LBMComputeForces

Compute object for LB forces

LBMComputeForces calculates forces for LBM simulations. Currently available forces are gravity and buoyancy.

Overview

Computes body force contributions (e.g., gravity or external driving force) required by the LBM forcing term. For gravity, set "enable_gravity" to true and supply gravitational acceleration via "gravity". Please not that gravity is applied in y direction by default, but it can be changed to x or z by setting "gravity_direction" to 0 or 2 respectively. When coupling heat and mass transfer to enable Boussinesq approximation of buoyancy, set "enable_buoyancy" to true and supply temperature buffer via "temperature", reference temperature via "T0" and reference density via "rho0". output force buffer via "buffer".

Example Input File Syntax

[TensorComputes<<<{"href": "../../syntax/TensorComputes/index.html"}>>>]
  [Solve<<<{"href": "../../syntax/TensorComputes/Solve/index.html"}>>>]
    [Compute_forces]
      type = LBMComputeForces<<<{"description": "Compute object for LB forces", "href": "LBMComputeForces.html"}>>>
      buffer<<<{"description": "The buffer this compute is writing to"}>>> = F
      rho0<<<{"description": "Reference density"}>>> = 'rho0'
      temperature<<<{"description": "Macroscopic temperature"}>>> = T
      T0<<<{"description": "Reference temperature"}>>> = 1.00
      enable_buoyancy<<<{"description": "Whether to consider buoyancy"}>>> = true
      gravity<<<{"description": "Gravitational accelaration"}>>> = g
      gravity_direction<<<{"description": "Gravitational accelaration direction"}>>> = 2
    []
  []
[]

Input Parameters

bufferThe buffer this compute is writing to
C++ Type:std::string
Controllable:No
Description:The buffer this compute is writing to

Required Parameters

T01.0Reference temperature
Default:1.0
C++ Type:std::string
Controllable:No
Description:Reference temperature
enable_buoyancyFalseWhether to consider buoyancy
Default:False
C++ Type:bool
Controllable:No
Description:Whether to consider buoyancy
enable_gravityFalseWhether to consider gravity
Default:False
C++ Type:bool
Controllable:No
Description:Whether to consider gravity
gravity0.001Gravitational accelaration
Default:0.001
C++ Type:std::string
Controllable:No
Description:Gravitational accelaration
gravity_direction1Gravitational accelaration direction
Default:1
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:Gravitational accelaration direction
rhorhoMacroscopic density
Default:rho
C++ Type:std::string
Controllable:No
Description:Macroscopic density
rho01.0Reference density
Default:1.0
C++ Type:std::string
Controllable:No
Description:Reference density
temperatureTMacroscopic temperature
Default:T
C++ Type:std::string
Controllable:No
Description:Macroscopic temperature

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.
enableTrueSet the enabled status of the MooseObject.
Default:True
C++ Type:bool
Controllable:No
Description:Set the enabled status of the MooseObject.

Advanced Parameters

Input Files

(examples/lbm/natural_convection_3D/convection.i)
(examples/lbm/Rayleigh-Benard/solve.i)
(examples/lbm/Pebbles/pebbles.i)

(examples/lbm/natural_convection_3D/convection.i)

[Domain]
  dim = 3
  nx = 270
  ny = 270
  nz = 405
  xmax = 270
  ymax = 270
  zmax = 405
  device_names='cpu'
  parallel_mode = REAL_SPACE
  periodic_directions = 'X Y Z'
  floating_precision=SINGLE
[]

[Stencil]
  [d3q19]
    type = LBMD3Q19
  []
[]

[TensorBuffers]
  # Simulation binary media
  [binary_media]
    type = LBMTensorBuffer
    file = binary_media.h5
    buffer_type = ms
    is_integer = true
  []

