CFD simulation of a converging diverging nozzle using argon

[arsadCFD]

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Question

Hi
I am new beginner in MOOSE and looking for help. Can somebody help me in the input file setup for simulation argon flow in cd nozzle. I generated .msh file and struggling to make input file. Can somebody give me input file?

[GiudGiud]

Hello

You'll want to follow the documentation in the Navier Stokes module.
https://mooseframework.inl.gov/modules/navier_stokes/index.html
There are examples in the modules/navier_stokes/examples folder, and many of the tests in modules/navier_stokes/test/tests/finite_volume are helpful as well

Guillaume

[arsadCFD]

Hi Guillaume
Thank you so much. /home/arsad/projects/moose/modules/navier_stokes/test/tests/finite_volume/cns

I found one folder 'stagnation_inlet' and simulated cd nozzle. But, I'm still not sure what gas is being simulated as the input file doesn't provide any information about it.

2. I generated my own cd nozzle using gmsh with the file name 'nozzle.msh' with the boundaries labeled as INFLOW,OUTFLOW and WALL. This geometry shows lots of error even after correcting BCs section.

here is the input file

stagnation_pressure = 101325.0
stagnation_temperature = 300.0

[GlobalParams]
  fp = fp
[]

[Debug]
   show_material_props = true
[]

[Mesh]
  [file]
    type = FileMeshGenerator
    file = nozzle.msh
  []
[]

[FluidProperties]
  [fp]
    type = IdealGasFluidProperties
    gamma = 1.4
    molar_mass = 0.02897024320557491
  []
[]

[Variables]
  [rho]
    family = MONOMIAL
    order = CONSTANT
    fv = true
    initial_condition = 0.0034
  []

  [rho_u]
    family = MONOMIAL
    order = CONSTANT
    fv = true
    initial_condition = 1e-4
    outputs = none
  []

  [rho_v]
    family = MONOMIAL
    order = CONSTANT
    fv = true
    outputs = none
  []

  [rho_E]
    family = MONOMIAL
    order = CONSTANT
    fv = true
    initial_condition = 2.5
  []
[]

[FVKernels]
  # Mass conservation
  [mass_time]
    type = FVTimeKernel
    variable = rho
  []

  [mass_advection]
    type = CNSFVMassHLLC
    variable = rho
  []

  # Momentum x conservation
  [momentum_x_time]
    type = FVTimeKernel
    variable = rho_u
  []

  [momentum_x_advection]
    type = CNSFVMomentumHLLC
    variable = rho_u
    momentum_component = x
  []

  # Momentum y conservation
  [momentum_y_time]
    type = FVTimeKernel
    variable = rho_v
  []

  [momentum_y_advection]
    type = CNSFVMomentumHLLC
    variable = rho_v
    momentum_component = y
  []

  # Fluid energy conservation
  [fluid_energy_time]
    type = FVTimeKernel
    variable = rho_E
  []

  [fluid_energy_advection]
    type = CNSFVFluidEnergyHLLC
    variable = rho_E
  []
[]

[FVBCs]
  ## inflow stagnation boundaries
  [mass_stagnation_inflow]
    type = CNSFVHLLCMassStagnationInletBC
    variable = rho
    stagnation_pressure = ${stagnation_pressure}
    stagnation_temperature = ${stagnation_temperature}
    boundary = INFLOW
  []

  [momentum_x_stagnation_inflow]
    type = CNSFVHLLCMomentumStagnationInletBC
    variable = rho_u
    momentum_component = x
    stagnation_pressure = ${stagnation_pressure}
    stagnation_temperature = ${stagnation_temperature}
    boundary = INFLOW
  []

  [momentum_y_stagnation_inflow]
    type = CNSFVHLLCMomentumStagnationInletBC
    variable = rho_v
    momentum_component = y
    stagnation_pressure = ${stagnation_pressure}
    stagnation_temperature = ${stagnation_temperature}
    boundary = INFLOW
  [../]

  [fluid_energy_stagnation_inflow]
    type = CNSFVHLLCFluidEnergyStagnationInletBC
    variable = rho_E
    stagnation_pressure = ${stagnation_pressure}
    stagnation_temperature = ${stagnation_temperature}
    boundary = INFLOW
  []

  ## outflow implicit conditions
  [mass_outflow]
    type = CNSFVHLLCMassImplicitBC
    variable = rho
    boundary = OUTFLOW
  []

  [momentum_x_outflow]
    type = CNSFVHLLCMomentumImplicitBC
    variable = rho_u
    momentum_component = x
    boundary = OUTFLOW
  []

  [momentum_y_outflow]
    type = CNSFVHLLCMomentumImplicitBC
    variable = rho_v
    momentum_component = y
    boundary = OUTFLOW
  []

