From a3228f861a3eaf779ed3ecec35036d9f92bbb740 Mon Sep 17 00:00:00 2001
From: Andrew Heather <a.heather@opencfd.co.uk>
Date: Tue, 5 Jun 2018 15:13:13 +0100
Subject: [PATCH] ENH: GAMG agglom - more robust treatment for small meshes
---
.../GAMGAgglomeration/GAMGAgglomeration.C | 8 ++++++++
.../GAMGAgglomeration/GAMGAgglomeration.H | 18 +++++++++---------
2 files changed, 17 insertions(+), 9 deletions(-)
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 d3b63e7b9d7..b507253a199 100644
--- a/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGAgglomerations/GAMGAgglomeration/GAMGAgglomeration.C
+++ b/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGAgglomerations/GAMGAgglomeration/GAMGAgglomeration.C
@@ -265,6 +265,14 @@ Foam::GAMGAgglomeration::GAMGAgglomeration
meshLevels_(maxLevels_)
{
+ // Limit the cells in the coarsest level based on the local number of
+ // cells. Note: 2 for pair-wise
+ nCellsInCoarsestLevel_ =
+ max(1, min(mesh.lduAddr().size()/2, nCellsInCoarsestLevel_));
+
+ // Ensure all procs see the same nCellsInCoarsestLevel_
+ reduce(nCellsInCoarsestLevel_, minOp<label>());
+
procCommunicator_.setSize(maxLevels_ + 1, -1);
if (processorAgglomerate())
{
diff --git a/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGAgglomerations/GAMGAgglomeration/GAMGAgglomeration.H b/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGAgglomerations/GAMGAgglomeration/GAMGAgglomeration.H
index 9a8bb8c05c7..d258e7f8c58 100644
--- a/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGAgglomerations/GAMGAgglomeration/GAMGAgglomeration.H
+++ b/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGAgglomerations/GAMGAgglomeration/GAMGAgglomeration.H
@@ -71,7 +71,7 @@ protected:
const label maxLevels_;
//- Number of cells in coarsest level
- const label nCellsInCoarsestLevel_;
+ label nCellsInCoarsestLevel_;
//- Cached mesh interfaces
const lduInterfacePtrsList meshInterfaces_;
@@ -242,7 +242,7 @@ public:
);
//- Runtime selection table for matrix or mixed geometric/matrix
- // agglomerators
+ //- agglomerators
declareRunTimeSelectionTable
(
autoPtr,
@@ -259,7 +259,7 @@ public:
);
//- Runtime selection table for matrix or mixed geometric/matrix
- // agglomerators
+ //- agglomerators
declareRunTimeSelectionTable
(
autoPtr,
@@ -378,7 +378,7 @@ public:
}
//- Return number of coarse patch faces (before processor
- // agglomeration)
+ //- agglomeration)
const labelList& nPatchFaces(const label leveli) const
{
return nPatchFaces_[leveli];
@@ -452,14 +452,14 @@ public:
}
//- Mapping from processor to agglomerated processor (global, all
- // processors have the same information). Note that level is
- // the fine, not the coarse, level index. This is to be
- // consistent with the way the restriction is stored
+ //- processors have the same information). Note that level is
+ //- the fine, not the coarse, level index. This is to be
+ //- consistent with the way the restriction is stored
const labelList& procAgglomMap(const label fineLeveli) const;
//- Set of processors to agglomerate. Element 0 is the
- // master processor. (local, same only on those processors that
- // agglomerate)
+ //- master processor. (local, same only on those processors that
+ //- agglomerate)
const labelList& agglomProcIDs(const label fineLeveli) const;
//- Check that level has combined mesh
--
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