  # Density distribution functions
  [f]
    type = LBMTensorBuffer
    buffer_type = df
  []
  [feq]
    type = LBMTensorBuffer
    buffer_type = df
  []
  [fpc]
    type = LBMTensorBuffer
    buffer_type = df
  []
  # Temperature distribution functions
  [g]
    type = LBMTensorBuffer
    buffer_type = df
  []
  [geq]
    type = LBMTensorBuffer
    buffer_type = df
  []
  [gpc]
    type = LBMTensorBuffer
    buffer_type = df
  []
  # Fluid macroscopic variables: density and velocity
  [density]
    type = LBMTensorBuffer
    buffer_type = ms
  []
  [velocity]
    type = LBMTensorBuffer
    buffer_type = mv
  []
  [speed]
    type=LBMTensorBuffer
    buffer_type = ms
  []
  # Temperature macroscpic variables: temperature and 'velocity'
  [T]
    type = LBMTensorBuffer
    buffer_type = ms
  []
  # Forces
  [F]
    type = LBMTensorBuffer
    buffer_type = mv
  []
[]

[TensorComputes]
  [Initialize]
    [density]
      type = LBMConstantTensor
      buffer = density
      constants = 'rho0'
    []
    [velocity]
      type = LBMConstantTensor
      buffer = velocity
      constants = '0.0 0.0 0.0'
    []
    [temperature]
      type = LBMConstantTensor
      buffer = T
      constants = T_C
    []
    [equilibrium_fluid]
      type = LBMEquilibrium
      buffer = feq
      bulk = density
      velocity = velocity
    []
    [equilibrium_fluid_total]
      type = LBMEquilibrium
      buffer = f
      bulk = density
      velocity = velocity
    []
    [equilibrium_fluid_pc]
      type = LBMEquilibrium
      buffer = fpc
      bulk = density
      velocity = velocity
    []
    [equilibrium_temperature]
      type = LBMEquilibrium
      buffer = geq
      bulk = T
      velocity = velocity
    []
    [equilibrium_temperature_total]
      type = LBMEquilibrium
      buffer = g
      bulk = T
      velocity = velocity
    []
    [equilibrium_temperature_pc]
      type = LBMEquilibrium
      buffer = gpc
      bulk = T
      velocity = velocity
    []
  []

  #### Compute ####
  [Solve]

    # For temperature
    [Temperature]
      type = LBMComputeDensity
      buffer = T
      f = g
    []

    # For fluid
    [Fluid_density]
      type = LBMComputeDensity
      buffer = density
      f = f
    []

    [Fluid_velocity]
      type = LBMComputeVelocity
      buffer = velocity
      f = f
      rho = density
      forces = F
      enable_forces = true
    []

    # For temperature
    [Equilibrium_temperature]
      type = LBMEquilibrium
      buffer = geq
      bulk = T
      velocity = velocity
    []

    [Collision_temperature]
      type = LBMBGKCollision
      buffer = gpc
      f = g
      feq = geq
      tau0 = tau_T
    []

    # For fluid
    [Compute_forces]
      type = LBMComputeForces
      buffer = F
      rho0 = 'rho0'
      temperature = T
      T0 = 1.00
      enable_buoyancy = true
      gravity = g
      gravity_direction = 2
    []

    [Equilibrium_fluid]
      type = LBMEquilibrium
      buffer = feq
      bulk = density
      velocity = velocity
    []

    [Collision_fluid]
      type = LBMBGKCollision
      buffer = fpc
      f = f
      feq = feq
      tau0 = tau_f
    []

    [Apply_forces]
      type = LBMApplyForces
      buffer = fpc
      velocity = velocity
      rho = density
      forces = F
      tau0 = tau_f
    []

    [Residual]
      type = LBMComputeResidual
      speed = T
      # TODO this buffer is redundant, but avoids 'missing parameter' error
      buffer = T
    []
  []

  #### Boundary ####
  [Boundary]
    ##### for fluid
    [wall]
      type = LBMBounceBack
      buffer = f
      f_old = fpc
      boundary = wall
    []
    ##### for temperature
    [heat_source]
      type = LBMNeumannBC
      buffer = g
      f_old = gpc
      feq=geq
      velocity = velocity
      rho = T
      gradient = 0.001
      region_id = 3
      boundary = regional
    []
    [walls]
      type = LBMDirichletBC
      buffer = g
      f_old = gpc
      feq=geq
      velocity = velocity
      rho = T
      value = 1.0
      region_id = 2
      boundary = regional
    []
  []
[]

