Add translations customization for disconnected neighbor

Author: ChengHauYang

include/mesh/mesh_base.h

@@ -36,6 +36,8 @@
 #include <string>
 #include <memory>
 
+#include "libmesh/vector_value.h"
+
 // periodic boundary condition support
 // Use forward declarations inside the libMesh namespace
 namespace libMesh
@@ -1833,7 +1835,8 @@ class MeshBase : public ParallelObject
    * Register a pair of boundaries as disconnected boundaries.
    */
   void add_disconnected_boundaries(const boundary_id_type b1,
-                                   const boundary_id_type b2);
+                                   const boundary_id_type b2,
+                                   const RealVectorValue & translation);
 
   PeriodicBoundaries * get_disconnected_boundaries();
 

src/mesh/mesh_base.C

@@ -1962,15 +1962,16 @@ void MeshBase::detect_interior_parents()
    * Register a pair of boundaries as disconnected boundaries.
    */
   void MeshBase::add_disconnected_boundaries(const boundary_id_type b1,
-                                  const boundary_id_type b2)
+                                             const boundary_id_type b2,
+                                             const RealVectorValue & translation)
     {
       // Lazily allocate the container the first time it’s needed
       if (!_disconnected_boundary_pairs)
         _disconnected_boundary_pairs = std::make_unique<PeriodicBoundaries>();
 
       // Create forward and inverse boundary mappings
-      PeriodicBoundary forward(RealVectorValue(0., 0., 0.));
-      PeriodicBoundary inverse(RealVectorValue(0., 0., 0.));
+      PeriodicBoundary forward(translation);
+      PeriodicBoundary inverse(translation * -1.0);
 
       forward.myboundary       = b1;
       forward.pairedboundary   = b2;

src/mesh/unstructured_mesh.C

@@ -998,16 +998,14 @@ void UnstructuredMesh::find_neighbors (const bool reset_remote_elements,
   }
 
 #ifdef LIBMESH_ENABLE_PERIODIC
+  // Get the disconnected boundaries object (from periodic BCs)
   auto * db = this->get_disconnected_boundaries();
 
   if (db)
     {
       // Obtain a point locator
       std::unique_ptr<PointLocatorBase> point_locator = this->sub_point_locator();
 
-      // Get the disconnected boundaries object (from periodic BCs)
-      auto * db = this->get_disconnected_boundaries();
-
       for (const auto & element : this->element_ptr_range())
         {
           for (auto ms : element->side_index_range())