BodyForce

Description

BodyForce implements a force term in momentum transport or structural mechanics or a source term in species/mass transport. The strong form, given a domain is defined as

where is the source term (negative if a sink) and the second term on the left hand side represents the strong forms of other kernels. The BodyForce weak form, in inner-product notation, is defined as

where the are the test functions, and are the trial solutions in the finite dimensional space for the unknown ().

The Jacobian term for this kernel is zero: , since it is assumed that is not** a function of the unknown .

The force is constructed through a user supplied constant , function value evaluated at the current time and quadrature point , and/or postprocessor value . The constant , supplied through the parameter value, may also be controlled over the course of a transient simulation with a Controls block. , , are supplied through the input parameters value, function, and postprocessor respectively. Not supplying , , or through its corresponding parameter is equivalent to setting its value to unity.

Example Syntax

The case below demonstrates the use of BodyForce where the force term is supplied based upon a function form:

[Kernels]
  [./diff]
    type = Diffusion
    variable = u
  [../]

  [./body_force]
    type = BodyForce
    variable = u
    block = 1
    value = 10
    function = 'x+y'
  [../]

  [./time]
    type = TimeDerivative
    variable = u
  [../]
[]
(../moose/test/tests/kernels/block_kernel/block_kernel_test.i)

Input Parameters

  • 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

  • displacementsThe displacements

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

    Controllable:No

    Description:The displacements

  • function1A function that describes the body force

    Default:1

    C++ Type:FunctionName

    Controllable:No

    Description:A function that describes the body force

  • postprocessor1A postprocessor whose value is multiplied by the body force

    Default:1

    C++ Type:PostprocessorName

    Controllable:No

    Description:A postprocessor whose value is multiplied by the body force

  • 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.

  • value1Coefficient to multiply by the body force term

    Default:1

    C++ Type:double

    Controllable:Yes

    Description:Coefficient to multiply by the body force term

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 Kernel'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 Kernel'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 Kernel'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 Kernel'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