Differentiate materials in DAGMC universes

docs/source/io_formats/geometry.rst

@@ -407,13 +407,33 @@ Each ``<dagmc_universe>`` element can have the following attributes or sub-eleme
 
     *Default*: None
 
+  :material_overrides:
+    This element contains information on material overrides to be applied to the
+    DAGMC universe. It has the following sub-elements:
 
-  .. note:: A geometry.xml file containing only a DAGMC model for a file named `dagmc.h5m` (no CSG)
-            looks as follows
+    :cell:
+      Material override information for a single cell. It contains the following
+      attributes:
 
-            .. code-block:: xml
+      :id:
+        The cell ID in the DAGMC geometry for which the material override will
+        apply.
 
-              <?xml version='1.0' encoding='utf-8'?>
-              <geometry>
-                <dagmc_universe filename="dagmc.h5m" id="1" />
-              </geometry>
+      :material:
+        A list of material IDs that will apply to instances of the cell. If the
+        list contains only one ID, it will replace the original material
+        assignment of all instances of the DAGMC cell. If the list contains more
+        than one material, each material ID of the list will be assigned to the
+        various instances of the DAGMC cell.
+
+    *Default*: None
+
+.. note:: A geometry.xml file containing only a DAGMC model for a file named
+          `dagmc.h5m` (no CSG) looks as follows:
+
+    .. code-block:: xml
+
+        <?xml version='1.0' encoding='utf-8'?>
+        <geometry>
+          <dagmc_universe filename="dagmc.h5m" id="1" />
+        </geometry>

docs/source/pythonapi/capi.rst

@@ -19,6 +19,7 @@ Functions
    finalize
    find_cell
    find_material
+   dagmc_universe_cell_ids
    global_bounding_box
    global_tallies
    hard_reset

include/openmc/capi.h

@@ -29,6 +29,9 @@ int openmc_cell_set_temperature(
   int32_t index, double T, const int32_t* instance, bool set_contained = false);
 int openmc_cell_set_translation(int32_t index, const double xyz[]);
 int openmc_cell_set_rotation(int32_t index, const double rot[], size_t rot_len);
+int openmc_dagmc_universe_get_cell_ids(
+  int32_t univ_id, int32_t* ids, size_t* n);
+int openmc_dagmc_universe_get_num_cells(int32_t univ_id, size_t* n);
 int openmc_energy_filter_get_bins(
   int32_t index, const double** energies, size_t* n);
 int openmc_energy_filter_set_bins(

include/openmc/cell.h

@@ -320,7 +320,6 @@ class Cell {
   int32_t universe_;        //!< Universe # this cell is in
   int32_t fill_;            //!< Universe # filling this cell
   int32_t n_instances_ {0}; //!< Number of instances of this cell
-  GeometryType geom_type_;  //!< Geometric representation type (CSG, DAGMC)
 
   //! \brief Index corresponding to this cell in distribcell arrays
   int distribcell_index_ {C_NONE};
@@ -350,6 +349,13 @@ class Cell {
   vector<double> rotation_;
 
   vector<int32_t> offset_; //!< Distribcell offset table
+
+  // Accessors
+  const GeometryType& geom_type() const { return geom_type_; }
+  GeometryType& geom_type() { return geom_type_; }
+
+private:
+  GeometryType geom_type_; //!< Geometric representation type (CSG, DAGMC)
 };
 
 struct CellInstanceItem {

include/openmc/dagmc.h

@@ -29,6 +29,12 @@ void check_dagmc_root_univ();
 #include "openmc/particle.h"
 #include "openmc/position.h"
 #include "openmc/surface.h"
+#include "openmc/vector.h"
+
+#include <memory> // for shared_ptr, unique_ptr
+#include <string>
+#include <unordered_map>
+#include <utility> // for pair
 
 class UWUW;
 
@@ -133,6 +139,10 @@ class DAGUniverse : public Universe {
   void legacy_assign_material(
     std::string mat_string, std::unique_ptr<DAGCell>& c) const;
 
+  //! Assign a material overriding normal assignement to a cell
+  //! \param[in] c The OpenMC cell to which the material is assigned
+  void override_assign_material(std::unique_ptr<DAGCell>& c) const;
+
   //! Return the index into the model cells vector for a given DAGMC volume
   //! handle in the universe
   //! \param[in] vol MOAB handle to the DAGMC volume set
@@ -184,6 +194,11 @@ class DAGUniverse : public Universe {
                              //!< generate new material IDs for the universe
   bool has_graveyard_; //!< Indicates if the DAGMC geometry has a "graveyard"
                        //!< volume
+  std::unordered_map<int, vector<int>>
+    material_overrides_; //!< Map of material overrides
+                         //!< keys correspond to the DAGMCCell id
+                         //!< values are a list of material ids used
+                         //!< for the override
 };
 
 //==============================================================================

include/openmc/surface.h

@@ -38,7 +38,6 @@ class Surface {
   int id_;                           //!< Unique ID
   std::string name_;                 //!< User-defined name
   unique_ptr<BoundaryCondition> bc_; //!< Boundary condition
-  GeometryType geom_type_;           //!< Geometry type indicator (CSG or DAGMC)
   bool surf_source_ {false}; //!< Activate source banking for the surface?
 
   explicit Surface(pugi::xml_node surf_node);
@@ -91,6 +90,13 @@ class Surface {
   //! Get the BoundingBox for this surface.
   virtual BoundingBox bounding_box(bool /*pos_side*/) const { return {}; }
 
+  // Accessors
+  const GeometryType& geom_type() const { return geom_type_; }
+  GeometryType& geom_type() { return geom_type_; }
+
+private:
+  GeometryType geom_type_; //!< Geometry type indicator (CSG or DAGMC)
+
 protected:
   virtual void to_hdf5_inner(hid_t group_id) const = 0;
 };

openmc/__init__.py

@@ -15,6 +15,7 @@
 from openmc.weight_windows import *
 from openmc.surface import *
 from openmc.universe import *
+from openmc.dagmc import *
 from openmc.source import *
 from openmc.settings import *
 from openmc.lattice import *