From 14934a9bfc52cc3b918f77fab9ed2178bcfbf2e3 Mon Sep 17 00:00:00 2001
From: mattijs <mattijs>
Date: Tue, 14 May 2013 16:45:59 +0100
Subject: [PATCH 1/5] BUG: faceAreaPairGAMGAgglomeration: corrected face area
 -> weight conversion

---
 .../faceAreaPairGAMGAgglomeration.C                          | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/src/finiteVolume/fvMatrices/solvers/GAMGSymSolver/GAMGAgglomerations/faceAreaPairGAMGAgglomeration/faceAreaPairGAMGAgglomeration.C b/src/finiteVolume/fvMatrices/solvers/GAMGSymSolver/GAMGAgglomerations/faceAreaPairGAMGAgglomeration/faceAreaPairGAMGAgglomeration.C
index 9bfcda020c..42a35f5c1b 100644
--- a/src/finiteVolume/fvMatrices/solvers/GAMGSymSolver/GAMGAgglomerations/faceAreaPairGAMGAgglomeration/faceAreaPairGAMGAgglomeration.C
+++ b/src/finiteVolume/fvMatrices/solvers/GAMGSymSolver/GAMGAgglomerations/faceAreaPairGAMGAgglomeration/faceAreaPairGAMGAgglomeration.C
@@ -90,8 +90,6 @@ Foam::faceAreaPairGAMGAgglomeration::faceAreaPairGAMGAgglomeration
 :
     pairGAMGAgglomeration(mesh, controlDict)
 {
-    vectorField n(faceAreas/mag(faceAreas));
-
     //agglomerate(mesh, sqrt(mag(faceAreas)));
     agglomerate
     (
@@ -100,7 +98,8 @@ Foam::faceAreaPairGAMGAgglomeration::faceAreaPairGAMGAgglomeration
         (
             cmptMultiply
             (
-                n,
+                faceAreas
+               /sqrt(mag(faceAreas)),
                 vector(1, 1.01, 1.02)
                 //vector::one
             )

From 6d3cfe9848aba235d36735bf848452354cc6a511 Mon Sep 17 00:00:00 2001
From: mattijs <mattijs>
Date: Tue, 14 May 2013 20:42:54 +0100
Subject: [PATCH 2/5] ENH: GAMGAgglomeration: enable debug printing by default

---
 etc/controlDict | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/etc/controlDict b/etc/controlDict
index b9c41cb3a4..fba02069de 100644
--- a/etc/controlDict
+++ b/etc/controlDict
@@ -135,7 +135,7 @@ DebugSwitches
     FDIC                0;
     FaceCellWave        0;
     GAMG                0;
-    GAMGAgglomeration   0;
+    GAMGAgglomeration   1;
     GAMGInterface       0;
     GAMGInterfaceField  0;
     Gamma               0;

From 8009617b23ec4d96c5cc8652d73bef48a2ad9a66 Mon Sep 17 00:00:00 2001
From: mattijs <mattijs>
Date: Tue, 14 May 2013 20:44:40 +0100
Subject: [PATCH 3/5] ENH: wordIOList: return columnsizes when printing table

---
 .../primitives/strings/word/wordIOList.C       | 18 +++++++++++++++---
 .../primitives/strings/word/wordIOList.H       |  3 ++-
 2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/src/OpenFOAM/primitives/strings/word/wordIOList.C b/src/OpenFOAM/primitives/strings/word/wordIOList.C
index ede987af53..58456cb0ac 100644
--- a/src/OpenFOAM/primitives/strings/word/wordIOList.C
+++ b/src/OpenFOAM/primitives/strings/word/wordIOList.C
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           | Copyright (C) 2012 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2012-2013 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -38,12 +38,17 @@ namespace Foam
 }
 
 
-void Foam::printTable(const List<wordList>& wll, Ostream& os)
+void Foam::printTable
+(
+    const List<wordList>& wll,
+    List<string::size_type>& columnWidth,
+    Ostream& os
+)
 {
     if (!wll.size()) return;
 
     // Find the maximum word length for each column
-    List<string::size_type> columnWidth(wll[0].size(), string::size_type(0));
+    columnWidth.setSize(wll[0].size(), string::size_type(0));
     forAll(columnWidth, j)
     {
         forAll(wll, i)
@@ -75,4 +80,11 @@ void Foam::printTable(const List<wordList>& wll, Ostream& os)
 }
 
