Free surface fluid boundary condition

Applies a mixed Dirichlet-Neumann BC on the fluid surface.

Description

The free surface fluid BC applies a mixed Dirichlet-Neumann condition to simulate gravity waves. This condition is as follows:

$(1)var element = document.getElementById("moose-equation-71470a37-31d4-4f3b-a1c6-b1d052d924be");katex.render(" \\frac{\\partial p}{\\partial z} = -\\alpha~\\frac{\\partial^2p}{\\partial t^2}", element, {displayMode:true,throwOnError:false,macros:{"\\eqc":"\\,,","\\eqp":"\\,.","\\pd":"\\frac{\\partial #1}{\\partial #2}","\\pr":"\\left(#1\\right)","\\ddt":"\\frac{d #1}{d t}"}});$

where, $var element = document.getElementById("moose-equation-e5b4e60d-cb6b-4809-b8ee-e563844f0a9c");katex.render("p", element, {displayMode:false,throwOnError:false,macros:{"\\eqc":"\\,,","\\eqp":"\\,.","\\pd":"\\frac{\\partial #1}{\\partial #2}","\\pr":"\\left(#1\\right)","\\ddt":"\\frac{d #1}{d t}"}});$ is the fluid pressure and $var element = document.getElementById("moose-equation-0b5280b9-239f-416c-9609-2746eb908456");katex.render("g", element, {displayMode:false,throwOnError:false,macros:{"\\eqc":"\\,,","\\eqp":"\\,.","\\pd":"\\frac{\\partial #1}{\\partial #2}","\\pr":"\\left(#1\\right)","\\ddt":"\\frac{d #1}{d t}"}});$ is the acceleration due to gravity. This BC is part of the fluid-structure interaction codes. Please refer to fluid-structure interaction using acoustics for the theoretical details.

Input Parameters

boundaryThe list of boundary IDs from the mesh where this boundary condition applies
C++ Type:std::vector<BoundaryName>
Controllable:No
Description:The list of boundary IDs from the mesh where this boundary condition applies
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

alpha0.1Inverse of the acceleration due to gravity.
Default:0.1
C++ Type:double
Controllable:No
Description:Inverse of the acceleration due to gravity.
displacementsThe displacements
C++ Type:std::vector<VariableName>
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
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.

Optional 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 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<AuxVariableName>
Controllable:No
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.)
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 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<AuxVariableName>
Controllable:No
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.)
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

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

Input Files

(modules/fsi/test/tests/fsi_acoustics/wave_height_bc/wave_height_bc.i)

(modules/fsi/test/tests/fsi_acoustics/wave_height_bc/wave_height_bc.i)

# Test for `FluidFreeSurfaceBC` BC with only the fluid domain. The domain is 3D with
# lengths 1 X 1 X 0.01 meters. It is subjected to a 2D Gaussian initial condition
# with the peak at the midpoint (0.5, 0.5, 0.01). Wave heights are recorded at the
# midpoint at different times. The recorded wave heights should match with the values
# that are provided.

# Input parameters:
# Dimensions = 3
# Lengths = 1 X 1 X 0.01 meters
# Fluid speed of sound = 1500 m/s
# Initial condition = 0.00001*exp(-((x-0.5)/0.1)^2-((y-0.5)/0.1)^2)
# Fluid domain = true
# Fluid BCs = pressures are zero on all the four edges of the domain and `FluidFreeSurfaceBC` is applied on the front
# Structural domain = false

[Mesh]
  [gen]
    type = GeneratedMeshGenerator
    dim = 3
    nx = 15
    ny = 15
    nz = 1
    xmax = 1
    ymax = 1
    zmax = 0.01
  []
[]

[GlobalParams]
[]

[Variables]
  [./p]
  [../]
[]

[AuxVariables]
  [./Wave1]
  [../]
[]

[Kernels]
  [./diffusion]
    type = Diffusion
    variable = 'p'
  [../]
  [./inertia]
    type = AcousticInertia
    variable = p
  [../]
[]

[AuxKernels]
  [./waves]
    type = WaveHeightAuxKernel
    variable = 'Wave1'
    pressure = p
    density = 1e-6
    gravity = 9.81
    execute_on = timestep_end
  [../]
[]

[BCs]
  [./leftright_pressure]
    type = DirichletBC
    variable = p
    boundary = 'left right top bottom'
    value = 0
  [../]
  [./free]
    type = FluidFreeSurfaceBC
    variable = p
    boundary = 'front'
    alpha = '0.1'
  []
[]

[ICs]
  [./u_ic]
    type = FunctionIC
    variable = 'p'
    function = initial_cond
    boundary = 'front'
  [../]
[]

[Functions]
  [./initial_cond]
    type = ParsedFunction
    value = '0.00001*exp(-((x-0.5)/0.1)^2-((y-0.5)/0.1)^2)'
  [../]
[]

[Materials]
  [./co_sq]
    type = GenericConstantMaterial
    prop_names = inv_co_sq
    prop_values = 4.44e-7
  [../]
[]

[Executioner]
  type = Transient
  solve_type = 'NEWTON'
  petsc_options_iname = '-pc_type -pc_factor_mat_solver_package'
  petsc_options_value = 'lu       superlu_dist'
  start_time = 0.0
  end_time = 0.2
  dt = 0.005
  dtmin = 0.00001
  nl_abs_tol = 1e-12
  nl_rel_tol = 1e-12
  l_tol = 1e-12
  l_max_its = 25
  timestep_tolerance = 1e-8
  automatic_scaling = true
  [TimeIntegrator]
    type = NewmarkBeta
  []
[]

[Postprocessors]
  [./W1]
    type = PointValue
    point = '0.5 0.5 0.01'
    variable = Wave1
  [../]
[]

[Outputs]
  csv = true
  exodus = true
  perf_graph = true
  print_linear_residuals = true
[]

Description
Input Parameters
Input Files

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