openmc.CMFDMesh

class openmc.CMFDMesh[source]

A structured Cartesian mesh used for Coarse Mesh Finite Difference (CMFD) acceleration.

Variables:
  • lower_left (Iterable of float) – The lower-left corner of the structured mesh. If only two coordinates are given, it is assumed that the mesh is an x-y mesh.
  • upper_right (Iterable of float) – The upper-right corner of the structrued mesh. If only two coordinates are given, it is assumed that the mesh is an x-y mesh.
  • dimension (Iterable of int) – The number of mesh cells in each direction.
  • width (Iterable of float) – The width of mesh cells in each direction.
  • energy (Iterable of float) – Energy bins in MeV, listed in ascending order (e.g. [0.0, 0.625e-7, 20.0]) for CMFD tallies and acceleration. If no energy bins are listed, OpenMC automatically assumes a one energy group calculation over the entire energy range.
  • albedo (Iterable of float) – Surface ratio of incoming to outgoing partial currents on global boundary conditions. They are listed in the following order: -x +x -y +y -z +z.
  • map (Iterable of int) –

    An optional acceleration map can be specified to overlay on the coarse mesh spatial grid. If this option is used, a 1 is used for a non-accelerated region and a 2 is used for an accelerated region. For a simple 4x4 coarse mesh with a 2x2 fuel lattice surrounded by reflector, the map is:

    [1, 1, 1, 1,
 1, 2, 2, 1,
 1, 2, 2, 1,
 1, 1, 1, 1]

    Therefore a 2x2 system of equations is solved rather than a 4x4. This is extremely important to use in reflectors as neutrons will not contribute to any tallies far away from fission source neutron regions. A 2 must be used to identify any fission source region.