Input File Structure

Basic Syntax

The input file used by BlackBear (or any MOOSE application) is broken into sections or blocks identified with square brackets. The type of input block is placed in the opening brackets, and empty brackets mark the end of the block.


[BlockName]
    <block lines and subblocks>
[]

Each block may contain an arbitrary number of line commands to define parameters related to that block. They can also optionally contain one or more subblocks, which may in turn contain their own nested subblocks. Subblocks are opened and closed with the following syntax:


[./subblock_name]
    <line commands>
[../]

Note that all subblocks contained within a given block must have unique names (within the opening [] brackets).

Parameters are defined with line commands, and are given as key/value pairs separated by an equals sign (=). They specify parameters to be used by the object being described. The key is a string (no whitespace), and the value may be a string, an integer, a real number, or a list of strings, integers, or real numbers. Lists are given in single quotes and are separated by whitespace.

The following are examples of line commands for a single parameter and for a list of parameters:


single_parameter = 2.3
list_of_parameters = '1.0 2.3 3.7'

Blocks and subblocks at any level can contain line commands, which must be appropriate for the scope of the block containing them. Most of the time, blocks are used to create instances of MOOSE objects, and contain a type = `` parameter to specify the type of MOOSE object to be created. The name of the MOOSE object specified in the parameter corresponds to the name of the class in the C++ source code.

Each object type has a unique set of input parameters that are valid for specifying the behavior of that object. Some parameters are required, and some are optional, and revert to default behavior if they are not specified. An error message is generated if a line command does not apply within the scope in which it is provided. Repeating a line within a block also results in an error.

In this document, line commands are shown with the keyword, an equal sign, and, in angle brackets, the value. If a default value exists for that line command, it is shown in parentheses.

In the initial description of a block, line commands common to all subblocks will be described. Those line commands are then omitted from the description of the subblocks but are nonetheless valid line commands for those subblocks.

The name of a subblock ([./<name>]) is arbitrary. However, these names should be chosen to be meaningful because they can be used to refer to those entities elsewhere in the input file. Not every created entity is referenced elsewhere, but a name must be created for every entity regardless.

Summary of MOOSE Object Types

MOOSE is an objected-oriented system with well-defined interfaces for applications to define their own physics-specific code modules. The following is a listing of the major types of MOOSE objects used by BlackBear:

  • Variable

  • Kernel

  • AuxVariable

  • AuxKernel

  • Material

  • BoundaryCondition

  • Function

  • Postprocessor

  • VectorPostprocessor

  • Constraint

  • Damper

Specialized versions of these object types are implemented to provide the functionality needed to model physics of interest for BlackBear.

BlackBear Syntax Page

A complete listing of all input syntax options in MOOSE is available on the MOOSE Documentation page. See the section on Input File Documentation. Note also that you can run


blackbear-opt --dump

to get a list of valid input options for BlackBear.

Units

BlackBear can be run using any unit system preferred by the user. Empirical models within BlackBear that depend on a specific unit system are noted in this documentation.