 
+void Foam::printTable(const List<wordList>& wll, Ostream& os)
+{
+    List<string::size_type> columnWidth;
+    printTable(wll, columnWidth, os);
+}
+
+
 // ************************************************************************* //
diff --git a/src/OpenFOAM/primitives/strings/word/wordIOList.H b/src/OpenFOAM/primitives/strings/word/wordIOList.H
index c560a33a95..da9d5aa426 100644
--- a/src/OpenFOAM/primitives/strings/word/wordIOList.H
+++ b/src/OpenFOAM/primitives/strings/word/wordIOList.H
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           | Copyright (C) 2012 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2012-2013 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -43,6 +43,7 @@ namespace Foam
     typedef IOList<wordList> wordListIOList;
 
     // Print word list list as a table
+    void printTable(const List<wordList>&, List<string::size_type>&, Ostream&);
     void printTable(const List<wordList>&, Ostream&);
 }
 

From 1df4f9e8f6555b41091391b6ed26817f8ee07454 Mon Sep 17 00:00:00 2001
From: mattijs <mattijs>
Date: Tue, 14 May 2013 20:48:38 +0100
Subject: [PATCH 4/5] ENH: lduPrimitiveMesh: make constructor easier

---
 src/OpenFOAM/meshes/lduMesh/lduPrimitiveMesh.C | 6 ++++--
 src/OpenFOAM/meshes/lduMesh/lduPrimitiveMesh.H | 2 +-
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/OpenFOAM/meshes/lduMesh/lduPrimitiveMesh.C b/src/OpenFOAM/meshes/lduMesh/lduPrimitiveMesh.C
index 070edd4b69..507fc425ef 100644
--- a/src/OpenFOAM/meshes/lduMesh/lduPrimitiveMesh.C
+++ b/src/OpenFOAM/meshes/lduMesh/lduPrimitiveMesh.C
@@ -254,7 +254,7 @@ Foam::lduPrimitiveMesh::lduPrimitiveMesh
     const label nCells,
     labelList& l,
     labelList& u,
-    const Xfer<PtrList<const lduInterface> >& primitiveInterfaces,
+    PtrList<const lduInterface>& primitiveInterfaces,
     const lduSchedule& ps,
     const label comm
 )
@@ -262,10 +262,12 @@ Foam::lduPrimitiveMesh::lduPrimitiveMesh
     lduAddressing(nCells),
     lowerAddr_(l, true),
     upperAddr_(u, true),
-    primitiveInterfaces_(primitiveInterfaces),
+    primitiveInterfaces_(0),
     patchSchedule_(ps),
     comm_(comm)
 {
+    primitiveInterfaces_.transfer(primitiveInterfaces);
+
     // Create interfaces
     interfaces_.setSize(primitiveInterfaces_.size());
     forAll(primitiveInterfaces_, i)
diff --git a/src/OpenFOAM/meshes/lduMesh/lduPrimitiveMesh.H b/src/OpenFOAM/meshes/lduMesh/lduPrimitiveMesh.H
index 66c26dc37e..5bd7901c8b 100644
--- a/src/OpenFOAM/meshes/lduMesh/lduPrimitiveMesh.H
+++ b/src/OpenFOAM/meshes/lduMesh/lduPrimitiveMesh.H
@@ -133,7 +133,7 @@ public:
             const label nCells,
             labelList& l,
             labelList& u,
-            const Xfer<PtrList<const lduInterface> >& primitiveInterfaces,
+            PtrList<const lduInterface>& primitiveInterfaces,
             const lduSchedule& ps,
             const label comm
         );

From f3b7047a75e3dfcef4b859b2e29eba0e4a7ff55c Mon Sep 17 00:00:00 2001
From: mattijs <mattijs>
Date: Tue, 14 May 2013 20:50:33 +0100
Subject: [PATCH 5/5] ENH: procFaces: new GAMGProcAgglomeration method

