FVNeumannBC

Neumann boundary condition for finite volume method.

Overview

A FVNeumannBC may be used to specify a diffusive or an advective flux. For example, to specify a flux boundary condition in the following diffusion problem, a FVNeumannBC with a constant value of $var element = document.getElementById("moose-equation-3d90f868-52d7-4858-83d3-ff0263276e1c");katex.render("g", element, {displayMode:false,throwOnError:false});$ may be used.

$var element = document.getElementById("moose-equation-ba642a9f-f56e-4830-9a9c-110ab86370d5");katex.render("\\begin{aligned} -\\nabla^2 u(\\mathbf{M}) &= f(\\mathbf{M}) && \\forall \\mathbf{M} \\in \\Omega & (1)\\\\ \\frac{\\partial u}{\\partial n}(\\mathbf{M}) &= g && \\forall \\mathbf{M} \\in \\partial \\Omega_N & (2) \\\\ u(\\mathbf{M}) &= 1 && \\forall \\mathbf{M} \\in \\partial \\Omega_D & (3) \\end{aligned}", element, {displayMode:true,throwOnError:false});$

where $var element = document.getElementById("moose-equation-293f65db-17a0-40df-9bf4-eab6c894112e");katex.render("\\Omega \\subset \\mathbb{R}^n", element, {displayMode:false,throwOnError:false});$ is the domain, $var element = document.getElementById("moose-equation-c94a81bd-e4de-4cb5-9d4a-2fd5476f7549");katex.render("\\partial \\Omega = \\partial \\Omega_D \\cup \\partial \\Omega_N", element, {displayMode:false,throwOnError:false});$ is its boundary, and $var element = document.getElementById("moose-equation-63f11a11-0242-499d-8d84-1b4664ece4ae");katex.render("\\mathbf{M}", element, {displayMode:false,throwOnError:false});$ is a point on the domain or its boundary. In this case, a FVNeumannBC object is used to impose the condition (2) on the subset of the boundary denoted by $var element = document.getElementById("moose-equation-201209c4-0792-491f-8646-f933db5ed3c1");katex.render("\\partial \\Omega_D", element, {displayMode:false,throwOnError:false});$ . In this case, the value field corresponds to the constant $var element = document.getElementById("moose-equation-74d8f30e-885b-44b4-98f1-58117466427f");katex.render("g", element, {displayMode:false,throwOnError:false});$ , and the user must define one or more sidesets corresponding to the boundary $var element = document.getElementById("moose-equation-bae86bed-a2bf-4f41-8376-c25dcd2662c9");katex.render("\\partial \\Omega_D", element, {displayMode:false,throwOnError:false});$ to pass to the boundary argument. For this particular problem, an additional boundary condition, for example a FVDirichletBC as in (3) would also be necessary to remove the nullspace.

Likewise, to specify an advective flux of constant value $var element = document.getElementById("moose-equation-b715c3c3-e148-4717-b6c5-e63d0706de8d");katex.render("g", element, {displayMode:false,throwOnError:false});$ in a 1D advection problem with an advective velocity $var element = document.getElementById("moose-equation-5e249b2f-6b9a-485e-b542-882c683f4260");katex.render("v", element, {displayMode:false,throwOnError:false});$ :

$var element = document.getElementById("moose-equation-834cabed-6564-402d-891d-4966dfaa73c8");katex.render("\\begin{aligned} \\frac{\\partial u}{\\partial t}(\\mathbf{M}) + v \\frac{\\partial u}{\\partial x}(\\mathbf{M}) &= 0 && \\forall \\mathbf{M} \\in \\Omega & (1)\\\\ v u(\\mathbf{M}) &= g v && \\forall \\mathbf{M} \\in \\partial \\Omega & (2) \\end{aligned}", element, {displayMode:true,throwOnError:false});$

The advective flux, the value to specify to the boundary condition (2), is $var element = document.getElementById("moose-equation-26bac3e2-4b82-4d98-980b-a814b7a8ec55");katex.render("g v", element, {displayMode:false,throwOnError:false});$ .

Modeling a multi-dimensional problem will require a FVNeumannBC per component.

note

When using the Navier Stokes module, FVNeumannBC may not be available for use with velocity and pressure, as additional information is required on either the gradient or direction of these variables to model fully developed flow for example. Specific boundary conditions are provided, see for example INSFVOutletPressureBC.

Input Parameters

boundaryThe list of boundary IDs from the mesh where this object applies
C++ Type:std::vector<BoundaryName>
Unit:(no unit assumed)
Controllable:No
Description:The list of boundary IDs from the mesh where this object applies
variableThe name of the variable that this boundary condition applies to
C++ Type:NonlinearVariableName
Unit:(no unit assumed)
Controllable:No
Description:The name of the variable that this boundary condition applies to

Required Parameters

displacementsThe displacements
C++ Type:std::vector<VariableName>
Unit:(no unit assumed)
Controllable:No
Description:The displacements
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.
value0The value of the flux crossing the boundary.
Default:0
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:The value of the flux crossing the boundary.

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.
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
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

Overview
Input Parameters