Start of libmesh implementation.

CMakeLists.txt

@@ -31,6 +31,7 @@ option(debug    "Compile with debug flags"                       OFF)
 option(optimize "Turn on all compiler optimization flags"        OFF)
 option(coverage "Compile with coverage analysis flags"           OFF)
 option(dagmc    "Enable support for DAGMC (CAD) geometry"        OFF)
+option(libmesh  "Enable support for libmesh unstructured mesh tallies" OFF)
 
 #===============================================================================
 # MPI for distributed-memory parallelism
@@ -65,6 +66,14 @@ if(pugixml_FOUND)
   message(STATUS "Found pugixml: ${pugixml_DIR}")
 else()
   message(STATUS "Did not find pugixml, will use submodule instead")
+#===============================================================================
+# libMesh Unstructured Mesh Support
+#===============================================================================
+if(libmesh)
+  find_package(LIBMESH REQUIRED)
+  set(LIBMESH_LIBRARIES mesh_opt)
+  set(LIBMESH_INCLUDE_DIRS "${LIBMESH}/../include/")
+  link_directories(${LIBMESH})
 endif()
 
 #===============================================================================
@@ -405,6 +414,12 @@ if(dagmc)
   target_link_libraries(libopenmc dagmc-shared uwuw-shared)
 endif()
 
+if(libmesh)
+  target_compile_definitions(libopenmc PRIVATE LIBMESH)
+  target_link_libraries(libopenmc ${LIBMESH_LIBRARIES})
+  target_include_directories(libopenmc PRIVATE ${LIBMESH_INCLUDE_DIRS})
+endif()
+
 #===============================================================================
 # openmc executable
 #===============================================================================

cmake/Modules/FindLIBMESH.cmake

@@ -0,0 +1,21 @@
+# Try to find LIBMESH
+#
+# Once done this will define
+#
+#  LIBMESH_FOUND - system has LIBMESH
+#  LIBMESH_INCLUDE_DIRS - the LIBMESH include directory
+#  LIBMESH_LIBRARIES - Link these to use LIBMESH
+#  LIBMESH_DEFINITIONS - Compiler switches required for using LIBMESH
+
+find_path(LIBMESH NAMES libmesh_opt.so
+          HINTS ${LIBMESH_ROOT} $ENV{LIBMESH_ROOT}
+          PATHS ENV LD_LIBRARY_PATH
+          PATH_SUFFIXES lib Lib
+          NO_DEFAULT_PATH)
+
+if(DEFINED LIBMESH)
+  set(LIBMESH_FOUND TRUE)
+endif()
+
+
+message(STATUS "Found LIBMESH in ${LIBMESH}")

include/openmc/mesh.h

@@ -22,6 +22,11 @@
 #include "moab/GeomUtil.hpp"
 #endif
 
+#ifdef LIBMESH
+#include "libmesh/libmesh.h"
+#include "libmesh/mesh.h"
+#endif
+
 namespace openmc {
 
 //==============================================================================
@@ -251,6 +256,12 @@ public:
   int set_grid();
 };
 
+class UnstructuredMeshBase : public Mesh {
+public:
+  UnstructuredMeshBase(pugi::xml_node node);
+  std::string filename_;
+};
+
 #ifdef DAGMC
 
 class UnstructuredMesh : public Mesh {
@@ -422,6 +433,19 @@ private:
 
 #endif
 
+#ifdef LIBMESH
+class LibMesh : public UnstructuredMeshBase {
+
+public:
+  // constructor
+  LibMesh(pugi::xml_node node);
+
+private:
+  std::unique_ptr<libMesh::Mesh> m_;
+  std::unique_ptr<libMesh::PointLocatorBase> point_locator_;
+};
+#endif
+
 //==============================================================================
 // Non-member functions
 //==============================================================================

src/mesh.cpp

@@ -2027,6 +2027,37 @@ double UnstructuredMesh::get_volume_frac(int bin = -1) const {
 
 #endif
 
+UnstructuredMeshBase::UnstructuredMeshBase(pugi::xml_node node) : Mesh(node) {
+    // check the mesh type
+  if (check_for_node(node, "type")) {
+    auto temp = get_node_value(node, "type", true, true);
+    if (temp != "unstructured") {
+      fatal_error("Invalid mesh type: " + temp);
+    }
+  }
+
+  // get the filename of the unstructured mesh to load
+  if (check_for_node(node, "mesh_file")) {
+    filename_ = get_node_value(node, "mesh_file");
+  }
+  else {
+    fatal_error("No filename supplied for unstructured mesh with ID: " +
+                std::to_string(id_));
+  }
+}
+
+#ifdef LIBMESH
+LibMesh::LibMesh(pugi::xml_node node) : UnstructuredMeshBase(node) {
+  libMesh::LibMeshInit init(0, NULL);
+
+  m_ = std::unique_ptr<libMesh::Mesh>(new libMesh::Mesh(init.comm(), 3));
+  m_->read(filename_);
+
+  point_locator_ = m_->sub_point_locator();
+  m_->find_neighbors();
+}
+#endif
+
 //==============================================================================
 // Non-member functions
 //==============================================================================