---
 src/OpenFOAM/Make/files                       |   6 +-
 .../GAMGAgglomerateLduAddressing.C            |   2 +-
 .../GAMGAgglomeration/GAMGAgglomeration.C     |  99 +++++-
 .../pairGAMGAgglomeration.H                   |  17 +-
 .../procFacesGAMGProcAgglomeration.C          | 333 ++++++++++++++++++
 .../procFacesGAMGProcAgglomeration.H          | 136 +++++++
 6 files changed, 566 insertions(+), 27 deletions(-)
 create mode 100644 src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/procFacesGAMGProcAgglomeration/procFacesGAMGProcAgglomeration.C
 create mode 100644 src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/procFacesGAMGProcAgglomeration/procFacesGAMGProcAgglomeration.H

diff --git a/src/OpenFOAM/Make/files b/src/OpenFOAM/Make/files
index 19a8138fe5..6d346617c1 100644
--- a/src/OpenFOAM/Make/files
+++ b/src/OpenFOAM/Make/files
@@ -331,10 +331,8 @@ eagerGAMGProcAgglomeration = $(GAMGProcAgglomerations)/eagerGAMGProcAgglomeratio
 $(eagerGAMGProcAgglomeration)/eagerGAMGProcAgglomeration.C
 noneGAMGProcAgglomeration = $(GAMGProcAgglomerations)/noneGAMGProcAgglomeration
 $(noneGAMGProcAgglomeration)/noneGAMGProcAgglomeration.C
-/*
-cellFaceRatioGAMGProcAgglomeration = $(GAMGProcAgglomerations)/cellFaceRatioGAMGProcAgglomeration
-$(cellFaceRatioGAMGProcAgglomeration)/cellFaceRatioGAMGProcAgglomeration.C
-*/
+procFacesGAMGProcAgglomeration = $(GAMGProcAgglomerations)/procFacesGAMGProcAgglomeration
+$(procFacesGAMGProcAgglomeration)/procFacesGAMGProcAgglomeration.C
 
 
 meshes/lduMesh/lduMesh.C
diff --git a/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGAgglomerations/GAMGAgglomeration/GAMGAgglomerateLduAddressing.C b/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGAgglomerations/GAMGAgglomeration/GAMGAgglomerateLduAddressing.C
index e6781ed23f..066aa39d3b 100644
--- a/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGAgglomerations/GAMGAgglomeration/GAMGAgglomerateLduAddressing.C
+++ b/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGAgglomerations/GAMGAgglomeration/GAMGAgglomerateLduAddressing.C
@@ -351,7 +351,7 @@ void Foam::GAMGAgglomeration::agglomerateLduAddressing
     );
 
 
-    if (debug)
+    if (debug & 2)
     {
         Pout<< "GAMGAgglomeration :"
             << " agglomerated level " << fineLevelIndex
diff --git a/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGAgglomerations/GAMGAgglomeration/GAMGAgglomeration.C b/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGAgglomerations/GAMGAgglomeration/GAMGAgglomeration.C
index d1551eb399..a53a5fe9ab 100644
--- a/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGAgglomerations/GAMGAgglomeration/GAMGAgglomeration.C
+++ b/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGAgglomerations/GAMGAgglomeration/GAMGAgglomeration.C
@@ -27,9 +27,9 @@ License
 #include "lduMesh.H"
 #include "lduMatrix.H"
 #include "Time.H"
-#include "dlLibraryTable.H"
 #include "GAMGInterface.H"
 #include "GAMGProcAgglomeration.H"
+#include "IOmanip.H"
 
 // * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
 
@@ -67,23 +67,94 @@ void Foam::GAMGAgglomeration::compactLevels(const label nCreatedLevels)
         procBoundaryFaceMap_.setSize(nCreatedLevels);
 
