splitMeshRegions.C

/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     |
    \\  /    A nd           | Copyright (C) 1991-2009 OpenCFD Ltd.
     \\/     M anipulation  |
-------------------------------------------------------------------------------
License
    This file is part of OpenFOAM.

    OpenFOAM is free software; you can redistribute it and/or modify it
    under the terms of the GNU General Public License as published by the
    Free Software Foundation; either version 2 of the License, or (at your
    option) any later version.

    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    for more details.

    You should have received a copy of the GNU General Public License
    along with OpenFOAM; if not, write to the Free Software Foundation,
    Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA

Description
    Splits mesh into multiple regions. Each region is defined as a domain
    whose cells can all be reached by cell-face-cell walking without crossing
    - boundary faces
    - additional faces from faceset (-blockedFaces faceSet).
    - any face inbetween differing cellZones (-cellZones)

    Output is:
    - mesh with multiple regions
    - mesh with cells put into cellZones (-makeCellZones)

    Should work in parallel but cellZone interfaces cannot align with
    processor boundaries so use the correct option in decomposition to
    preserve those interfaces.

\*---------------------------------------------------------------------------*/

#include "SortableList.H"
#include "argList.H"
#include "regionSplit.H"
#include "fvMeshSubset.H"
#include "IOobjectList.H"
#include "volFields.H"
#include "faceSet.H"
#include "cellSet.H"
#include "polyTopoChange.H"
#include "removeCells.H"
#include "EdgeMap.H"
#include "syncTools.H"
#include "ReadFields.H"

using namespace Foam;

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

template<class GeoField>
void addPatchFields(fvMesh& mesh, const word& patchFieldType)
{
    HashTable<const GeoField*> flds
    (
        mesh.objectRegistry::lookupClass<GeoField>()
    );

    for
    (
        typename HashTable<const GeoField*>::const_iterator iter = flds.begin();
        iter != flds.end();
        ++iter
    )
    {
        const GeoField& fld = *iter();

        typename GeoField::GeometricBoundaryField& bfld =
            const_cast<typename GeoField::GeometricBoundaryField&>
            (
                fld.boundaryField()
            );

        label sz = bfld.size();
        bfld.setSize(sz+1);
        bfld.set
        (
            sz,
            GeoField::PatchFieldType::New
            (
                patchFieldType,
                mesh.boundary()[sz],
                fld.dimensionedInternalField()
            )
        );
    }
}


// Remove last patch field
template<class GeoField>
void trimPatchFields(fvMesh& mesh, const label nPatches)
{
    HashTable<const GeoField*> flds
    (
        mesh.objectRegistry::lookupClass<GeoField>()
    );

    for
    (
        typename HashTable<const GeoField*>::const_iterator iter = flds.begin();
        iter != flds.end();
        ++iter
    )
    {
        const GeoField& fld = *iter();

        const_cast<typename GeoField::GeometricBoundaryField&>
        (
            fld.boundaryField()
        ).setSize(nPatches);
    }
}


// Reorder patch field
template<class GeoField>
void reorderPatchFields(fvMesh& mesh, const labelList& oldToNew)
{
    HashTable<const GeoField*> flds
    (
        mesh.objectRegistry::lookupClass<GeoField>()
    );

    for
    (
        typename HashTable<const GeoField*>::const_iterator iter = flds.begin();
        iter != flds.end();
        ++iter
    )
    {
        const GeoField& fld = *iter();

        typename GeoField::GeometricBoundaryField& bfld =
            const_cast<typename GeoField::GeometricBoundaryField&>
            (
                fld.boundaryField()
            );

        bfld.reorder(oldToNew);
    }
}


// Adds patch if not yet there. Returns patchID.
label addPatch
(
    fvMesh& mesh,
    const word& patchName,
    const word& patchType
)
{
    polyBoundaryMesh& polyPatches =
        const_cast<polyBoundaryMesh&>(mesh.boundaryMesh());

    label patchI = polyPatches.findPatchID(patchName);
    if (patchI != -1)
    {
        if (polyPatches[patchI].type() == patchType)
        {
            // Already there
            return patchI;
        }
    }


    label insertPatchI = polyPatches.size();
    label startFaceI = mesh.nFaces();

    forAll(polyPatches, patchI)
    {
        const polyPatch& pp = polyPatches[patchI];

        if (isA<processorPolyPatch>(pp))
        {
            insertPatchI = patchI;
            startFaceI = pp.start();
            break;
        }
    }


    // Below is all quite a hack. Feel free to change once there is a better
    // mechanism to insert and reorder patches.

