BUG: snappyMultiRegionHeaterImplicit: fix decomposition. Fixes #2657

tutorials/heatTransfer/chtMultiRegionFoam/snappyMultiRegionHeaterImplicit/Allrun

@@ -16,8 +16,14 @@ runApplication blockMesh
 runApplication surfaceFeatureExtract
 
 runApplication snappyHexMesh -overwrite
-runApplication topoSet -dict system/topoSetDict.f1
 
+#- Alternatively if snappyHexMesh has not set the faceZones correctly
+#  can do some topoSet magic:
+#   - pick up the outside of the cellZones
+#   - put into faceZones
+#runApplication topoSet -dict system/topoSetDict.f1
+
+# Use faceZones in combination with preserveFaceZones constraint
 runApplication $decompDict decomposePar
 
 # Restore initial fields

tutorials/heatTransfer/chtMultiRegionFoam/snappyMultiRegionHeaterImplicit/system/decomposeParDict

@@ -27,7 +27,17 @@ constraints
     faces
     {
         type    preserveFaceZones;
-        zones   (f1 f2 f3 f4 f5);
+        zones
+        (
+            heater_to_bottomAir
+            heater_to_leftSolid
+            heater_to_rightSolid
+            heater_to_topAir
+            leftSolid_to_bottomAir
+            leftSolid_to_topAir
+            rightSolid_to_bottomAir
+            rightSolid_to_topAir
+        );
         enabled true;
     }
 }