         procAgglomeratorPtr_().agglomerate();
-    }
 
-    if (debug)
-    {
-        for (label levelI = 0; levelI <= size(); levelI++)
+
+        if (debug)
         {
-            if (hasMeshLevel(levelI))
+
+            Info<< "GAMGAgglomeration:" << nl
+                << "    local agglomerator     : " << type() << nl
+                << "    processor agglomerator : "
+                << procAgglomeratorPtr_().type() << nl
+                << nl;
+
+            Info<< setw(40) << "nCells"
+                << setw(24) << "nInterfaces"
+                << setw(24) << "Ratio" << nl
+                << setw(8) << "Level"
+                << setw(8) << "nProcs"
+                << "        "
+                << setw(8) << "avg"
+                << setw(8) << "max"
+                << "        "
+                << setw(8) << "avg"
+                << setw(8) << "max"
+                << "            " << setw(4) << "avg"
+                << "    " << setw(4) << "max"
+                << nl
+                << setw(8) << "-----"
+                << setw(8) << "------"
+                << "        "
+                << setw(8) << "---"
+                << setw(8) << "---"
+                << "        "
+                << setw(8) << "---"
+                << setw(8) << "---"
+                << "            " << setw(4) << "---"
+                << "    " << setw(4) << "---"
+                << nl;
+
+            for (label levelI = 0; levelI <= size(); levelI++)
             {
-                const lduMesh& fineMesh = meshLevel(levelI);
-                Pout<< "Level " << levelI << " fine mesh:"<< nl;
-                Pout<< fineMesh.info() << endl;
-            }
-            else
-            {
-                Pout<< "Level " << levelI << " has no fine mesh:" << nl
-                    << endl;
+                label nProcs = 0;
+                label nCells = 0;
+                label nInterfaces = 0;
+                label nIntFaces = 0;
+                scalar ratio = 0.0;
+
+                if (hasMeshLevel(levelI))
+                {
+                    nProcs = 1;
+
+                    const lduMesh& fineMesh = meshLevel(levelI);
+                    nCells = fineMesh.lduAddr().size();
+
+                    const lduInterfacePtrsList interfaces =
+                        fineMesh.interfaces();
+                    forAll(interfaces, i)
+                    {
+                        if (interfaces.set(i))
+                        {
+                            nInterfaces++;
+                            nIntFaces += interfaces[i].faceCells().size();
+                        }
+                    }
+                    ratio = scalar(nIntFaces)/nCells;
+                }
+
+                label totNprocs = returnReduce(nProcs, sumOp<label>());
+
+                label maxNCells = returnReduce(nCells, maxOp<label>());
+                label totNCells = returnReduce(nCells, sumOp<label>());
+
+                label maxNInt = returnReduce(nInterfaces, maxOp<label>());
+                label totNInt = returnReduce(nInterfaces, sumOp<label>());
+
+                scalar maxRatio = returnReduce(ratio, maxOp<scalar>());
+                scalar totRatio = returnReduce(ratio, sumOp<scalar>());
+
+                Info<< setw(8) << levelI
+                    << setw(8) << totNprocs
+                    << setw(16) << totNCells/totNprocs
+                    << setw(8) << maxNCells
+                    << setw(16) << totNInt/totNprocs
+                    << setw(8) << maxNInt
+                    << "        "
+                    << setw(8) << setprecision(4) << totRatio/totNprocs
+                    << setw(8) << setprecision(4) << maxRatio
+                    << nl;
             }
+            Info<< endl;
         }
     }
 }
diff --git a/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGAgglomerations/pairGAMGAgglomeration/pairGAMGAgglomeration.H b/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGAgglomerations/pairGAMGAgglomeration/pairGAMGAgglomeration.H
index 2867cac2f6..59de4b1e4d 100644
--- a/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGAgglomerations/pairGAMGAgglomeration/pairGAMGAgglomeration.H
+++ b/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGAgglomerations/pairGAMGAgglomeration/pairGAMGAgglomeration.H
@@ -61,14 +61,6 @@ protected:
 
     // Protected Member Functions
 
-        //- Calculate and return agglomeration of given level
-        tmp<labelField> agglomerate
-        (
-            label& nCoarseCells,
-            const lduAddressing& fineMatrixAddressing,
-            const scalarField& faceWeights
-        );
-
         //- Agglomerate all levels starting from the given face weights
         void agglomerate
         (
@@ -97,6 +89,15 @@ public:
             const lduMesh& mesh,
             const dictionary& controlDict
         );
+
+        //- Calculate and return agglomeration
+        static tmp<labelField> agglomerate
+        (
+            label& nCoarseCells,
+            const lduAddressing& fineMatrixAddressing,
+            const scalarField& faceWeights
+        );
+
 };
 
