BUG: snappyHexMesh with -decomposeParDict option (issue #265)

- only occurs in combination with distributedTriSurfaceMesh in snappy.

- workaround similar to that previously used for surfaceRedistributePar
  (issue #60).

Minor adjustment of incompressible motorBike tutorial to detect use of
distributedTriSurfaceMesh.

applications/utilities/mesh/generation/snappyHexMesh/snappyHexMesh.C

@@ -901,33 +901,42 @@ int main(int argc, char *argv[])
 
     // Read decomposePar dictionary
     dictionary decomposeDict;
+    if (Pstream::parRun())
     {
-        if (Pstream::parRun())
-        {
-            fileName decompDictFile;
-            args.optionReadIfPresent("decomposeParDict", decompDictFile);
+        fileName decompDictFile;
+        args.optionReadIfPresent("decomposeParDict", decompDictFile);
 
-            decomposeDict = IOdictionary
+        // A demand-driven decompositionMethod can have issues finding
+        // an alternative decomposeParDict location.
+
+        IOdictionary* dictPtr = new IOdictionary
+        (
+            decompositionModel::selectIO
             (
-                decompositionModel::selectIO
+                IOobject
                 (
-                    IOobject
-                    (
-                        "decomposeParDict",
-                        runTime.system(),
-                        mesh,
-                        IOobject::MUST_READ,
-                        IOobject::NO_WRITE
-                    ),
-                    decompDictFile
-                )
-            );
-        }
-        else
-        {
-            decomposeDict.add("method", "none");
-            decomposeDict.add("numberOfSubdomains", 1);
-        }
+                    "decomposeParDict",
+                    runTime.system(),
+                    runTime,
+                    IOobject::MUST_READ,
+                    IOobject::NO_WRITE
+                ),
+                decompDictFile
+            )
+        );
+
+        // Store it on the object registry, but to be found it must also
+        // have the expected "decomposeParDict" name.
+
+        dictPtr->rename("decomposeParDict");
+        runTime.store(dictPtr);
+
+        decomposeDict = *dictPtr;
+    }
+    else
+    {
+        decomposeDict.add("method", "none");
+        decomposeDict.add("numberOfSubdomains", 1);
     }
 
 

applications/utilities/surface/surfaceRedistributePar/surfaceRedistributePar.C

@@ -161,7 +161,10 @@ int main(int argc, char *argv[])
         fileName decompDictFile;
         args.optionReadIfPresent("decomposeParDict", decompDictFile);
 
-        IOdictionary* dict = new IOdictionary
+        // A demand-driven decompositionMethod can have issues finding
+        // an alternative decomposeParDict location.
+
+        IOdictionary* dictPtr = new IOdictionary
         (
             decompositionModel::selectIO
             (
@@ -177,11 +180,11 @@ int main(int argc, char *argv[])
             )
         );
 
-        // The object must have the expected "decomposeParDict" name.
-        // This also implies that it cannot be changed during the run.
-        dict->rename("decomposeParDict");
+        // Store it on the object registry, but to be found it must also
+        // have the expected "decomposeParDict" name.
 
-        runTime.store(dict);
+        dictPtr->rename("decomposeParDict");
+        runTime.store(dictPtr);
     }
 
     // Determine mesh bounding boxes:

bin/tools/RunFunctions

@@ -56,15 +56,17 @@ isTest()
 #
 getNumberOfProcessors()
 {
+    local dict="${1:-system/decomposeParDict}"
+
     # Re-use positional parameters for automatic whitespace elimination
-    set -- $(foamDictionary -entry numberOfSubdomains -value "${1:-system/decomposeParDict}")
+    set -- $(foamDictionary -entry numberOfSubdomains -value "$dict" 2>/dev/null)
 
     if [ "$#" -eq 1 ]
     then
         echo "$1"
     else
-        echo "Error retrieving 'numberOfSubdomains' from decomposeParDict" 1>&2
-        echo 1
+        echo "Warning no 'numberOfSubdomains' in '$dict'" 1>&2
+        echo 1 # serial as fallback
         return 1
     fi
 }

tutorials/incompressible/simpleFoam/motorBike/Allrun

@@ -4,7 +4,10 @@ cd ${0%/*} || exit 1    # Run from this directory
 # Source tutorial run functions
 . $WM_PROJECT_DIR/bin/tools/RunFunctions
 
+# Alternative decomposeParDict name:
 decompDict="-decomposeParDict system/decomposeParDict.6"
+## Standard decomposeParDict name:
+# unset decompDict
 
 # copy motorbike surface from resources directory
 \cp $FOAM_TUTORIALS/resources/geometry/motorBike.obj.gz constant/triSurface/
@@ -13,6 +16,14 @@ runApplication surfaceFeatureExtract
 runApplication blockMesh
 
 runApplication decomposePar $decompDict
+
+# Using distributedTriSurfaceMesh?
+if foamDictionary -entry geometry -value system/snappyHexMeshDict | \
+   grep -q distributedTriSurfaceMesh
+then
+    runParallel $decompDict surfaceRedistributePar motorBike.obj independent
+fi
+
 runParallel $decompDict snappyHexMesh -overwrite
 
 #- For non-parallel running: - set the initial fields

tutorials/incompressible/simpleFoam/motorBike/system/decomposeParDict.6

@@ -15,20 +15,20 @@ FoamFile
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
-numberOfSubdomains 4;
+numberOfSubdomains 6;
 
 method          hierarchical;
 // method          ptscotch;
 
 simpleCoeffs
 {
-    n               (4 1 1);
+    n               (6 1 1);
     delta           0.001;
 }
 
 hierarchicalCoeffs
 {
-    n               (2 2 1);
+    n               (3 2 1);
     delta           0.001;
     order           xyz;
 }