    // Clear local fields and e.g. polyMesh parallelInfo.
    mesh.clearOut();

    label sz = polyPatches.size();

    fvBoundaryMesh& fvPatches = const_cast<fvBoundaryMesh&>(mesh.boundary());

    // Add polyPatch at the end
    polyPatches.setSize(sz+1);
    polyPatches.set
    (
        sz,
        polyPatch::New
        (
            patchType,
            patchName,
            0,              // size
            startFaceI,
            insertPatchI,
            polyPatches
        )
    );
    fvPatches.setSize(sz+1);
    fvPatches.set
    (
        sz,
        fvPatch::New
        (
            polyPatches[sz],  // point to newly added polyPatch
            mesh.boundary()
        )
    );

    addPatchFields<volScalarField>
    (
        mesh,
        calculatedFvPatchField<scalar>::typeName
    );
    addPatchFields<volVectorField>
    (
        mesh,
        calculatedFvPatchField<vector>::typeName
    );
    addPatchFields<volSphericalTensorField>
    (
        mesh,
        calculatedFvPatchField<sphericalTensor>::typeName
    );
    addPatchFields<volSymmTensorField>
    (
        mesh,
        calculatedFvPatchField<symmTensor>::typeName
    );
    addPatchFields<volTensorField>
    (
        mesh,
        calculatedFvPatchField<tensor>::typeName
    );

    // Surface fields

    addPatchFields<surfaceScalarField>
    (
        mesh,
        calculatedFvPatchField<scalar>::typeName
    );
    addPatchFields<surfaceVectorField>
    (
        mesh,
        calculatedFvPatchField<vector>::typeName
    );
    addPatchFields<surfaceSphericalTensorField>
    (
        mesh,
        calculatedFvPatchField<sphericalTensor>::typeName
    );
    addPatchFields<surfaceSymmTensorField>
    (
        mesh,
        calculatedFvPatchField<symmTensor>::typeName
    );
    addPatchFields<surfaceTensorField>
    (
        mesh,
        calculatedFvPatchField<tensor>::typeName
    );

    // Create reordering list
    // patches before insert position stay as is
    labelList oldToNew(sz+1);
    for (label i = 0; i < insertPatchI; i++)
    {
        oldToNew[i] = i;
    }
    // patches after insert position move one up
    for (label i = insertPatchI; i < sz; i++)
    {
        oldToNew[i] = i+1;
    }
    // appended patch gets moved to insert position
    oldToNew[sz] = insertPatchI;

    // Shuffle into place
    polyPatches.reorder(oldToNew);
    fvPatches.reorder(oldToNew);

    reorderPatchFields<volScalarField>(mesh, oldToNew);
    reorderPatchFields<volVectorField>(mesh, oldToNew);
    reorderPatchFields<volSphericalTensorField>(mesh, oldToNew);
    reorderPatchFields<volSymmTensorField>(mesh, oldToNew);
    reorderPatchFields<volTensorField>(mesh, oldToNew);
    reorderPatchFields<surfaceScalarField>(mesh, oldToNew);
    reorderPatchFields<surfaceVectorField>(mesh, oldToNew);
    reorderPatchFields<surfaceSphericalTensorField>(mesh, oldToNew);
    reorderPatchFields<surfaceSymmTensorField>(mesh, oldToNew);
    reorderPatchFields<surfaceTensorField>(mesh, oldToNew);

    return insertPatchI;
}


// Reorder and delete patches.
void reorderPatches
(
    fvMesh& mesh,
    const labelList& oldToNew,
    const label nNewPatches
)
{
    polyBoundaryMesh& polyPatches =
        const_cast<polyBoundaryMesh&>(mesh.boundaryMesh());
    fvBoundaryMesh& fvPatches = const_cast<fvBoundaryMesh&>(mesh.boundary());

    // Shuffle into place
    polyPatches.reorder(oldToNew);
    fvPatches.reorder(oldToNew);

    reorderPatchFields<volScalarField>(mesh, oldToNew);
    reorderPatchFields<volVectorField>(mesh, oldToNew);
    reorderPatchFields<volSphericalTensorField>(mesh, oldToNew);
    reorderPatchFields<volSymmTensorField>(mesh, oldToNew);
    reorderPatchFields<volTensorField>(mesh, oldToNew);
    reorderPatchFields<surfaceScalarField>(mesh, oldToNew);
    reorderPatchFields<surfaceVectorField>(mesh, oldToNew);
    reorderPatchFields<surfaceSphericalTensorField>(mesh, oldToNew);
    reorderPatchFields<surfaceSymmTensorField>(mesh, oldToNew);
    reorderPatchFields<surfaceTensorField>(mesh, oldToNew);

    // Remove last.
    polyPatches.setSize(nNewPatches);
    fvPatches.setSize(nNewPatches);
    trimPatchFields<volScalarField>(mesh, nNewPatches);
    trimPatchFields<volVectorField>(mesh, nNewPatches);
    trimPatchFields<volSphericalTensorField>(mesh, nNewPatches);
    trimPatchFields<volSymmTensorField>(mesh, nNewPatches);
    trimPatchFields<volTensorField>(mesh, nNewPatches);
    trimPatchFields<surfaceScalarField>(mesh, nNewPatches);
    trimPatchFields<surfaceVectorField>(mesh, nNewPatches);
    trimPatchFields<surfaceSphericalTensorField>(mesh, nNewPatches);
    trimPatchFields<surfaceSymmTensorField>(mesh, nNewPatches);
    trimPatchFields<surfaceTensorField>(mesh, nNewPatches);
}


template<class GeoField>
void subsetVolFields
(
    const fvMesh& mesh,
    const fvMesh& subMesh,
    const labelList& cellMap,
    const labelList& faceMap
)
{
    const labelList patchMap(identity(mesh.boundaryMesh().size()));

    HashTable<const GeoField*> fields
    (
        mesh.objectRegistry::lookupClass<GeoField>()
    );
    forAllConstIter(typename HashTable<const GeoField*>, fields, iter)
    {
        const GeoField& fld = *iter();

        Info<< "Mapping field " << fld.name() << endl;

        tmp<GeoField> tSubFld
        (
            fvMeshSubset::interpolate
            (
                fld,
                subMesh,
                patchMap,
                cellMap,
                faceMap
            )
        );

        // Hack: set value to 0 for introduced patches (since don't
        //       get initialised.
        forAll(tSubFld().boundaryField(), patchI)
        {
            const fvPatchField<typename GeoField::value_type>& pfld =
                tSubFld().boundaryField()[patchI];

            if
            (
                isA<calculatedFvPatchField<typename GeoField::value_type> >
                (pfld)
            )
            {
                tSubFld().boundaryField()[patchI] ==
                    pTraits<typename GeoField::value_type>::zero;
            }
        }

        // Store on subMesh
        GeoField* subFld = tSubFld.ptr();
        subFld->rename(fld.name());
        subFld->writeOpt() = IOobject::AUTO_WRITE;
        subFld->store();
    }
}


template<class GeoField>
void subsetSurfaceFields
(
    const fvMesh& mesh,
    const fvMesh& subMesh,
    const labelList& faceMap
)
{
    const labelList patchMap(identity(mesh.boundaryMesh().size()));

    HashTable<const GeoField*> fields
    (
        mesh.objectRegistry::lookupClass<GeoField>()
    );
    forAllConstIter(typename HashTable<const GeoField*>, fields, iter)
    {
        const GeoField& fld = *iter();

        Info<< "Mapping field " << fld.name() << endl;

        tmp<GeoField> tSubFld
        (
            fvMeshSubset::interpolate
            (
                fld,
                subMesh,
                patchMap,
                faceMap
            )
        );

        // Hack: set value to 0 for introduced patches (since don't
        //       get initialised.
        forAll(tSubFld().boundaryField(), patchI)
        {
            const fvsPatchField<typename GeoField::value_type>& pfld =
                tSubFld().boundaryField()[patchI];

            if
            (
                isA<calculatedFvsPatchField<typename GeoField::value_type> >
                (pfld)
            )
            {
                tSubFld().boundaryField()[patchI] ==
                    pTraits<typename GeoField::value_type>::zero;
            }
        }

