UpperBoundNodalKernel

Used to prevent a coupled variable from going above a upper bound

Description

UpperBoundNodalKernel is meant to be used to impose a upper bound on a coupled variable v. The variable specified by the variable parameter is a Lagrange multiplier. It should have an order equivalent to that of the coupled variable v. The upper bound is specified using the upper_bound parameter. By default it is 0. An optional parameter is exclude_boundaries which can be used to specify boundary nodes where the UpperBoundNodalKernel should not be applied. This can be useful for avoiding singularities in the preconditioning matrix that can arise when a constraint is active in the same place that another constraint (like a DirichletBC is also active).

Example Syntax

[NodalKernels]
  [positive_constraint]
    type = UpperBoundNodalKernel
    variable = lm
    v = u
    exclude_boundaries = 'left right'
    upper_bound = 10
  []
  [forces]
    type = CoupledForceNodalKernel
    variable = u
    v = lm
    coef = -1
  []
[]

/opt/civet/build_0/moose/test/tests/nodalkernels/constraint_enforcement/upper-bound.i

l=10
nx=100
num_steps=10

[Mesh]
  type = GeneratedMesh
  dim = 1
  xmax = ${l}
  nx = ${nx}
[]

[Variables]
  [u]
  []
  [lm]
  []
[]

[ICs]
  [u]
    type = FunctionIC
    variable = u
    function = '${l} - x'
  []
[]

[Kernels]
  [time]
    type = TimeDerivative
    variable = u
  []
  [diff]
    type = Diffusion
    variable = u
  []
  [ffn]
    type = BodyForce
    variable = u
    function = '1'
  []
[]

[NodalKernels]
  [positive_constraint]
    type = UpperBoundNodalKernel
    variable = lm
    v = u
    exclude_boundaries = 'left right'
    upper_bound = 10
  []
  [forces]
    type = CoupledForceNodalKernel
    variable = u
    v = lm
    coef = -1
  []
[]

[BCs]
  [left]
    type = DirichletBC
    boundary = left
    value = ${l}
    variable = u
  []
  [right]
    type = DirichletBC
    boundary = right
    value = 0
    variable = u
  []
[]

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

[Executioner]
  type = Transient
  num_steps = ${num_steps}
  solve_type = NEWTON
  dtmin = 1
  petsc_options_iname = '-snes_max_linear_solve_fail -ksp_max_it -pc_type -sub_pc_factor_levels -snes_linesearch_type'
  petsc_options_value = '0                           30          asm      16                    basic'
[]

[Outputs]
  exodus = true
  [csv]
    type = CSV
    execute_on = 'nonlinear timestep_end'
  []
  [dof]
    type = DOFMap
    execute_on = 'initial'
  []
[]

[Debug]
  show_var_residual_norms = true
[]

[Postprocessors]
  [active_lm]
    type = GreaterThanLessThanPostprocessor
    variable = lm
    execute_on = 'nonlinear timestep_end'
    value = 1e-8
  []
  [violations]
    type = GreaterThanLessThanPostprocessor
    variable = u
    execute_on = 'nonlinear timestep_end'
    value = ${fparse 10+1e-8}
    comparator = 'greater'
  []
[]

Input Parameters

vThe coupled variable we require to be greater than the upper bound
C++ Type:std::vector
Options:
Description:The coupled variable we require to be greater than the upper bound
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

Required Parameters

blockThe list of block ids (SubdomainID) that this object will be applied
C++ Type:std::vector
Options:
Description:The list of block ids (SubdomainID) that this object will be applied
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
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.)
exclude_boundariesBoundaries on which not to execute the NodalKernel. This can be useful for avoiding singuarility in the matrix in case a constraint is active in the same place that a DirichletBC is set
C++ Type:std::vector
Options:
Description:Boundaries on which not to execute the NodalKernel. This can be useful for avoiding singuarility in the matrix in case a constraint is active in the same place that a DirichletBC is set
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.)
upper_bound0The upper bound on the coupled variable
Default:0
C++ Type:double
Options:
Description:The upper bound on the coupled variable

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.
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
seed0The seed for the master random number generator
Default:0
C++ Type:unsigned int
Options:
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
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.

Advanced Parameters

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
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_tagssystemThe tag for the matrices this Kernel should fill
Default:system
C++ Type:MultiMooseEnum
Options:nontime system
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
Description:The tag for the vectors this Kernel should fill

Tagging Parameters

Input Files

test/tests/nodalkernels/constraint_enforcement/upper-bound.i
test/tests/nodalkernels/constraint_enforcement/upper-and-lower-bound.i

test/tests/nodalkernels/constraint_enforcement/upper-bound.i

l=10
nx=100
num_steps=10

[Mesh]
  type = GeneratedMesh
  dim = 1
  xmax = ${l}
  nx = ${nx}
[]

[Variables]
  [u]
  []
  [lm]
  []
[]

[ICs]
  [u]
    type = FunctionIC
    variable = u
    function = '${l} - x'
  []
[]

