generally more suitable defaults depending on the manner in which the
boundary values are specified or evaluated.
The entire OpenFOAM-dev code-base has been updated following the above
recommendations.
Henry G. Weller
CFD Direct
