A slightly safer method for writing out meshes independent of library.

include/openmc/mesh.h

@@ -325,6 +325,7 @@ public:
   void to_hdf5(hid_t group) const override;
 
   // Data members
+  bool output_ {true};
   std::string filename_; //!< Path to unstructured mesh file
 };
 

openmc/mesh.py

@@ -618,6 +618,9 @@ class UnstructuredMesh(MeshBase):
         Name of the file containing the unstructured mesh
     library : str
         Mesh library used for the unstructured mesh tally
+    output : bool
+        Indicates whether or not automatic tally output should
+        be generated for this mesh
     volumes : Iterable of float
         Volumes of the unstructured mesh elements
     total_volume : float
@@ -626,13 +629,13 @@ class UnstructuredMesh(MeshBase):
         An iterable of element centroid coordinates, e.g. [(0.0, 0.0, 0.0),
         (1.0, 1.0, 1.0), ...]
     """
-
     def __init__(self, filename, library, mesh_id=None, name=''):
         super().__init__(mesh_id, name)
         self.filename = filename
         self._volumes = None
         self._centroids = None
         self.library = library
+        self._output = True
 
     @property
     def filename(self):
@@ -661,6 +664,15 @@ class UnstructuredMesh(MeshBase):
         cv.check_type("Unstructured mesh size", size, Integral)
         self._size = size
 
+    @property
+    def output(self):
+        return self._output
+
+    @output.setter
+    def output(self, val):
+        cv.check_type("Unstructured mesh output value", val, bool)
+        self._output = val
+
     @property
     def volumes(self):
         return self._volumes

src/mesh.cpp

@@ -138,6 +138,13 @@ UnstructuredMesh::UnstructuredMesh(pugi::xml_node node) : Mesh(node) {
     fatal_error("No filename supplied for unstructured mesh with ID: " +
                 std::to_string(id_));
   }
+
+  // check if mesh tally data should be written with
+  // statepoint files
+  if (check_for_node(node, "output")) {
+    output_ = get_node_value_bool(node, "output");
+  }
+
 }
 
 std::string
@@ -2294,6 +2301,7 @@ LibMesh::set_score_data(const std::string& var_name,
 
 void LibMesh::write(std::string filename) const {
   std::cout << "Writing file : " << filename + ".e" << std::endl;
+
   libMesh::ExodusII_IO exo(*m_);
   std::set<std::string> systems_out = {eq_system_name_};
   exo.write_discontinuous_exodusII(filename + ".e", *equation_systems_, &systems_out);

src/state_point.cpp

@@ -788,6 +788,8 @@ void write_unstructured_mesh_results() {
 
       if (!umesh) continue;
 
+      if (!umesh->output_) continue;
+
       // if this tally has more than one filter, print
       // warning and skip writing the mesh
       if (tally->filters().size() > 1) {
@@ -857,6 +859,9 @@ void write_unstructured_mesh_results() {
                                          tally->id_,
                                          simulation::current_batch,
                                          w);
+
+      if (umesh->library() == "moab" && !mpi::master) continue;
+
       // Write the unstructured mesh and data to file
       umesh->write(filename);