From abbd44a80ee10fffdcd4b1421f783050d8ff41bc Mon Sep 17 00:00:00 2001 From: Bryan Herman Date: Wed, 17 Oct 2012 19:02:01 -0400 Subject: [PATCH] added input description for CMFD XML input file --- docs/source/usersguide/input.rst | 188 ++++++++++++++++++++++++++++++- 1 file changed, 186 insertions(+), 2 deletions(-) diff --git a/docs/source/usersguide/input.rst b/docs/source/usersguide/input.rst index 1e750fd35..2a5b14689 100644 --- a/docs/source/usersguide/input.rst +++ b/docs/source/usersguide/input.rst @@ -37,16 +37,19 @@ Overview of Files ----------------- To assemble a complete model for OpenMC, one needs to create separate XML files -for the geometry, materials, and settings. Additionally, there are two optional +for the geometry, materials, and settings. Additionally, there are three optional input files. The first is a tallies XML file that specifies physical quantities to be tallied. The second is a plots XML file that specifies regions of geometry -which should be plotted. OpenMC expects that these files are called: +which should be plotted. The third is a CMFD XML file that specifies coarse mesh +acceleration geometry and execution parameters. OpenMC expects that these +files are called: * ``geometry.xml`` * ``materials.xml`` * ``settings.xml`` * ``tallies.xml`` * ``plots.xml`` +* ``cmfd.xml`` -------------------------------------- Settings Specification -- settings.xml @@ -979,3 +982,184 @@ sub-elements: materials to plot. This overrides any ``col_spec`` color specifications. *Default*: None + +-------------------------------------------- +CMFD Specification -- cmfd.xml +-------------------------------------------- + +Coarse mesh finite difference acceleration method has been implemented in OpenMC. +Currently, it allows users to accelerate fission source convergence during +inactive neutron batches. To run CMFD, the ```` element in +``settings.xml`` should be set to ``.true.``. + +```` Element +-------------------------- + +The ```` element controls the batch where CMFD tallies should be +reset. CMFD tallies should be reset before active batches so they are accumulated +without bias. + + *Default*: 0 + +```` Element +------------------- + +The ```` element controls what batch CMFD calculations should begin. + + *Default*: 1 + +```` Element +---------------------- + +The ```` element controls whether or not the CMFD diffusion result is +used to adjust the weight of fission source neutrons on the next OpenMC batch. +It can be turned on with ".true." and off with ".false.". + + *Default*: .false. + +```` Element +---------------------- + +The ```` element controls if cmfd tallies should be accumulated +during inactive batches. For some applications, CMFD tallies may not be +needed until the start of active batches. This option can be turned on +with ".true." and off with ".false." + + *Default*: .true. + +```` Element +---------------------- + +The ```` element specifies acceptance criteria of a CMFD eigenvalue. +If the CMFD eigenvalue and OpenMC batch eigenvalue are within this tolerance, +CMFD is allowed to modify source neutron weights. + + *Default*: 0.005 + +```` Element +------------------------- + +The ```` element is used to view the convergence of linear GMRES +iterations in PETSc. This option can be turned on with ".true." and turned off +with ".false.". + + + *Default*: .false. + +```` Element +------------------ + +If a structured mesh is desired as a filter for a tally, it must be specified in +a separate element with the tag name ````. This element has the following +attributes/sub-elements: + + :type: + The type of structured mesh. Only "rectangular" is currently supported. + + :lower_left: + The lower-left corner of the structured mesh. If only two coordinate are + given, it is assumed that the mesh is an x-y mesh. + + :upper_right: + The upper-right corner of the structrued mesh. If only two coordinate are + given, it is assumed that the mesh is an x-y mesh. + + :dimension: + The number of mesh cells in each direction. + + :width: + The width of mesh cells in each direction. + + :energy: + 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: + 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. + + *Default*: 1.0 1.0 1.0 1.0 1.0 1.0 + + :map: + 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. + + .. note:: Only two of the following three sub-elements are needed: + ``lower_left``, ``upper_right`` and ``width``. Any combination + of two of these will yield the third. + +```` Element +------------------ + +The ```` element is used to normalize the CMFD fission source distribution +to a particular value. For example, if a fission source is calculated for a +17 x 17 lattice of pins, the fission source may be normalized to the number of +fission source regions, in this case 289. This is useful when visualizing this +distribution as the average peaking factor will be unity. This parameter will +not impact the calculation. + + *Default*: 1.0 + +```` Element +-------------------------- + +The ```` element is used to set the number of processors used +for CMFD calculation. It should be less than or equal to the number of +processors used during OpenMC. + + *Default*: 1 + +```` Element +--------------------------- + +The ```` element is used to view the convergence of power iteration. +This option can be turned on with ".true." and turned off with ".false.". + + + *Default*: .false. + +```` Element +--------------------------- + +The ```` element is used to view the balance of OpenMC tally +residuals for every coarse mesh region and energy group. This option can be +turned on with ".true." and off with ".false.". + + + *Default*: .false. + +```` Element +------------------------ + +The ```` element can be turned on with ".true." to get an +HDF5 output file of CMFD results. + + *Default*: .false. + +```` Element +---------------------------- + +The ```` element is used to view the PETSc sparse matrices +created when solving CMFD equations. These binary output files can be imported +into MATLAB using PETSc-MATLAB utilities. This option can be +turned on with ".true." and off with ".false.". + + *Default*: .false.