# FunctionDirichletBC

Imposes the essential boundary condition , where is a (possibly) time and space-dependent MOOSE Function.

## Description

FunctionDirichletBC is a generalization of DirichletBC which imposes a possibly temporally- and spatially-dependent value defined by a MOOSE Function object on a particular set of degrees of freedom (DOFs) defined by the boundary parameter. That is, for a PDE of the form

(1)

where is the domain, and is its boundary, a FunctionDirichletBC object can be used to impose the condition (2) if the function is well-defined for . In this case, the function parameter corresponds to a MOOSE Function object which represents the mathematical function , and the user must define one or more sidesets corresponding to the boundary subset via the boundary parameter.

## Example Input Syntax

[BCs]
active = 'all'

# Boundary Condition System
[./all]
type = FunctionDirichletBC
variable = u
boundary = '1 2'
function = bc_func
[../]
[]

(test/tests/bcs/function_dirichlet_bc/function_dirichlet_bc_test.i)

## Input Parameters

• functionThe forcing function.

C++ Type:FunctionName

Options:

Description:The forcing function.

• 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

• 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

### Required Parameters

• 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.)

• displacementsThe displacements

C++ Type:std::vector

Options:

Description:The displacements

• 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.)

### 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.

• seed0The seed for the master random number generator

Default:0

C++ Type:unsigned int

Options:

Description:The seed for the master random number generator

• 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

• 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.

• 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

• 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

• 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