[TensorSolver]
  type = LBMStream
  buffer = 'f g'
  f_old = 'fpc gpc'
  root_compute = Residual
[]

[Problem]
  type = LatticeBoltzmannProblem
  binary_media = binary_media
  scalar_constant_names = 'rho0 T_C T_H tau_f tau_T g'
  scalar_constant_values = '1.0 1.0 1.05 0.55 0.55 0.01'
  substeps = 100
  print_debug_output = true
[]

[Executioner]
  type = Transient
  num_steps = 1000
[]

[TensorOutputs]
  [xdmf2]
    type = XDMFTensorOutput
    buffer = 'T density velocity'
    output_mode = 'Cell Cell Cell'
    enable_hdf5 = true
  []
[]

(examples/lbm/natural_convection_3D/convection.i)

[Domain]
  dim = 3
  nx = 270
  ny = 270
  nz = 405
  xmax = 270
  ymax = 270
  zmax = 405
  device_names='cpu'
  parallel_mode = REAL_SPACE
  periodic_directions = 'X Y Z'
  floating_precision=SINGLE
[]

[Stencil]
  [d3q19]
    type = LBMD3Q19
  []
[]

[TensorBuffers]
  # Simulation binary media
  [binary_media]
    type = LBMTensorBuffer
    file = binary_media.h5
    buffer_type = ms
    is_integer = true
  []

  # Density distribution functions
  [f]
    type = LBMTensorBuffer
    buffer_type = df
  []
  [feq]
    type = LBMTensorBuffer
    buffer_type = df
  []
  [fpc]
    type = LBMTensorBuffer
    buffer_type = df
  []
  # Temperature distribution functions
  [g]
    type = LBMTensorBuffer
    buffer_type = df
  []
  [geq]
    type = LBMTensorBuffer
    buffer_type = df
  []
  [gpc]
    type = LBMTensorBuffer
    buffer_type = df
  []
  # Fluid macroscopic variables: density and velocity
  [density]
    type = LBMTensorBuffer
    buffer_type = ms
  []
  [velocity]
    type = LBMTensorBuffer
    buffer_type = mv
  []
  [speed]
    type=LBMTensorBuffer
    buffer_type = ms
  []
  # Temperature macroscpic variables: temperature and 'velocity'
  [T]
    type = LBMTensorBuffer
    buffer_type = ms
  []
  # Forces
  [F]
    type = LBMTensorBuffer
    buffer_type = mv
  []
[]

[TensorComputes]
  [Initialize]
    [density]
      type = LBMConstantTensor
      buffer = density
      constants = 'rho0'
    []
    [velocity]
      type = LBMConstantTensor
      buffer = velocity
      constants = '0.0 0.0 0.0'
    []
    [temperature]
      type = LBMConstantTensor
      buffer = T
      constants = T_C
    []
    [equilibrium_fluid]
      type = LBMEquilibrium
      buffer = feq
      bulk = density
      velocity = velocity
    []
    [equilibrium_fluid_total]
      type = LBMEquilibrium
      buffer = f
      bulk = density
      velocity = velocity
    []
    [equilibrium_fluid_pc]
      type = LBMEquilibrium
      buffer = fpc
      bulk = density
      velocity = velocity
    []
    [equilibrium_temperature]
      type = LBMEquilibrium
      buffer = geq
      bulk = T
      velocity = velocity
    []
    [equilibrium_temperature_total]
      type = LBMEquilibrium
      buffer = g
      bulk = T
      velocity = velocity
    []
    [equilibrium_temperature_pc]
      type = LBMEquilibrium
      buffer = gpc
      bulk = T
      velocity = velocity
    []
  []

  #### Compute ####
  [Solve]

    # For temperature
    [Temperature]
      type = LBMComputeDensity
      buffer = T
      f = g
    []

    # For fluid
    [Fluid_density]
      type = LBMComputeDensity
      buffer = density
      f = f
    []

    [Fluid_velocity]
      type = LBMComputeVelocity
      buffer = velocity
      f = f
      rho = density
      forces = F
      enable_forces = true
    []