 
diff --git a/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/procFacesGAMGProcAgglomeration/procFacesGAMGProcAgglomeration.C b/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/procFacesGAMGProcAgglomeration/procFacesGAMGProcAgglomeration.C
new file mode 100644
index 0000000000..6e13d52c99
--- /dev/null
+++ b/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/procFacesGAMGProcAgglomeration/procFacesGAMGProcAgglomeration.C
@@ -0,0 +1,333 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2013 OpenFOAM Foundation
+     \\/     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 3 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, see <http://www.gnu.org/licenses/>.
+
+\*---------------------------------------------------------------------------*/
+
+#include "procFacesGAMGProcAgglomeration.H"
+#include "addToRunTimeSelectionTable.H"
+#include "GAMGAgglomeration.H"
+#include "Random.H"
+#include "lduMesh.H"
+#include "processorLduInterface.H"
+#include "processorGAMGInterface.H"
+#include "pairGAMGAgglomeration.H"
+
+// * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
+
+namespace Foam
+{
+    defineTypeNameAndDebug(procFacesGAMGProcAgglomeration, 0);
+
+    addToRunTimeSelectionTable
+    (
+        GAMGProcAgglomeration,
+        procFacesGAMGProcAgglomeration,
+        GAMGAgglomeration
+    );
+}
+
+
+// * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
+
+// Create single cell mesh
+Foam::autoPtr<Foam::lduPrimitiveMesh>
+Foam::procFacesGAMGProcAgglomeration::singleCellMesh
+(
+    const label singleCellMeshComm,
+    const lduMesh& mesh,
+    scalarField& faceWeights
+) const
+{
+    // Count number of faces per processor
+    List<Map<label> > procFaces(UPstream::nProcs(mesh.comm()));
+    Map<label>& myNeighbours = procFaces[UPstream::myProcNo(mesh.comm())];
+
+    {
+        const lduInterfacePtrsList interfaces(mesh.interfaces());
+        forAll(interfaces, intI)
+        {
+            if (interfaces.set(intI))
+            {
+                const processorLduInterface& pp =
+                    refCast<const processorLduInterface>
+                    (
+                        interfaces[intI]
+                    );
+                label size = interfaces[intI].faceCells().size();
+                myNeighbours.insert(pp.neighbProcNo(), size);
+            }
+        }
+    }
+
+    Pstream::gatherList(procFaces, Pstream::msgType(), mesh.comm());
+    Pstream::scatterList(procFaces, Pstream::msgType(), mesh.comm());
+
+    autoPtr<lduPrimitiveMesh> singleCellMeshPtr;
+
+    if (Pstream::master(mesh.comm()))
+    {
+        // I am master
+        label nCells = Pstream::nProcs(mesh.comm());
+
+        DynamicList<label> l(3*nCells);
+        DynamicList<label> u(3*nCells);
+        DynamicList<scalar> weight(3*nCells);
+
+        DynamicList<label> nbrs;
+        DynamicList<scalar> weights;
+
+        forAll(procFaces, procI)
+        {
+            const Map<label>& neighbours = procFaces[procI];
+
+            // Add all the higher processors
+            nbrs.clear();
+            weights.clear();
+            forAllConstIter(Map<label>, neighbours, iter)
+            {
+                if (iter.key() > procI)
+                {
+                    nbrs.append(iter.key());
+                    weights.append(iter());
+                }
+                sort(nbrs);
+                forAll(nbrs, i)
+                {
+                    l.append(procI);
+                    u.append(nbrs[i]);
+                    weight.append(weights[i]);
+                }
+            }
+        }
+
+        faceWeights.transfer(weight);
+
+        PtrList<const lduInterface> primitiveInterfaces(0);
+        const lduSchedule ps(0);
+
+        singleCellMeshPtr.reset
+        (
+            new lduPrimitiveMesh
+            (
+                nCells,
+                l,
+                u,
+                primitiveInterfaces,
+                ps,
+                singleCellMeshComm
+            )
+        );
+    }
+    return singleCellMeshPtr;
+}
+
+
+Foam::tmp<Foam::labelField>
+Foam::procFacesGAMGProcAgglomeration::processorAgglomeration
+(
+    const lduMesh& mesh
+) const
+{
+    label singleCellMeshComm = UPstream::allocateCommunicator
+    (
+        mesh.comm(),
+        labelList(1, 0)            // only processor 0
