FeatureFloodCount

The FeatureFloodCount object is a utility that inspects solution fields looking for Connected Components) or "topologically connected regions of a solution field sharing a similar characteristic". Typically, this means a region where the solution value is higher than some threshold. This object is designed to work efficiently on a partitioned unstructured mesh with hundreds to thousands of processors.

Figure 1: The identification of a new feature.

Figure 2: Intermediate stage of identification.

Figure 3: Identification of the region complete.

Figure 4: Halo extension complete.


The algorithm for identifying portions of connected components begins by running a Flood Fill algorthim on each processor that recursively visits neighboring elements on the unstructured mesh while the connecting criteria is met. Figure 1 illustrates the identification of a new region on a processor. The dark shaded element represents an element that was identified whose variable value exceeds a given threshold. The lightly shaded elements surronding the dark element represent the current "halo" markings of the region. These halo markings always extend one neighbor beyond the currently shaded region. They are used for both the connected component algorithm and for identifying potential collisions among disjoint regions.

Figure 5: Regular grid with 6 features partitioned 3 ways.

Figure 6: Global identification of all features.


Several pieces of information are recorded on each processor including all of the marked elements, a minimum ID for a partition independent stable ordering and "overlapping elements" for stitching. Figure 5 shows a regular mesh partitioned among three processors with several regions of interest. The alpha characters represent a possible local ordering of the features. The subscript represents the processor ID. Portions of the feature data structure is serialized and sent to the rank 0 process where connection information is used to discover the global picture Figure 6.

The object is able to find and count "connected components" in any solution field or number of solution fields. A primary example would be to count "bubbles".

Input Parameters

  • variableThe variable(s) for which to find connected regions of interests, i.e. "features".

    C++ Type:std::vector

    Options:

    Description:The variable(s) for which to find connected regions of interests, i.e. "features".

Required Parameters

  • enable_var_coloringFalseInstruct the Postprocessor to populate the variable index map.

    Default:False

    C++ Type:bool

    Options:

    Description:Instruct the Postprocessor to populate the variable index map.

  • connecting_thresholdThe threshold for which an existing feature may be extended (defaults to "threshold")

    C++ Type:double

    Options:

    Description:The threshold for which an existing feature may be extended (defaults to "threshold")

  • use_less_than_threshold_comparisonTrueControls whether features are defined to be less than or greater than the threshold value.

    Default:True

    C++ Type:bool

    Options:

    Description:Controls whether features are defined to be less than or greater than the threshold value.

  • threshold0.5The threshold value for which a new feature may be started

    Default:0.5

    C++ Type:double

    Options:

    Description:The threshold value for which a new feature may be started

  • compute_var_to_feature_mapFalseInstruct the Postprocessor to compute the active vars to features map

    Default:False

    C++ Type:bool

    Options:

    Description:Instruct the Postprocessor to compute the active vars to features map

  • flood_entity_typeELEMENTALDetermines whether the flood algorithm runs on nodes or elements

    Default:ELEMENTAL

    C++ Type:MooseEnum

    Options:NODAL ELEMENTAL

    Description:Determines whether the flood algorithm runs on nodes or elements

  • execute_onTIMESTEP_ENDThe list of flag(s) indicating when this object should be executed, the available options include NONE, INITIAL, LINEAR, NONLINEAR, TIMESTEP_END, TIMESTEP_BEGIN, FINAL, CUSTOM.

    Default:TIMESTEP_END

    C++ Type:ExecFlagEnum

    Options:NONE INITIAL LINEAR NONLINEAR TIMESTEP_END TIMESTEP_BEGIN FINAL CUSTOM

    Description:The list of flag(s) indicating when this object should be executed, the available options include NONE, INITIAL, LINEAR, NONLINEAR, TIMESTEP_END, TIMESTEP_BEGIN, FINAL, CUSTOM.

  • boundaryThe list of boundary IDs from the mesh where this boundary condition applies

    C++ Type:std::vector

    Options:

    Description:The list of boundary IDs from the mesh where this boundary condition applies

  • compute_halo_mapsFalseInstruct the Postprocessor to communicate proper halo information to all ranks

    Default:False

    C++ Type:bool

    Options:

    Description:Instruct the Postprocessor to communicate proper halo information to all ranks

Optional Parameters

  • enableTrueSet the enabled status of the MooseObject.

    Default:True

    C++ Type:bool

    Options:

    Description:Set the enabled status of the MooseObject.

  • use_displaced_meshFalseWhether or not this object should use the displaced mesh for computation. Note that in the case this is true but no displacements are provided in the Mesh block the undisplaced mesh will still be used.

    Default:False

    C++ Type:bool

    Options:

    Description:Whether or not this object should use the displaced mesh for computation. Note that in the case this is true but no displacements are provided in the Mesh block the undisplaced mesh will still be used.

  • outputsVector of output names were you would like to restrict the output of variables(s) associated with this object

    C++ Type:std::vector

    Options:

    Description:Vector of output names were you would like to restrict the output of variables(s) associated with this object

  • use_single_mapTrueDetermine whether information is tracked per coupled variable or consolidated into one (default: true)

    Default:True

    C++ Type:bool

    Options:

    Description:Determine whether information is tracked per coupled variable or consolidated into one (default: true)

  • control_tagsAdds user-defined labels for accessing object parameters via control logic.

    C++ Type:std::vector

    Options:

    Description:Adds user-defined labels for accessing object parameters via control logic.

  • allow_duplicate_execution_on_initialFalseIn the case where this UserObject is depended upon by an initial condition, allow it to be executed twice during the initial setup (once before the IC and again after mesh adaptivity (if applicable).

    Default:False

    C++ Type:bool

    Options:

    Description:In the case where this UserObject is depended upon by an initial condition, allow it to be executed twice during the initial setup (once before the IC and again after mesh adaptivity (if applicable).

  • condense_map_infoFalseDetermines whether we condense all the node values when in multimap mode (default: false)

    Default:False

    C++ Type:bool

    Options:

    Description:Determines whether we condense all the node values when in multimap mode (default: false)

  • use_global_numberingTrueDetermine whether or not global numbers are used to label features on multiple maps (default: true)

    Default:True

    C++ Type:bool

    Options:

    Description:Determine whether or not global numbers are used to label features on multiple maps (default: true)

  • force_preauxFalseForces the GeneralUserObject to be executed in PREAUX

    Default:False

    C++ Type:bool

    Options:

    Description:Forces the GeneralUserObject to be executed in PREAUX

Advanced Parameters

Input Files

Child Objects