DirichletBC

Imposes the essential boundary condition , where is a constant, controllable value.

Description

DirichletBC is the simplest type of NodalBC, and is used for imposing so-called "essential" boundary conditions on systems of partial differential equations (PDEs). Such boundary conditions force a particular set of degrees of freedom (DOFs) defined by the boundary parameter to take on a single, controllable value. This class is appropriate to use for PDEs of the form

where is the domain, and is its boundary. In this case, a DirichletBC object is used to impose the condition (2) on the subset of the boundary denoted by . In this case, the value corresponds to the constant , and the user must define one or more sidesets corresponding to the boundary subset .

Preset boundary conditions

With the parameter preset = true, the value of the boundary condition is applied before the solve begins. With preset = false, the boundary condition is only enforced as the solve progresses. In most situations, presetting the boundary condition is better.

The default behavior of the preset parameter is determined by the flag use_legacy_dirichlet_bc in the application. Change this flag to false to switch your application to the preferred behavior (setting preset = true as the default).

Example Input Syntax

  [./right_v]
    type = DirichletBC
    variable = v
    boundary = 2
    value = 3
  [../]
(test/tests/bcs/matched_value_bc/matched_value_bc_test.i)

Input Parameters

  • 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

  • valueValue of the BC

    C++ Type:double

    Options:

    Description:Value of the BC

  • variableThe name of the variable that this boundary condition applies to

    C++ Type:NonlinearVariableName

    Options:

    Description:The name of the variable that this boundary condition applies to

Required Parameters

  • 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

    Options:

    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.)

  • displacementsThe displacements

    C++ Type:std::vector

    Options:

    Description:The displacements

  • presetTrueWhether or not to preset the BC (apply the value before the solve begins). Note that the default value of this parameter is handled by the use_legacy_dirichlet_bc parameter on the MooseApp.

    Default:True

    C++ Type:bool

    Options:

    Description:Whether or not to preset the BC (apply the value before the solve begins). Note that the default value of this parameter is handled by the use_legacy_dirichlet_bc parameter on the MooseApp.

  • 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

    Options:

    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.)

Optional Parameters

  • 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.

  • enableTrueSet the enabled status of the MooseObject.

    Default:True

    C++ Type:bool

    Options:

    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

    Options:

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

  • seed0The seed for the master random number generator

    Default:0

    C++ Type:unsigned int

    Options:

    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

    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.

Advanced Parameters

  • extra_matrix_tagsThe extra tags for the matrices this Kernel should fill

    C++ Type:std::vector

    Options:

    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

    Options:

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

  • matrix_tagssystem timeThe tag for the matrices this Kernel should fill

    Default:system time

    C++ Type:MultiMooseEnum

    Options:nontime system time

    Description:The tag for the matrices this Kernel should fill

  • vector_tagsresidualThe tag for the vectors this Kernel should fill

    Default:residual

    C++ Type:MultiMooseEnum

    Options:nontime time residual

    Description:The tag for the vectors this Kernel should fill

Tagging Parameters

Input Files

Child Objects