    # For temperature
    [Equilibrium_temperature]
      type = LBMEquilibrium
      buffer = geq
      bulk = T
      velocity = velocity
    []

    [Collision_temperature]
      type = LBMBGKCollision
      buffer = gpc
      f = g
      feq = geq
      tau0 = tau_T
    []

    # For fluid
    [Compute_forces]
      type = LBMComputeForces
      buffer = F
      rho0 = 'rho0'
      temperature = T
      T0 = 1.00
      enable_buoyancy = true
      gravity = g
      gravity_direction = 2
    []

    [Equilibrium_fluid]
      type = LBMEquilibrium
      buffer = feq
      bulk = density
      velocity = velocity
    []

    [Collision_fluid]
      type = LBMBGKCollision
      buffer = fpc
      f = f
      feq = feq
      tau0 = tau_f
    []

    [Apply_forces]
      type = LBMApplyForces
      buffer = fpc
      velocity = velocity
      rho = density
      forces = F
      tau0 = tau_f
    []

    [Residual]
      type = LBMComputeResidual
      speed = T
      # TODO this buffer is redundant, but avoids 'missing parameter' error
      buffer = T
    []
  []

  #### Boundary ####
  [Boundary]
    ##### for fluid
    [wall]
      type = LBMBounceBack
      buffer = f
      f_old = fpc
      boundary = wall
    []
    ##### for temperature
    [heat_source]
      type = LBMNeumannBC
      buffer = g
      f_old = gpc
      feq=geq
      velocity = velocity
      rho = T
      gradient = 0.001
      region_id = 3
      boundary = regional
    []
    [walls]
      type = LBMDirichletBC
      buffer = g
      f_old = gpc
      feq=geq
      velocity = velocity
      rho = T
      value = 1.0
      region_id = 2
      boundary = regional
    []
  []
[]

[TensorSolver]
  type = LBMStream
  buffer = 'f g'
  f_old = 'fpc gpc'
  root_compute = Residual
[]

[Problem]
  type = LatticeBoltzmannProblem
  binary_media = binary_media
  scalar_constant_names = 'rho0 T_C T_H tau_f tau_T g'
  scalar_constant_values = '1.0 1.0 1.05 0.55 0.55 0.01'
  substeps = 100
  print_debug_output = true
[]

[Executioner]
  type = Transient
  num_steps = 1000
[]

[TensorOutputs]
  [xdmf2]
    type = XDMFTensorOutput
    buffer = 'T density velocity'
    output_mode = 'Cell Cell Cell'
    enable_hdf5 = true
  []
[]

(examples/lbm/Rayleigh-Benard/solve.i)

#### Compute ####
[Solve]

  # For temperature
  [Temperature]
    type = LBMComputeDensity
    buffer = T
    f = g
  []

  # For fluid
  [Fluid_density]
    type = LBMComputeDensity
    buffer = density
    f = f
  []

  [Fluid_velocity]
    type = LBMComputeVelocity
    buffer = velocity
    f = f
    rho = density
    forces = F
    enable_forces = true
  []

  # For temperature
  [Equilibrium_temperature]
    type = LBMEquilibrium
    buffer = geq
    bulk = T
    velocity = velocity
  []

  [Collision_temperature]
    type = LBMBGKCollision
    buffer = gpc
    f = g
    feq = geq
    tau0 = tau_T
  []

  # For fluid
  [Compute_forces]
    type = LBMComputeForces
    buffer = F
    rho0 = 'rho0'
    temperature = T
    T0 = T_0
    enable_buoyancy = true
    gravity = g
  []

  [Equilibrium_fluid]
    type = LBMEquilibrium
    buffer = feq
    bulk = density
    velocity = velocity
  []

  [Collision_fluid]
    type = LBMBGKCollision
    buffer = fpc
    f = f
    feq = feq
    tau0 = tau_f
  []

  [Apply_forces]
    type = LBMApplyForces
    buffer = fpc
    velocity = velocity
    rho = density
    forces = F
    tau0 = tau_f
  []

