VariableGradientComponent

Creates a field consisting of one component of the gradient of a coupled variable.

The result of this operation is stored in an auxiliary variable: variable. The analysis of gradients is useful to examine a solution or the adequacy of a mesh discretization.

commentnote

AuxVariables currently do not contain the Automatic Differentiation information about the derivatives. Using this object in the solve, to compute a material property for example, will lead to an imperfect Jacobian which can impact convergence.

commentnote

VariableGradientComponent may only be applied to elemental variables, and only considers the gradient within an element. For example, the reported gradient of a CONSTANT MONOMIAL is identically zero.

Example Input File Syntax

In this example, u is the (linear) solution of a 2D diffusion equation with no source term. We compute the two gradient components using the AuxKernels below, which each store a gradient component in a separate auxiliary variable. We can then examine the gradient of u, for example to decide to use a finer mesh in a given direction if the corresponding gradient is not well resolved.

[AuxKernels]
  [./grad_u_x_aux]
    type = VariableGradientComponent
    variable = grad_u_x
    component = x
    gradient_variable = u
  [../]
  [./grad_u_y_aux]
    type = VariableGradientComponent
    variable = grad_u_y
    component = y
    gradient_variable = u
  [../]
[]
(../moose/test/tests/auxkernels/grad_component/grad_component.i)

Input Parameters

  • gradient_variableThe variable from which to compute the gradient component

    C++ Type:std::vector<VariableName>

    Controllable:No

    Description:The variable from which to compute the gradient component

  • variableThe name of the variable that this object applies to

    C++ Type:AuxVariableName

    Controllable:No

    Description:The name of the variable that this object applies to

Required Parameters

  • blockThe list of blocks (ids or names) that this object will be applied

    C++ Type:std::vector<SubdomainName>

    Controllable:No

    Description:The list of blocks (ids or names) that this object will be applied

  • boundaryThe list of boundaries (ids or names) from the mesh where this object applies

    C++ Type:std::vector<BoundaryName>

    Controllable:No

    Description:The list of boundaries (ids or names) from the mesh where this object applies

  • check_boundary_restrictedTrueWhether to check for multiple element sides on the boundary in the case of a boundary restricted, element aux variable. Setting this to false will allow contribution to a single element's elemental value(s) from multiple boundary sides on the same element (example: when the restricted boundary exists on two or more sides of an element, such as at a corner of a mesh

    Default:True

    C++ Type:bool

    Controllable:No

    Description:Whether to check for multiple element sides on the boundary in the case of a boundary restricted, element aux variable. Setting this to false will allow contribution to a single element's elemental value(s) from multiple boundary sides on the same element (example: when the restricted boundary exists on two or more sides of an element, such as at a corner of a mesh

  • componentThe gradient component to compute

    C++ Type:MooseEnum

    Options:x, y, z

    Controllable:No

    Description:The gradient component to compute

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

    Default:LINEAR TIMESTEP_END

    C++ Type:ExecFlagEnum

    Options:NONE, INITIAL, LINEAR, NONLINEAR, TIMESTEP_END, TIMESTEP_BEGIN, MULTIAPP_FIXED_POINT_END, MULTIAPP_FIXED_POINT_BEGIN, FINAL, CUSTOM, ALWAYS, PRE_DISPLACE

    Controllable:No

    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, MULTIAPP_FIXED_POINT_END, MULTIAPP_FIXED_POINT_BEGIN, FINAL, CUSTOM, ALWAYS, PRE_DISPLACE.

  • prop_getter_suffixAn optional suffix parameter that can be appended to any attempt to retrieve/get material properties. The suffix will be prepended with a '_' character.

    C++ Type:MaterialPropertyName

    Controllable:No

    Description:An optional suffix parameter that can be appended to any attempt to retrieve/get material properties. The suffix will be prepended with a '_' character.

Optional Parameters

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

    C++ Type:std::vector<std::string>

    Controllable:No

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

  • enableTrueSet the enabled status of the MooseObject.

    Default:True

    C++ Type:bool

    Controllable:Yes

    Description:Set the enabled status of the MooseObject.

  • seed0The seed for the master random number generator

    Default:0

    C++ Type:unsigned int

    Controllable:No

    Description:The seed for the master random number generator

  • 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

    Controllable:No

    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.

Advanced Parameters