+    );
+
+    scalarField faceWeights;
+    autoPtr<lduPrimitiveMesh> singleCellMeshPtr
+    (
+        singleCellMesh
+        (
+            singleCellMeshComm,
+            mesh,
+            faceWeights
+        )
+    );
+
+    tmp<labelField> tfineToCoarse(new labelField(0));
+    labelField& fineToCoarse = tfineToCoarse();
+
+    if (singleCellMeshPtr.valid())
+    {
+        // On master call the agglomerator
+        const lduPrimitiveMesh& singleCellMesh = singleCellMeshPtr();
+
+        label nCoarseProcs;
+        fineToCoarse = pairGAMGAgglomeration::agglomerate
+        (
+            nCoarseProcs,
+            singleCellMesh,
+            faceWeights
+        );
+
+        labelList coarseToMaster(nCoarseProcs, labelMax);
+        forAll(fineToCoarse, cellI)
+        {
+            label coarseI = fineToCoarse[cellI];
+            coarseToMaster[coarseI] = min(coarseToMaster[coarseI], cellI);
+        }
+
+        // Sort according to master and redo restriction
+        labelList newToOld;
+        sortedOrder(coarseToMaster, newToOld);
+        labelList oldToNew(invert(newToOld.size(), newToOld));
+
+        fineToCoarse = UIndirectList<label>(oldToNew, fineToCoarse)();
+    }
+
+    Pstream::scatter(fineToCoarse, Pstream::msgType(), mesh.comm());
+    UPstream::freeCommunicator(singleCellMeshComm);
+
+    return tfineToCoarse;
+}
+
+
+bool Foam::procFacesGAMGProcAgglomeration::doProcessorAgglomeration
+(
+    const lduMesh& mesh
+) const
+{
+    // Check the need for further agglomeration on all processors
+    bool doAgg = mesh.lduAddr().size() < nAgglomeratingCells_;
+    mesh.reduce(doAgg, orOp<bool>());
+    return doAgg;
+}
+
+
+// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
+
+Foam::procFacesGAMGProcAgglomeration::procFacesGAMGProcAgglomeration
+(
+    GAMGAgglomeration& agglom,
+    const dictionary& controlDict
+)
+:
+    GAMGProcAgglomeration(agglom, controlDict),
+    nAgglomeratingCells_(readLabel(controlDict.lookup("nAgglomeratingCells")))
+{}
+
+
+// * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //
+
+Foam::procFacesGAMGProcAgglomeration::~procFacesGAMGProcAgglomeration()
+{
+    forAllReverse(comms_, i)
+    {
+        if (comms_[i] != -1)
+        {
+            UPstream::freeCommunicator(comms_[i]);
+        }
+    }
+}
+
+
+// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
+
+bool Foam::procFacesGAMGProcAgglomeration::agglomerate()
+{
+    if (debug)
+    {
+        Pout<< nl << "Starting mesh overview" << endl;
+        printStats(Pout, agglom_);
+    }
+
+    if (agglom_.size() >= 1)
+    {
+        Random rndGen(0);
+
+        for
+        (
+            label fineLevelIndex = 2;
+            fineLevelIndex < agglom_.size();
+            fineLevelIndex++
+        )
+        {
+            if (agglom_.hasMeshLevel(fineLevelIndex))
+            {
+                // Get the fine mesh
+                const lduMesh& levelMesh = agglom_.meshLevel(fineLevelIndex);
+
+                label levelComm = levelMesh.comm();
+                label nProcs = UPstream::nProcs(levelComm);
+
+                if (nProcs > 1 && doProcessorAgglomeration(levelMesh))
+                {
+                    tmp<labelField> tprocAgglomMap
+                    (
+                        processorAgglomeration(levelMesh)
+                    );
+                    const labelField& procAgglomMap = tprocAgglomMap();
+
+                    // Master processor
+                    labelList masterProcs;
+                    // Local processors that agglomerate. agglomProcIDs[0] is in
+                    // masterProc.
+                    List<int> agglomProcIDs;
+                    GAMGAgglomeration::calculateRegionMaster
+                    (
+                        levelComm,
+                        procAgglomMap,
+                        masterProcs,
+                        agglomProcIDs
+                    );
+
+                    // Allocate a communicator for the processor-agglomerated
+                    // matrix
+                    comms_.append
+                    (
+                        UPstream::allocateCommunicator
+                        (
+                            levelComm,
+                            masterProcs
+                        )
+                    );
+
+