        // Store on subMesh
        GeoField* subFld = tSubFld.ptr();
        subFld->rename(fld.name());
        subFld->writeOpt() = IOobject::AUTO_WRITE;
        subFld->store();
    }
}

// Select all cells not in the region
labelList getNonRegionCells(const labelList& cellRegion, const label regionI)
{
    DynamicList<label> nonRegionCells(cellRegion.size());
    forAll(cellRegion, cellI)
    {
        if (cellRegion[cellI] != regionI)
        {
            nonRegionCells.append(cellI);
        }
    }
    return nonRegionCells.shrink();
}


// Get per region-region interface the sizes.
// If sumParallel does merge.
EdgeMap<label> getInterfaceSizes
(
    const polyMesh& mesh,
    const labelList& cellRegion,
    const bool sumParallel
)
{
    EdgeMap<label> interfaceSizes;

    forAll(mesh.faceNeighbour(), faceI)
    {
        label ownRegion = cellRegion[mesh.faceOwner()[faceI]];
        label neiRegion = cellRegion[mesh.faceNeighbour()[faceI]];

        if (ownRegion != neiRegion)
        {
            edge interface
            (
                min(ownRegion, neiRegion),
                max(ownRegion, neiRegion)
            );

            EdgeMap<label>::iterator iter = interfaceSizes.find(interface);

            if (iter != interfaceSizes.end())
            {
                iter()++;
            }
            else
            {
                interfaceSizes.insert(interface, 1);
            }
        }
    }

    if (sumParallel && Pstream::parRun())
    {
        if (Pstream::master())
        {
            // Receive and add to my sizes
            for
            (
                int slave=Pstream::firstSlave();
                slave<=Pstream::lastSlave();
                slave++
            )
            {
                IPstream fromSlave(Pstream::blocking, slave);

                EdgeMap<label> slaveSizes(fromSlave);

                forAllConstIter(EdgeMap<label>, slaveSizes, slaveIter)
                {
                    EdgeMap<label>::iterator masterIter =
                        interfaceSizes.find(slaveIter.key());

                    if (masterIter != interfaceSizes.end())
                    {
                        masterIter() += slaveIter();
                    }
                    else
                    {
                        interfaceSizes.insert(slaveIter.key(), slaveIter());
                    }
                }
            }

            // Distribute
            for
            (
                int slave=Pstream::firstSlave();
                slave<=Pstream::lastSlave();
                slave++
            )
            {
                // Receive the edges using shared points from the slave.
                OPstream toSlave(Pstream::blocking, slave);
                toSlave << interfaceSizes;
            }
        }
        else
        {
            // Send to master
            {
                OPstream toMaster(Pstream::blocking, Pstream::master());
                toMaster << interfaceSizes;
            }
            // Receive from master
            {
                IPstream fromMaster(Pstream::blocking, Pstream::master());
                fromMaster >> interfaceSizes;
            }
        }
    }

    return interfaceSizes;
}


// Create mesh for region.
autoPtr<mapPolyMesh> createRegionMesh
(
    const regionSplit& cellRegion,
    const EdgeMap<label>& interfaceToPatch,
    const fvMesh& mesh,
    const label regionI,
    const word& regionName,
    autoPtr<fvMesh>& newMesh
)
{
    // Create dummy system/fv*
    {
        IOobject io
        (
            "fvSchemes",
            mesh.time().system(),
            regionName,
            mesh.db(),
            IOobject::NO_READ,
            IOobject::NO_WRITE,
            false
        );

        Info<< "Testing:" << io.objectPath() << endl;

        if (!io.headerOk())
        //if (!exists(io.objectPath()))
        {
            Info<< "Writing dummy " << regionName/io.name() << endl;
            dictionary dummyDict;
            dictionary divDict;
            dummyDict.add("divSchemes", divDict);
            dictionary gradDict;
            dummyDict.add("gradSchemes", gradDict);
            dictionary laplDict;
            dummyDict.add("laplacianSchemes", laplDict);

            IOdictionary(io, dummyDict).regIOobject::write();
        }
    }
    {
        IOobject io
        (
            "fvSolution",
            mesh.time().system(),
            regionName,
            mesh.db(),
            IOobject::NO_READ,
            IOobject::NO_WRITE,
            false
        );

        if (!io.headerOk())
        //if (!exists(io.objectPath()))
        {
            Info<< "Writing dummy " << regionName/io.name() << endl;
            dictionary dummyDict;
            IOdictionary(io, dummyDict).regIOobject::write();
        }
    }


