StackLattice implementation

docs/source/methods/geometry.rst

@@ -549,6 +549,45 @@ volumetric units of the lattice will be referred to as "tiles".  Tiles are
 identified by thier indices, and the process of discovering which tile contains
 the particle is referred to as "indexing".
 
+Stack Lattice Indexing
+----------------------
+
+Indices are assigned to tiles in a stack lattice based on the tile's
+position along the axis of orientation (the :math:`x`, :math:`y`, or 
+:math:`z` axis). Figure :num:`fig-stack-lat` maps the indices for a
+stack lattice. The index, (1), maps to the bottom tile. (5) maps to
+the top tile.
+
+
+.. _fig-stack-lat:
+
+.. figure:: ../_images/stack_lat.svg
+   :align: center
+   :figclass: align-center
+   :width: 400px
+
+   Stack lattice tile indices.
+
+In general, a lattice tile is specified by the single index,
+:math:`(i)`.  If a particle's current coordinates are :math:`(x, y, z)` 
+and the lattice is oriented in the :math:`z` direction, then the index
+of a tile in a uniform stack lattice can be determined from this formula:
+
+.. math::
+    :label: stack_indexing
+
+    i = \left \lfloor \frac{z - z_0}{p} \right \rfloor
+
+where :math:`(z_0)` is the coordinate to the base of the lattice, and 
+:math:`p` is the pitch along the :math:`z` axis. Similar equations govern
+uniform stack lattices aligned with the :math:`x` and :math:`y` axes.
+
+
+The index of a tile in a nonuniform stack lattice (i.e. a stack lattice where 
+tiles have differing dimensions) does not have a closed-form equation. It can
+only be found numerically.
+
+
 Rectilinear Lattice Indexing
 ----------------------------
 

docs/source/pythonapi/base.rst

@@ -92,6 +92,7 @@ Building geometry
    openmc.DAGMCUniverse
    openmc.RectLattice
    openmc.HexLattice
+   openmc.StackLattice
    openmc.Geometry
 
 Many of the above classes are derived from several abstract classes:

docs/source/usersguide/geometry.rst

@@ -287,6 +287,9 @@ regular pattern such as a rectangular or hexagonal lattice. In such a case, it
 would be cumbersome to have to define the boundaries of each of the cells to be
 filled with a universe. OpenMC provides a means to define lattice structures
 through the :class:`openmc.RectLattice` and :class:`openmc.HexLattice` classes.
+Sometimes a model will have a repeated structure in only one dimension. OpenMC
+provides a means to define such structures through the
+:class:`openmc.StackLattice` class.
 
 Rectangular Lattices
 --------------------
@@ -412,6 +415,28 @@ code would work::
 If you need to create a hexagonal boundary (composed of six planar surfaces) for
 a hexagonal lattice, :func:`openmc.model.hexagonal_prism` can be used.
 
+Stack Lattices
+--------------
+A stack lattice defines a one-dimensional array of universes that are filled into stacked layers (lattice elements). These layers can be of uniform or nonuniform thickness. Creating a stack lattice is similar to creating a rectangular lattice with a few differences:
+
+The position of the central axis and coordinate of the base level of the stack
+in must be specified (:attr:`StackLattice.central_axis` and
+:attr:`StackLattice.base_coordinate`, respectively). Additionally,
+:attr:`universes` must be set before :attr:`pitch`. For nonuniform lattices, the :attr:`is_uniform` attribute must be set to ``False`` before setting :attr:`pitch`.
+
+For a uniform stack lattice, a single value for the pitch should be specified.
+It should not be a list. For a nonuniform stack lattice, an iterable of values
+should be given. The length of this iterable should match the length of
+:attr:`StackLattice.universes`.
+
+The lattice orientation is by default in the :math:`z`-direction, but this can
+be changed using the :attr:`StackLattice.orientation` attribute to :attr:`x` or
+:attr:`y`. :attr:`StackLattice.central_axis` assumes that the coordinates are
+in the :math:`(x,y)`, :math:`(x,z)`, or :math:`(y,z)` basis for
+:attr:`orientation` of :attr:`z`, :attr:`y`, or :attr:`x`, respectively.
+
+
+
 .. _usersguide_geom_export:
 
 --------------------------

include/openmc/hdf5_interface.h

@@ -52,6 +52,7 @@ inline hid_t create_group(hid_t parent_id, const std::stringstream& name)
 
 hid_t file_open(const std::string& filename, char mode, bool parallel = false);
 hid_t open_group(hid_t group_id, const std::string& name);
+void write_bool(hid_t group_id, const char* name, bool b, bool indep);
 void write_string(
   hid_t group_id, const char* name, const std::string& buffer, bool indep);
 
@@ -109,6 +110,8 @@ void write_double(hid_t group_id, int ndim, const hsize_t* dims,
   const char* name, const double* buffer, bool indep);
 void write_int(hid_t group_id, int ndim, const hsize_t* dims, const char* name,
   const int* buffer, bool indep);
+void write_bool(hid_t group_id, int ndim, const hsize_t* dims, const char* name,
+  const hbool_t* buffer, bool indep);
 void write_llong(hid_t group_id, int ndim, const hsize_t* dims,
   const char* name, const long long* buffer, bool indep);
 void write_string(hid_t group_id, int ndim, const hsize_t* dims, size_t slen,