[Kernels]
  [time]
    type = TimeDerivative
    variable = u
  []
  [diff]
    type = Diffusion
    variable = u
  []
  [ffn]
    type = BodyForce
    variable = u
    function = '1'
  []
[]

[NodalKernels]
  [positive_constraint]
    type = UpperBoundNodalKernel
    variable = lm
    v = u
    exclude_boundaries = 'left right'
    upper_bound = 10
  []
  [forces]
    type = CoupledForceNodalKernel
    variable = u
    v = lm
    coef = -1
  []
[]


[BCs]
  [left]
    type = DirichletBC
    boundary = left
    value = ${l}
    variable = u
  []
  [right]
    type = DirichletBC
    boundary = right
    value = 0
    variable = u
  []
[]

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

[Executioner]
  type = Transient
  num_steps = ${num_steps}
  solve_type = NEWTON
  dtmin = 1
  petsc_options_iname = '-snes_max_linear_solve_fail -ksp_max_it -pc_type -sub_pc_factor_levels -snes_linesearch_type'
  petsc_options_value = '0                           30          asm      16                    basic'
[]

[Outputs]
  exodus = true
  [csv]
    type = CSV
    execute_on = 'nonlinear timestep_end'
  []
  [dof]
    type = DOFMap
    execute_on = 'initial'
  []
[]

[Debug]
  show_var_residual_norms = true
[]

[Postprocessors]
  [active_lm]
    type = GreaterThanLessThanPostprocessor
    variable = lm
    execute_on = 'nonlinear timestep_end'
    value = 1e-8
  []
  [violations]
    type = GreaterThanLessThanPostprocessor
    variable = u
    execute_on = 'nonlinear timestep_end'
    value = ${fparse 10+1e-8}
    comparator = 'greater'
  []
[]

test/tests/nodalkernels/constraint_enforcement/upper-and-lower-bound.i

l=10
nx=100
num_steps=10

[Mesh]
  type = GeneratedMesh
  dim = 1
  xmax = ${l}
  nx = ${nx}
[]

[Variables]
  [u]
  []
  [lm_upper]
  []
  [lm_lower]
  []
[]

[ICs]
  [u]
    type = FunctionIC
    variable = u
    function = 'x'
  []
[]

[Kernels]
  [time]
    type = TimeDerivative
    variable = u
  []
  [diff]
    type = Diffusion
    variable = u
  []
  [ffn]
    type = BodyForce
    variable = u
    function = 'if(x<5,-1,1)'
  []
[]

[NodalKernels]
  [upper_bound]
    type = UpperBoundNodalKernel
    variable = lm_upper
    v = u
    exclude_boundaries = 'left right'
    upper_bound = 10
  []
  [forces_from_upper]
    type = CoupledForceNodalKernel
    variable = u
    v = lm_upper
    coef = -1
  []
  [lower_bound]
    type = LowerBoundNodalKernel
    variable = lm_lower
    v = u
    exclude_boundaries = 'left right'
    lower_bound = 0
  []
  [forces_from_lower]
    type = CoupledForceNodalKernel
    variable = u
    v = lm_lower
    coef = 1
  []
[]


[BCs]
  [left]
    type = DirichletBC
    boundary = left
    value = 0
    variable = u
  []
  [right]
    type = DirichletBC
    boundary = right
    value = ${l}
    variable = u
  []
[]

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

[Executioner]
  type = Transient
  num_steps = ${num_steps}
  solve_type = NEWTON
  dtmin = 1
  petsc_options_iname = '-snes_max_linear_solve_fail -ksp_max_it -pc_type -sub_pc_factor_levels -snes_linesearch_type'
  petsc_options_value = '0                           30          asm      16                    basic'
[]

[Outputs]
  exodus = true
  [csv]
    type = CSV
    execute_on = 'nonlinear timestep_end'
  []
  [dof]
    type = DOFMap
    execute_on = 'initial'
  []
[]

[Debug]
  show_var_residual_norms = true
[]

[Postprocessors]
  [active_upper_lm]
    type = GreaterThanLessThanPostprocessor
    variable = lm_upper
    execute_on = 'nonlinear timestep_end'
    value = 1e-8
    comparator = 'greater'
  []
  [upper_violations]
    type = GreaterThanLessThanPostprocessor
    variable = u
    execute_on = 'nonlinear timestep_end'
    value = ${fparse 10+1e-8}
    comparator = 'greater'
  []
  [active_lower_lm]
    type = GreaterThanLessThanPostprocessor
    variable = lm_lower
    execute_on = 'nonlinear timestep_end'
    value = 1e-8
    comparator = 'greater'
  []
  [lower_violations]
    type = GreaterThanLessThanPostprocessor
    variable = u
    execute_on = 'nonlinear timestep_end'
    value = -1e-8
    comparator = 'less'
  []
  [nls]
    type = NumNonlinearIterations
  []
  [cum_nls]
    type = CumulativeValuePostprocessor
    postprocessor = nls
  []
[]

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Example Syntax
Input Parameters
Input Files

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