LowerBoundNodalKernel

Used to prevent a coupled variable from going below a lower bound

Description

LowerBoundNodalKernel is meant to be used to impose a lower bound on a coupled variable v. The variable specified by the variable parameter is a Lagrange multiplier. It should have an order equivalent to that of the coupled variable v. The lower bound is specified using the lower_bound parameter. By default it is 0. An optional parameter is exclude_boundaries which can be used to specify boundary nodes where the LowerBoundNodalKernel should not be applied. This can be useful for avoiding singularities in the preconditioning matrix that can arise when a constraint is active in the same place that another constraint (like a DirichletBC is also active).

Example Syntax

[NodalKernels]
  [positive_constraint]
    type = LowerBoundNodalKernel
    variable = lm
    v = u
    exclude_boundaries = 'left right'
  []
  [forces]
    type = CoupledForceNodalKernel
    variable = u
    v = lm
  []
[]
(../moose/test/tests/nodalkernels/constraint_enforcement/lower-bound.i)

Input Parameters

  • vThe coupled variable we require to be greater than the lower bound

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

    Controllable:No

    Description:The coupled variable we require to be greater than the lower bound

  • variableThe name of the variable that this residual object operates on

    C++ Type:NonlinearVariableName

    Controllable:No

    Description:The name of the variable that this residual object operates on

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

  • exclude_boundariesBoundaries on which not to execute the NodalKernel. This can be useful for avoiding singuarility in the matrix in case a constraint is active in the same place that a DirichletBC is set

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

    Controllable:No

    Description:Boundaries on which not to execute the NodalKernel. This can be useful for avoiding singuarility in the matrix in case a constraint is active in the same place that a DirichletBC is set

  • lower_bound0The lower bound on the coupled variable

    Default:0

    C++ Type:double

    Controllable:No

    Description:The lower bound on the coupled variable

Optional Parameters

  • absolute_value_vector_tagsThe tags for the vectors this residual object should fill with the absolute value of the residual contribution

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

    Controllable:No

    Description:The tags for the vectors this residual object should fill with the absolute value of the residual contribution

  • extra_matrix_tagsThe extra tags for the matrices this Kernel should fill

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

    Controllable:No

    Description:The extra tags for the matrices this Kernel should fill

  • extra_vector_tagsThe extra tags for the vectors this Kernel should fill

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

    Controllable:No

    Description:The extra tags for the vectors this Kernel should fill

  • matrix_tagssystemThe tag for the matrices this Kernel should fill

    Default:system

    C++ Type:MultiMooseEnum

    Options:nontime, system

    Controllable:No

    Description:The tag for the matrices this Kernel should fill

  • vector_tagsnontimeThe tag for the vectors this Kernel should fill

    Default:nontime

    C++ Type:MultiMooseEnum

    Options:nontime, time

    Controllable:No

    Description:The tag for the vectors this Kernel should fill

Tagging 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.

  • diag_save_inThe name of auxiliary variables to save this BC's diagonal jacobian contributions to. Everything about that variable must match everything about this variable (the type, what blocks it's on, etc.)

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

    Controllable:No

    Description:The name of auxiliary variables to save this BC's diagonal jacobian contributions to. Everything about that variable must match everything about this variable (the type, what blocks it's on, etc.)

  • enableTrueSet the enabled status of the MooseObject.

    Default:True

    C++ Type:bool

    Controllable:Yes

    Description:Set the enabled status of the MooseObject.

  • implicitTrueDetermines whether this object is calculated using an implicit or explicit form

    Default:True

    C++ Type:bool

    Controllable:No

    Description:Determines whether this object is calculated using an implicit or explicit form

  • save_inThe name of auxiliary variables to save this BC's residual contributions to. Everything about that variable must match everything about this variable (the type, what blocks it's on, etc.)

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

    Controllable:No

    Description:The name of auxiliary variables to save this BC's residual contributions to. Everything about that variable must match everything about this variable (the type, what blocks it's on, etc.)

  • 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