FVTwoVarContinuityConstraint

Forces two variables to be equal on an interface for the finite volume method.

The constraint is enforced using a Lagrange multiplier variable.

note

Lagrange multipliers do not contribute to the diagonal of the residual, which can hurt numerical convergence for some linear solvers. For the lu (sub-)preconditioner, make sure to use a NONZERO (sub_)pc_factor_shift_type.

note

kernel_coverage_check, a parameter in the [Problem] block, should be set to false, as the Lagrange multiplier variable is a variable that is not found on any block, only on the interface.

Example input file syntax

In this example, we solve two diffusion problems in two adjacent subdomains and force continuity at the interface, recovering the expected solution of a diffusion problem spanning the entire domain.

[interface]
  type = FVTwoVarContinuityConstraint
  variable1 = u
  variable2 = v
  boundary = 'primary_interface'
  subdomain1 = '0'
  subdomain2 = '1'
  lambda = 'lambda'
[]

Input Parameters

boundaryThe list of boundary IDs from the mesh where this object applies
C++ Type:std::vector<BoundaryName>
Controllable:No
Description:The list of boundary IDs from the mesh where this object applies
lambdaThe name of the scalar lagrange multiplier
C++ Type:std::vector<VariableName>
Controllable:No
Description:The name of the scalar lagrange multiplier
subdomain1The subdomains on the 1st side of the boundary.
C++ Type:std::vector<SubdomainName>
Controllable:No
Description:The subdomains on the 1st side of the boundary.
subdomain2The subdomains on the 2nd side of the boundary.
C++ Type:std::vector<SubdomainName>
Controllable:No
Description:The subdomains on the 2nd side of the boundary.
variable1The name of the first variable that this interface kernel applies to
C++ Type:NonlinearVariableName
Controllable:No
Description:The name of the first variable that this interface kernel applies to

Required Parameters

displacementsThe displacements
C++ Type:std::vector<VariableName>
Controllable:No
Description:The displacements
execute_onLINEARThe list of flag(s) indicating when this object should be executed, the available options include NONE, INITIAL, LINEAR, NONLINEAR, TIMESTEP_END, TIMESTEP_BEGIN, MULTIAPP_FIXED_POINT_END, MULTIAPP_FIXED_POINT_BEGIN, FINAL, CUSTOM, ALWAYS.
Default:LINEAR
C++ Type:ExecFlagEnum
Options:NONE, INITIAL, LINEAR, NONLINEAR, TIMESTEP_END, TIMESTEP_BEGIN, MULTIAPP_FIXED_POINT_END, MULTIAPP_FIXED_POINT_BEGIN, FINAL, CUSTOM, ALWAYS
Controllable:No
Description:The list of flag(s) indicating when this object should be executed, the available options include NONE, INITIAL, LINEAR, NONLINEAR, TIMESTEP_END, TIMESTEP_BEGIN, MULTIAPP_FIXED_POINT_END, MULTIAPP_FIXED_POINT_BEGIN, FINAL, CUSTOM, ALWAYS.
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.
variable2The name of the second variable that this interface kernel applies to. If not supplied, variable1 will be used.
C++ Type:NonlinearVariableName
Controllable:No
Description:The name of the second variable that this interface kernel applies to. If not supplied, variable1 will be used.

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.
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
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

ghost_layers1The number of layers of elements to ghost.
Default:1
C++ Type:unsigned short
Controllable:No
Description:The number of layers of elements to ghost.
use_point_neighborsFalseWhether to use point neighbors, which introduces additional ghosting to that used for simple face neighbors.
Default:False
C++ Type:bool
Controllable:No
Description:Whether to use point neighbors, which introduces additional ghosting to that used for simple face neighbors.

Parallel Ghosting Parameters

(moose/test/tests/fviks/continuity/test.i)

[Mesh]
  [gen]
    type = GeneratedMeshGenerator
    dim = 1
    nx = 20
    xmax = 2
  []
  [subdomain1]
    input = gen
    type = SubdomainBoundingBoxGenerator
    bottom_left = '1.0 0 0'
    block_id = 1
    top_right = '2.0 1.0 0'
  []
  [interface_primary_side]
    input = subdomain1
    type = SideSetsBetweenSubdomainsGenerator
    primary_block = '0'
    paired_block = '1'
    new_boundary = 'primary_interface'
  []
[]

[GlobalParams]
  # retain behavior at time of test creation
  two_term_boundary_expansion = false
[]

[Variables]
  [u]
    type = MooseVariableFVReal
    block = 0
    initial_condition = 0.5
  []
  [v]
    type = MooseVariableFVReal
    block = 1
    initial_condition = 0.5
  []
  [lambda]
    type = MooseVariableScalar
  []
[]

[Problem]
  kernel_coverage_check = false
[]

[FVKernels]
  [diff_left]
    type = FVDiffusion
    variable = u
    coeff = 'left'
    block = 0
  []
  [diff_right]
    type = FVDiffusion
    variable = v
    coeff = 'right'
    block = 1
  []
[]

[FVInterfaceKernels]
  [interface]
    type = FVTwoVarContinuityConstraint
    variable1 = u
    variable2 = v
    boundary = 'primary_interface'
    subdomain1 = '0'
    subdomain2 = '1'
    lambda = 'lambda'
  []
[]

[FVBCs]
  [left]
    type = FVDirichletBC
    variable = u
    boundary = 'left'
    value = 1
  []
  [v_left]
    type = FVDirichletBC
    variable = v
    boundary = 'right'
    value = 0
  []
[]

[Materials]
  [block0]
    type = ADGenericFunctorMaterial
    block = '0'
    prop_names = 'left'
    prop_values = '1'
  []
  [block1]
    type = ADGenericFunctorMaterial
    block = '1'
    prop_names = 'right'
    prop_values = '1'
  []
[]

[Preconditioning]
  [smp]
    type = SMP
    full = true
  []
[]

[Executioner]
  type = Steady
  solve_type = NEWTON
  petsc_options_iname = '-pc_type -sub_pc_type -sub_pc_factor_shift_type'
  petsc_options_value = 'asm lu NONZERO'
[]

[Outputs]
  exodus = true
[]