  [Residual]
    type = LBMComputeResidual
    speed = T
    # TODO this buffer is redundant, but avoids 'missing parameter' error
    buffer = T
  []
[]

(examples/lbm/Pebbles/pebbles.i)

[Domain]
  dim = 3
  nx = 240
  ny = 50
  nz = 50
  xmax = 240
  ymax = 50
  zmax = 50
  device_names='cpu'
  # floating_precision = 'single'
  parallel_mode = REAL_SPACE
  periodic_directions = 'X Y'
[]

[Stencil]
  [d3q19]
    type = LBMD3Q19
  []
[]

[TensorBuffers]
  # Density distribution functions
  [f]
    type = LBMTensorBuffer
    buffer_type = df
  []
  [feq]
    type = LBMTensorBuffer
    buffer_type = df
  []
  [fpc]
    type = LBMTensorBuffer
    buffer_type = df
  []
  # Temperature distribution functions
  [g]
    type = LBMTensorBuffer
    buffer_type = df
  []
  [geq]
    type = LBMTensorBuffer
    buffer_type = df
  []
  [gpc]
    type = LBMTensorBuffer
    buffer_type = df
  []
  # Fluid macroscopic variables: density and velocity
  [density]
    type = LBMTensorBuffer
    buffer_type = ms
  []
  [velocity]
    type = LBMTensorBuffer
    buffer_type = mv
  []
  [speed]
    type=LBMTensorBuffer
    buffer_type = ms
  []
  # Temperature macroscpic variables: temperature and 'velocity'
  [T]
    type = LBMTensorBuffer
    buffer_type = ms
  []
  # Forces
  [F]
    type = LBMTensorBuffer
    buffer_type = mv
  []
  # Simulation domain
  [binary_media]
    type = LBMTensorBuffer
    buffer_type = ms
    file = 'binary_media.h5'
    is_integer = true
  []
[]

[TensorComputes]

  #### Initialzie ####
  [Initialize]
    [density]
      type = LBMConstantTensor
      buffer = density
      constants = 'rho0'
    []

    [velocity]
      type = LBMConstantTensor
      buffer = velocity
      constants = '0.0 0.0'
    []

    [temperature]
      type = LBMConstantTensor
      buffer = T
      constants = T_C
    []

    [equilibrium_fluid]
      type = LBMEquilibrium
      buffer = feq
      bulk = density
      velocity = velocity
    []

    [equilibrium_fluid_total]
      type = LBMEquilibrium
      buffer = f
      bulk = density
      velocity = velocity
    []

    [equilibrium_fluid_pc]
      type = LBMEquilibrium
      buffer = fpc
      bulk = density
      velocity = velocity
    []

    [equilibrium_temperature]
      type = LBMEquilibrium
      buffer = geq
      bulk = T
      velocity = velocity
    []

    [equilibrium_temperature_total]
      type = LBMEquilibrium
      buffer = g
      bulk = T
      velocity = velocity
    []

    [equilibrium_temperature_pc]
      type = LBMEquilibrium
      buffer = gpc
      bulk = T
      velocity = velocity
    []

    # [t_wall_hot_init]
    #   type = LBMDirichletWallBC
    #   buffer = g
    #   f_old = gpc
    #   value = T_H
    #   velocity = velocity
    #   boundary = wall
    # []
  []

  #### Compute ####
  [Solve]

    # For temperature
    [Temperature]
      type = LBMComputeDensity
      buffer = T
      f = g
    []

    # For fluid
    [Fluid_density]
      type = LBMComputeDensity
      buffer = density
      f = f
    []

    [Fluid_velocity]
      type = LBMComputeVelocity
      buffer = velocity
      f = f
      rho = density
      forces = F
      enable_forces = true
    []

    # For temperature
    [Equilibrium_temperature]
      type = LBMEquilibrium
      buffer = geq
      bulk = T
      velocity = velocity
    []

    [Collision_temperature]
      type = LBMMRTCollision
      buffer = gpc
      f = g
      feq = geq
      tau0 = tau_T
    []

