Variables System

Description

The Variables block within an input file is utilized to define the unknowns within a system of partial differential equations. These unknowns are often referred to as nonlinear variables within documentation. The nonlinear variables defined within this block are used by Kernel objects to define the equations for a simulation.

Example

The following input file snippet demonstrates the creation of a single nonlinear variable that is used by two Kernel objects, refer to Example 2 for more details.

[Variables]
  [convected]
    order = FIRST
    family = LAGRANGE
  []
[]

[Kernels]
  [diff]
    type = Diffusion
    variable = convected
  []

  [conv]
    type = ExampleConvection
    variable = convected
    velocity = '0.0 0.0 1.0'
  []
[]
(examples/ex02_kernel/ex02.i)

Input Parameters

  • familyLAGRANGESpecifies the family of FE shape functions to use for this variable

    Default:LAGRANGE

    C++ Type:MooseEnum

    Options:LAGRANGE MONOMIAL HERMITE SCALAR HIERARCHIC CLOUGH XYZ SZABAB BERNSTEIN L2_LAGRANGE L2_HIERARCHIC NEDELEC_ONE LAGRANGE_VEC

    Description:Specifies the family of FE shape functions to use for this variable

  • initial_conditionSpecifies the initial condition for this variable

    C++ Type:double

    Options:

    Description:Specifies the initial condition for this variable

  • inactiveIf specified blocks matching these identifiers will be skipped.

    C++ Type:std::vector

    Options:

    Description:If specified blocks matching these identifiers will be skipped.

  • active__all__ If specified only the blocks named will be visited and made active

    Default:__all__

    C++ Type:std::vector

    Options:

    Description:If specified only the blocks named will be visited and made active

  • orderFIRSTSpecifies the order of the FE shape function to use for this variable (additional orders not listed are allowed)

    Default:FIRST

    C++ Type:MooseEnum

    Options:CONSTANT FIRST SECOND THIRD FOURTH

    Description:Specifies the order of the FE shape function to use for this variable (additional orders not listed are allowed)

  • blockThe block id where this variable lives

    C++ Type:std::vector

    Options:

    Description:The block id where this variable lives

Optional Parameters

  • scaling1Specifies a scaling factor to apply to this variable

    Default:1

    C++ Type:double

    Options:

    Description:Specifies a scaling factor to apply to this variable

  • 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

  • eigenFalseTrue to make this variable an eigen variable

    Default:False

    C++ Type:bool

    Options:

    Description:True to make this variable an eigen variable

Advanced Parameters

Available Subsystems

Available Actions