ENH: faceAgglomerate: more robust. Fixes #2741

- feature angle compared to real angle
- stop agglomerating if number of marked edges does not change

src/fvAgglomerationMethods/pairPatchAgglomeration/Make/options

 EXE_INC = \
+    -I$(LIB_SRC)/fileFormats/lnInclude \
     -I$(LIB_SRC)/finiteVolume/lnInclude \
     -I$(LIB_SRC)/meshTools/lnInclude
 

src/fvAgglomerationMethods/pairPatchAgglomeration/pairPatchAgglomeration.H

@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2016-2020 OpenCFD Ltd.
+    Copyright (C) 2016-2020,2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -101,9 +101,30 @@ private:
         (
             const bPatch& patch,
             const labelList& fineToCoarse,
-            const label fineLevelIndex
+            const label fineLevelIndex,
+            label& nMarkedEdges
         );
 
+        //- Does combining facei with faceIDs produce a single face?
+        bool isSingleEdgeLoop
+        (
+            const bPatch& patch,
+            const labelList& faceIDs,
+            const label facei
+        ) const;
+
+        //- Select neighbour with highest inbetween edge weight. Either looks
+        //- at already clustered faces (addToCluster=true) or only
+        //  unclustered
+        label maxValidNeighbour
+        (
+            const bool addToCluster,
+            const bPatch& patch,
+            const label facei,
+            const labelList& coarseCellMap
+            //const labelListList& coarseToFine
+        ) const;
+
         //- Agglomerate one level
         tmp<labelField> agglomerateOneLevel
         (
@@ -121,7 +142,8 @@ private:
         bool continueAgglomerating
         (
             const label nLocal,
-            const label nLocalOld
+            const label nLocalOld,
+            const label nMarkedEdges
         );
 
         //- Set edge weights
@@ -142,6 +164,10 @@ private:
 
 public:
 
+    //- Runtime type information
+    TypeName("pairPatch");
+
+
     // Constructors
 
         //- Construct given faces, points and control dictionary
@@ -166,7 +192,7 @@ public:
 
 
     // Destructor
-    ~pairPatchAgglomeration();
+    virtual ~pairPatchAgglomeration();
 
 
     // Member Functions

tutorials/heatTransfer/chtMultiRegionFoam/externalSolarLoad/constant/air/viewFactorsDict

@@ -14,9 +14,26 @@ FoamFile
 }
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
-writeViewFactorMatrix     true;
-writePatchViewFactors     false;
-// dumpRays    true;
+
+writeViewFactorMatrix       true;
+writePatchViewFactors       false;
+
+// Write rays as lines to .obj file
+//dumpRays                    true;
+
+
+// Switch on debug for faceAgglomerate
+//debug                       1;
+writeFacesAgglomeration     true;
+patchAgglomeration
+{
+    // Do all of the view-factor patches
+    viewFactorWall
+    {
+        nFacesInCoarsestLevel   10;
+        featureAngle            45;
+    }
+}
 
 maxDynListLength          200000;