    # For fluid
    [Compute_forces]
      type = LBMComputeForces
      buffer = F
      rho0 = 'rho0'
      temperature = T
      T0 = T_H
      enable_buoyancy = true
      gravity = g
      gravity_direction=0
    []

    [Equilibrium_fluid]
      type = LBMEquilibrium
      buffer = feq
      bulk = density
      velocity = velocity
    []

    [Collision_fluid]
      type = LBMMRTCollision
      buffer = fpc
      f = f
      feq = feq
      tau0 = tau_f
    []

    [Apply_forces]
      type = LBMApplyForces
      buffer = fpc
      velocity = velocity
      rho = density
      forces = F
      tau0 = tau_f
    []

    [speed]
      type=LBMComputeVelocityMagnitude
      buffer=speed
      velocity=velocity
    []

    [residual]
      type = LBMComputeResidual
      buffer = speed
      speed = speed
    []
  []

  #### Boundary ####
  [Boundary]
    ##### for fluid
    [inlet]
      type = LBMFixedFirstOrderBC
      buffer = f
      f = f
      value = u0
      boundary = left
    []
    [outlet]
      type = LBMMicroscopicZeroGradientBC
      buffer = f
      boundary = right
    []
    [top]
      type = LBMBounceBack
      buffer = f
      f_old = fpc
      boundary = top
      # exclude_corners_x = true
    []
    [bottom]
      type = LBMBounceBack
      buffer = f
      f_old = fpc
      boundary = bottom
      # exclude_corners_x = true
    []
    [front]
      type = LBMBounceBack
      buffer = f
      f_old = fpc
      boundary = front
      # exclude_corners_x = true
    []
    [back]
      type = LBMBounceBack
      buffer = f
      f_old = fpc
      boundary = back
      # exclude_corners_x = true
    []
    [wall]
      type = LBMBounceBack
      buffer = f
      f_old = fpc
      boundary = wall
    []

    ##### for temperature
    [t_inlet]
      type = LBMFixedZerothOrderBC
      buffer = g
      f = g
      value = T_C
      boundary = left
    []
    [t_outlet]
      type = LBMMicroscopicZeroGradientBC
      buffer = g
      boundary = right
    []
    [t_top]
      type = LBMBounceBack
      buffer = g
      f_old = gpc
      boundary = top
    []
    [t_bottom]
      type = LBMBounceBack
      buffer = g
      f_old = gpc
      boundary = bottom
    []
    [t_front]
      type = LBMBounceBack
      buffer = g
      f_old = gpc
      boundary = front
    []
    [t_back]
      type = LBMBounceBack
      buffer = g
      f_old = gpc
      boundary = back
    []
    [t_wall_hot]
      type = LBMDirichletBC
      buffer = g
      f_old = gpc
      feq = geq
      velocity = velocity
      rho = T
      value = 1.2
      boundary = wall
    []
  []
[]

[TensorSolver]
  type = LBMStream
  buffer = 'f g'
  f_old = 'fpc gpc'
  root_compute = residual
[]

[Problem]
  type = LatticeBoltzmannProblem
  substeps = 20
  scalar_constant_names = 'rho0 T_C T_H tau_f tau_T g u0'
  scalar_constant_values = '1.0 1.0 1.2 0.9 0.9 0.001 0.001'

  is_binary_media = true
  binary_media = binary_media
[]

[Postprocessors]
  [reynolds]
    type = ComputeReynoldsNumber
    buffer = speed
    tau = tau_f
    diameter = 15
  []
[]

[Executioner]
  type = Transient
  num_steps = 2000
[]

# [TensorOutputs]
#   [xdmf2]
#     type = XDMFTensorOutput
#     buffer = 'binary_media'
#     output_mode = 'Cell'
#     enable_hdf5 = true
#   []
# []

[TensorOutputs]
  [xdmf2]
    type = XDMFTensorOutput
    buffer = 'T velocity density binary_media'
    output_mode = 'Cell Cell Cell Cell'
    enable_hdf5 = true
  []
[]

Overview
Example Input File Syntax
Input Parameters
Input Files