+                    // Use procesor agglomeration maps to do the actual
+                    // collecting.
+                    GAMGProcAgglomeration::agglomerate
+                    (
+                        fineLevelIndex,
+                        procAgglomMap,
+                        masterProcs,
+                        agglomProcIDs,
+                        comms_.last()
+                    );
+                }
+            }
+        }
+    }
+
+    // Print a bit
+    if (debug)
+    {
+        Pout<< nl << "Agglomerated mesh overview" << endl;
+        printStats(Pout, agglom_);
+    }
+
+    return true;
+}
+
+
+// ************************************************************************* //
diff --git a/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/procFacesGAMGProcAgglomeration/procFacesGAMGProcAgglomeration.H b/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/procFacesGAMGProcAgglomeration/procFacesGAMGProcAgglomeration.H
new file mode 100644
index 0000000000..5c574c4158
--- /dev/null
+++ b/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/procFacesGAMGProcAgglomeration/procFacesGAMGProcAgglomeration.H
@@ -0,0 +1,136 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2013 OpenFOAM Foundation
+     \\/     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 3 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, see <http://www.gnu.org/licenses/>.
+
+Class
+    Foam::procFacesGAMGProcAgglomeration
+
+Description
+    Processor agglomeration of GAMGAgglomerations. Needs nAgglomeratingCells
+    which is when to start agglomerating processors. Processors get agglomerated
+    by constructing a single cell mesh for each processor with each
+    processor interface a face. This then gets agglomerated using
+    the pairGAMGAgglomeration algorithm with the number of faces
+    on the original processor interface as face weight.
+
+SourceFiles
+    procFacesGAMGProcAgglomeration.C
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef procFacesGAMGProcAgglomeration_H
+#define procFacesGAMGProcAgglomeration_H
+
+#include "GAMGProcAgglomeration.H"
+#include "DynamicList.H"
+#include "labelField.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+
+class GAMGAgglomeration;
+class lduMesh;
+class lduPrimitiveMesh;
+
+/*---------------------------------------------------------------------------*\
+                    Class procFacesGAMGProcAgglomeration Declaration
+\*---------------------------------------------------------------------------*/
+
+class procFacesGAMGProcAgglomeration
+:
+    public GAMGProcAgglomeration
+{
+    // Private data
+
+        //- When to processor agglomerate
+        const label nAgglomeratingCells_;
+
+        //- Allocated communicators
+        DynamicList<label> comms_;
+
+    // Private Member Functions
+
+        //- Return (on master) all single-cell meshes collected. single-cell
+        //  meshes are just one cell with all proc faces intact.
+        autoPtr<lduPrimitiveMesh> singleCellMesh
+        (
+            const label singleCellMeshComm,
+            const lduMesh& mesh,
+            scalarField& faceWeights
+        ) const;
+
+        //- Construct processor agglomeration: for every processor the
+        //  coarse processor-cluster it agglomerates onto
+        tmp<labelField> processorAgglomeration(const lduMesh&) const;
+
+        //- Do we need to agglomerate across processors?
+        bool doProcessorAgglomeration(const lduMesh&) const;
+
+        //- Disallow default bitwise copy construct
+        procFacesGAMGProcAgglomeration
+        (
+            const procFacesGAMGProcAgglomeration&
+        );
+
+        //- Disallow default bitwise assignment
+        void operator=(const procFacesGAMGProcAgglomeration&);
+
+
+public:
+
+    //- Runtime type information
+    TypeName("procFaces");
+
+
+    // Constructors
+
+        //- Construct given agglomerator and controls
+        procFacesGAMGProcAgglomeration
+        (
+            GAMGAgglomeration& agglom,
+            const dictionary& controlDict
+        );
+
+
+    //- Destructor
+    virtual ~procFacesGAMGProcAgglomeration();
+
+
+    // Member Functions
+
+       //- Modify agglomeration. Return true if modified
+        virtual bool agglomerate();
+
+};
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //