add the ghost functor directly inside prepare_for_use()/find_neighbors()

Author: ChengHauYang

src/mesh/unstructured_mesh.C

@@ -51,6 +51,8 @@
 #include "libmesh/periodic_boundaries.h"
 #include "libmesh/periodic_boundary.h"
 
+#include <libmesh/disconnected_neighbor_coupling.h>
+
 namespace {
 
 using namespace libMesh;
@@ -1033,6 +1035,9 @@ void UnstructuredMesh::find_neighbors (const bool reset_remote_elements,
                 }
             }
         }
+
+      // Ghost the disconnected elements
+      this->add_ghosting_functor(std::make_unique<DisconnectedNeighborCoupling>(*this));
     }
 #endif // LIBMESH_ENABLE_PERIODIC
 

tests/systems/disconnected_neighbor_test.C

@@ -15,9 +15,6 @@
 #include "test_comm.h"
 #include "libmesh_cppunit.h"
 
-#include <libmesh/disconnected_neighbor_coupling.h>
-
-
 using namespace libMesh;
 
 static const Real b = 1.0;
@@ -267,9 +264,6 @@ private:
     // assertions later may fail.
     mesh.allow_renumbering(false);
 
-    // Ghost the disconnected elements
-    mesh.add_ghosting_functor(std::make_unique<DisconnectedNeighborCoupling>(mesh));
-
     mesh.prepare_for_use();
 
     // Check elem 0 (the left element)
@@ -504,9 +498,6 @@ private:
     // And, in `prepare_for_use()`, libMesh will set up the disconnected neighbor relationships.
     mesh.add_disconnected_boundaries(interface_left_id, interface_right_id, RealVectorValue(0.0, 0.0, 0.0));
 
-    // Ghost the disconnected elements
-    mesh.add_ghosting_functor(std::make_unique<DisconnectedNeighborCoupling>(mesh));
-
     mesh.prepare_for_use();
   }
 };