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 $var element = document.getElementById("moose-equation-5fcae4dc-fa14-41c5-8e58-c86698aea39f");katex.render("\\Omega", element, {displayMode:false,throwOnError:false});$ is defined as

$var element = document.getElementById("moose-equation-9660051d-2a25-4c86-b1a2-edad08466ef9");katex.render("\\underbrace{-f}_{\\textrm{BodyForce}} + \\sum_{i=1}^n \\beta_i = 0 \\in \\Omega", element, {displayMode:true,throwOnError:false});$ where $var element = document.getElementById("moose-equation-40a4d18b-93de-4d60-9ebe-7634b9a7ed79");katex.render("f", element, {displayMode:false,throwOnError:false});$ 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

$var element = document.getElementById("moose-equation-92c7ef10-9318-4dce-861e-7a0e17a402c1");katex.render("R_i(u_h) = (\\psi_i, -f) \\quad \\forall \\psi_i,", element, {displayMode:true,throwOnError:false});$ where the $var element = document.getElementById("moose-equation-32a6037b-6212-416e-a33f-815dc14cd0dc");katex.render("\\psi_i", element, {displayMode:false,throwOnError:false});$ are the test functions, and $var element = document.getElementById("moose-equation-8bec0212-ffd6-46ab-bebe-30a4b08d57d3");katex.render("u_h", element, {displayMode:false,throwOnError:false});$ are the trial solutions in the finite dimensional space $var element = document.getElementById("moose-equation-25f0987f-df06-4c1c-a557-0433c7f75e2a");katex.render("\\mathcal{S}^h", element, {displayMode:false,throwOnError:false});$ for the unknown ( $var element = document.getElementById("moose-equation-a54a69ce-cc46-40cf-843c-b8fd11d0b8f1");katex.render("u", element, {displayMode:false,throwOnError:false});$ ).

The Jacobian term for this kernel is zero: $var element = document.getElementById("moose-equation-06ba69a3-a0b9-4c81-af15-e372000ad9aa");katex.render("\\frac{\\partial R_i(u_h)}{\\partial u_j} = 0", element, {displayMode:false,throwOnError:false});$ , since it is assumed that $var element = document.getElementById("moose-equation-7f0fba18-f438-49fa-8108-1b1f417266db");katex.render("f", element, {displayMode:false,throwOnError:false});$ is not a function of the unknown $var element = document.getElementById("moose-equation-95bd9ff1-419c-48a4-8440-cd2cf65e3869");katex.render("u", element, {displayMode:false,throwOnError:false});$ .

The force is constructed through a user supplied constant $var element = document.getElementById("moose-equation-e7b94d23-2b75-4b26-a3cf-8a2321b3784d");katex.render("c", element, {displayMode:false,throwOnError:false});$ , function value evaluated at the current time and quadrature point $var element = document.getElementById("moose-equation-08b5d6e1-f214-45cb-b093-645bf79e4aec");katex.render("f", element, {displayMode:false,throwOnError:false});$ , and/or postprocessor value $var element = document.getElementById("moose-equation-c2536f44-62ab-4f09-9904-1b1b323d4535");katex.render("p", element, {displayMode:false,throwOnError:false});$ . The constant $var element = document.getElementById("moose-equation-6c7e2789-e7d4-42d9-84cd-73976bee48b5");katex.render("c", element, {displayMode:false,throwOnError:false});$ , supplied through the parameter value, may also be controlled over the course of a transient simulation with a Controls block. $var element = document.getElementById("moose-equation-75a37f05-0637-4221-ad8c-f6c88f9dd46e");katex.render("c", element, {displayMode:false,throwOnError:false});$ , $var element = document.getElementById("moose-equation-69284ee0-ae4c-499d-a31d-64e80f3a98fb");katex.render("f", element, {displayMode:false,throwOnError:false});$ , $var element = document.getElementById("moose-equation-fd630eac-1ee4-4db2-8e39-b9dcdfcc1e05");katex.render("p", element, {displayMode:false,throwOnError:false});$ are supplied through the input parameters value, function, and postprocessor respectively. Not supplying $var element = document.getElementById("moose-equation-e57be10c-6b12-4621-a480-381de1f172b3");katex.render("c", element, {displayMode:false,throwOnError:false});$ , $var element = document.getElementById("moose-equation-ba8b0922-3484-4ba4-a4c1-7ec2a861b5d2");katex.render("f", element, {displayMode:false,throwOnError:false});$ , or $var element = document.getElementById("moose-equation-235bf1a7-dcd0-4d9d-a304-866c10e2c785");katex.render("p", element, {displayMode:false,throwOnError:false});$ 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
  [../]
[]

Input Parameters

variableThe name of the variable that this residual object operates on
C++ Type:NonlinearVariableName
Unit:(no unit assumed)
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>
Unit:(no unit assumed)
Controllable:No
Description:The list of blocks (ids or names) that this object will be applied
displacementsThe displacements
C++ Type:std::vector<VariableName>
Unit:(no unit assumed)
Controllable:No
Description:The displacements
function1A function that describes the body force
Default:1
C++ Type:FunctionName
Unit:(no unit assumed)
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
Unit:(no unit assumed)
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
Unit:(no unit assumed)
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.
use_interpolated_stateFalseFor the old and older state use projected material properties interpolated at the quadrature points. To set up projection use the ProjectedStatefulMaterialStorageAction.
Default:False
C++ Type:bool
Unit:(no unit assumed)
Controllable:No
Description:For the old and older state use projected material properties interpolated at the quadrature points. To set up projection use the ProjectedStatefulMaterialStorageAction.
value1Coefficient to multiply by the body force term
Default:1
C++ Type:double
Unit:(no unit assumed)
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>
Unit:(no unit assumed)
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>
Unit:(no unit assumed)
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>
Unit:(no unit assumed)
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
Unit:(no unit assumed)
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
Unit:(no unit assumed)
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>
Unit:(no unit assumed)
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>
Unit:(no unit assumed)
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
Unit:(no unit assumed)
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
Unit:(no unit assumed)
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>
Unit:(no unit assumed)
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
Unit:(no unit assumed)
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
Unit:(no unit assumed)
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

(moose/test/tests/kernels/block_kernel/block_kernel_test.i)

[Mesh]
  file = rectangle.e
  uniform_refine = 1
[]

[Variables]
  [./u]
    order = FIRST
    family = LAGRANGE
    initial_condition = 1.0
  [../]
[]

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

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

  [./time]
    type = TimeDerivative
    variable = u
  [../]
[]

[BCs]
  [./right]
    type = DirichletBC
    variable = u
    boundary = 2
    value = 1
  [../]
[]

[Executioner]
  type = Transient
  solve_type = 'PJFNK'
  dt = 0.1
  num_steps = 10
[]

[Outputs]
  file_base = out
  exodus = true
[]

Description
Example Syntax
Input Parameters