    // Topology change container. Start off from existing mesh.
    polyTopoChange meshMod(mesh);

    // Cell remover engine
    removeCells cellRemover(mesh);

    // Select all but region cells
    labelList cellsToRemove(getNonRegionCells(cellRegion, regionI));

    // Find out which faces will get exposed. Note that this
    // gets faces in mesh face order. So both regions will get same
    // face in same order (important!)
    labelList exposedFaces = cellRemover.getExposedFaces(cellsToRemove);

    labelList exposedPatchIDs(exposedFaces.size());
    forAll(exposedFaces, i)
    {
        label faceI = exposedFaces[i];

        if (!mesh.isInternalFace(faceI))
        {
            FatalErrorIn("createRegionMesh(..)")
                << "Exposed face:" << faceI << " is not an internal face."
                << " fc:" << mesh.faceCentres()[faceI]
                << exit(FatalError);
        }

        label ownRegion = cellRegion[mesh.faceOwner()[faceI]];
        label neiRegion = cellRegion[mesh.faceNeighbour()[faceI]];

        label otherRegion = -1;

        if (ownRegion == regionI && neiRegion != regionI)
        {
            otherRegion = neiRegion;
        }
        else if (ownRegion != regionI && neiRegion == regionI)
        {
            otherRegion = ownRegion;
        }
        else
        {
            FatalErrorIn("createRegionMesh(..)")
                << "Exposed face:" << faceI
                << " fc:" << mesh.faceCentres()[faceI]
                << " has owner region " << ownRegion
                << " and neighbour region " << neiRegion
                << " when handling region:" << regionI
                << exit(FatalError);
        }

        if (otherRegion != -1)
        {
            edge interface
            (
                min(regionI, otherRegion),
                max(regionI, otherRegion)
            );

            // Find the patch.
            if (regionI < otherRegion)
            {
                exposedPatchIDs[i] = interfaceToPatch[interface];
            }
            else
            {
                exposedPatchIDs[i] = interfaceToPatch[interface]+1;
            }
        }
    }

    // Remove faces
    cellRemover.setRefinement
    (
        cellsToRemove,
        exposedFaces,
        exposedPatchIDs,
        meshMod
    );

    autoPtr<mapPolyMesh> map = meshMod.makeMesh
    (
        newMesh,
        IOobject
        (
            regionName,
            mesh.time().timeName(),
            mesh.time(),
            IOobject::NO_READ,
            IOobject::AUTO_WRITE
        ),
        mesh
    );

    return map;
}


void createAndWriteRegion
(
    const fvMesh& mesh,
    const regionSplit& cellRegion,
    const wordList& regionNames,
    const EdgeMap<label>& interfaceToPatch,
    const label regionI
)
{
    Info<< "Creating mesh for region " << regionI
        << ' ' << regionNames[regionI] << endl;

    autoPtr<fvMesh> newMesh;
    autoPtr<mapPolyMesh> map = createRegionMesh
    (
        cellRegion,
        interfaceToPatch,
        mesh,
        regionI,
        regionNames[regionI],
        newMesh
    );

    Info<< "Mapping fields" << endl;

    // Map existing fields
    newMesh().updateMesh(map());

    // Add subsetted fields
    subsetVolFields<volScalarField>
    (
        mesh,
        newMesh(),
        map().cellMap(),
        map().faceMap()
    );
    subsetVolFields<volVectorField>
    (
        mesh,
        newMesh(),
        map().cellMap(),
        map().faceMap()
    );
    subsetVolFields<volSphericalTensorField>
    (
        mesh,
        newMesh(),
        map().cellMap(),
        map().faceMap()
    );
    subsetVolFields<volSymmTensorField>
    (
        mesh,
        newMesh(),
        map().cellMap(),
        map().faceMap()
    );
    subsetVolFields<volTensorField>
    (
        mesh,
        newMesh(),
        map().cellMap(),
        map().faceMap()
    );

    subsetSurfaceFields<surfaceScalarField>
    (
        mesh,
        newMesh(),
        map().faceMap()
    );
    subsetSurfaceFields<surfaceVectorField>
    (
        mesh,
        newMesh(),
        map().faceMap()
    );
    subsetSurfaceFields<surfaceSphericalTensorField>
    (
        mesh,
        newMesh(),
        map().faceMap()
    );
    subsetSurfaceFields<surfaceSymmTensorField>
    (
        mesh,
        newMesh(),
        map().faceMap()
    );
    subsetSurfaceFields<surfaceTensorField>
    (
        mesh,
        newMesh(),
        map().faceMap()
    );


    const polyBoundaryMesh& newPatches = newMesh().boundaryMesh();

    // Delete empty patches
    // ~~~~~~~~~~~~~~~~~~~~

    // Create reordering list to move patches-to-be-deleted to end
    labelList oldToNew(newPatches.size(), -1);
    label newI = 0;

    Info<< "Deleting empty patches" << endl;

    // Assumes all non-proc boundaries are on all processors!
    forAll(newPatches, patchI)
    {
        const polyPatch& pp = newPatches[patchI];

        if
        (
            !isA<processorPolyPatch>(pp)
         && returnReduce(pp.size(), sumOp<label>()) > 0
        )
        {
            oldToNew[patchI] = newI++;
        }
    }

    // Same for processor patches (but need no reduction)
    forAll(newPatches, patchI)
    {
        const polyPatch& pp = newPatches[patchI];

        if (isA<processorPolyPatch>(pp) && pp.size() > 0)
        {
            oldToNew[patchI] = newI++;
        }
    }

    const label nNewPatches = newI;

    // Move all deleteable patches to the end
    forAll(oldToNew, patchI)
    {
        if (oldToNew[patchI] == -1)
        {
            oldToNew[patchI] = newI++;
        }
    }

    reorderPatches(newMesh(), oldToNew, nNewPatches);


    Info<< "Writing new mesh" << endl;

    newMesh().write();

    // Write addressing files like decomposePar
    Info<< "Writing addressing to base mesh" << endl;

    labelIOList pointProcAddressing
    (
        IOobject
        (
            "pointRegionAddressing",
            newMesh().facesInstance(),
            newMesh().meshSubDir,
            newMesh(),
            IOobject::NO_READ,
            IOobject::NO_WRITE,
            false
        ),
        map().pointMap()
    );
    Info<< "Writing map " << pointProcAddressing.name()
        << " from region" << regionI
        << " points back to base mesh." << endl;
    pointProcAddressing.write();

    labelIOList faceProcAddressing
    (
        IOobject
        (
            "faceRegionAddressing",
            newMesh().facesInstance(),
            newMesh().meshSubDir,
            newMesh(),
            IOobject::NO_READ,
            IOobject::NO_WRITE,
            false
        ),
        newMesh().nFaces()
    );
    forAll(faceProcAddressing, faceI)
    {
        // face + turning index. (see decomposePar)
        // Is the face pointing in the same direction?
        label oldFaceI = map().faceMap()[faceI];

        if
        (
            map().cellMap()[newMesh().faceOwner()[faceI]]
         == mesh.faceOwner()[oldFaceI]
        )
        {
            faceProcAddressing[faceI] = oldFaceI+1;
        }
        else
        {
            faceProcAddressing[faceI] = -(oldFaceI+1);
        }
    }
    Info<< "Writing map " << faceProcAddressing.name()
        << " from region" << regionI
        << " faces back to base mesh." << endl;
    faceProcAddressing.write();

    labelIOList cellProcAddressing
    (
        IOobject
        (
            "cellRegionAddressing",
            newMesh().facesInstance(),
            newMesh().meshSubDir,
            newMesh(),
            IOobject::NO_READ,
            IOobject::NO_WRITE,
            false
        ),
        map().cellMap()
    );
    Info<< "Writing map " <<cellProcAddressing.name()
        << " from region" << regionI
        << " cells back to base mesh." << endl;
    cellProcAddressing.write();
}


EdgeMap<label> addRegionPatches
(
    fvMesh& mesh,
    const regionSplit& cellRegion,
    const EdgeMap<label>& interfaceSizes,
    const wordList& regionNames
)
{
    // Check that all patches are present in same order.
    mesh.boundaryMesh().checkParallelSync(true);

    Info<< nl << "Adding patches" << nl << endl;

    EdgeMap<label> interfaceToPatch(cellRegion.nRegions());