  [fluid_energy_outflow]
    type = CNSFVHLLCFluidEnergyImplicitBC
    variable = rho_E
    boundary = OUTFLOW
  []

  # wall conditions
  [momentum_x_pressure_wall]
    type = CNSFVMomImplicitPressureBC
    variable = rho_u
    momentum_component = x
    boundary = WALL
  []

  [momentum_y_pressure_wall]
    type = CNSFVMomImplicitPressureBC
    variable = rho_v
    momentum_component = y
    boundary = WALL
  []
[]

[AuxVariables]
  [Ma]
    family = MONOMIAL
    order = CONSTANT
  []
  [p]
    family = MONOMIAL
    order = CONSTANT
  []
  [Ma_layered]
    family = MONOMIAL
    order = CONSTANT
  []
  [T_fluid]
    family = MONOMIAL
    order = CONSTANT
  []  
[]

[UserObjects]
  [layered_Ma_UO]
    type = LayeredAverage
    variable = Ma
    num_layers = 100
    direction = x
  []
[]

[AuxKernels]
  [Ma_aux]
    type = NSMachAux
    variable = Ma
    fluid_properties = fp
    use_material_properties = true
  []
  [p_aux]
    type = ADMaterialRealAux
    variable = p
    property = pressure
  []
  [Ma_layered_aux]
    type = SpatialUserObjectAux
    variable = Ma_layered
    user_object = layered_Ma_UO
  []
  [T_fluid]
    type = ADMaterialRealAux
    variable = T_fluid
    property = T_fluid
  []  
[]

[Materials]
  [var_mat]
    type = ConservedVarValuesMaterial
    rho = rho
    rhou = rho_u
    rhov = rho_v
    rho_et = rho_E
  []

  [fluid_props]
    type = GeneralFluidProps
    porosity = 1
    characteristic_length = 1
  []

  [sound_speed]
    type = SoundspeedMat
    fp = fp
  []
[]

[Postprocessors]
  [cfl_dt]
    type = ADCFLTimeStepSize
    c_names = 'sound_speed'
    vel_names = 'speed'
    CFL = 0.1
  []

  [outflow_Ma]
    type = SideAverageValue
    variable = Ma
    boundary = OUTFLOW
  []
    [outflow_pressure]
    type = SideAverageValue
    variable = p
    boundary = OUTFLOW
  []
[]

[Preconditioning]
  [smp]
    type = SMP
    full = true
    petsc_options_iname = '-pc_type'
    petsc_options_value = 'lu'
  []
[]

[Executioner]
  type = Transient
  end_time = 200.0

  [TimeIntegrator]
    type = ExplicitSSPRungeKutta
    order = 2
  []
  l_tol = 1e-8

  [TimeStepper]
    type = PostprocessorDT
    postprocessor = cfl_dt
  []
[]

[VectorPostprocessors]
  [Ma_layered]
    type = LineValueSampler
    variable = Ma_layered
    start_point = '0 0 0'
    end_point = '10 0 0'
    num_points = 100
    sort_by = x
  []
[]

[Outputs]
  exodus = true
[]

I wanna simulate argon flow using my nozzle. plz help

[GiudGiud]

So does the problem you are looking at involve significant depressurization / pressure & density changes?

The compressible formulation of the NS equations is a lot slower than our incompressible branch, so I just want to double check

[arsadCFD]

Hi Guillaume

Thank you so much for the response.

It's a simple converging-diverging nozzle of area ratio 6.89 and overall length 7.3 inches, throat radii 0.8 inches, exit radii 2.1 inches and inlet radii 2.5 inches.Assuming isentropic flow, the exit mach no. should be 3.5 for air and 4.2 for argon and it would definitely involve significant pressure/density changes. I chose this nozzle just for validation and next step is to simulate straight cylinder and similar other geometries where the flow would be driven predominatly by pressure differences involving slight density changes/weakly compressible or incompressible flows

a) /home/arsad/projects/moose/modules/navier_stokes/test/tests/finite_volume/cns/stagnation_inlet. Using the input file shown above, I wanna simulate my own cd nozzle 'nozzle.msh' for AIR and Argon. The nozzle boundaries are labeled as INFLOW, OUTFLOW and WALL. Do I have option of simulating only half geometry (axisymmetric nozzle). Also, I wanna impose pressure inlet 1mT and in another case flow rate inlet 10 sccm. How can I do it? The relevant tutorials didn't help.

b) Then simulate straight cylinder for above cases.

If could answer both the question, that would be much appreciated!

[GiudGiud]

Do I have option of simulating only half geometry (axisymmetric nozzle).

MOOSE does support symmetric boundary conditions. If the problem is already being solved in RZ coordinates (set this in the Mesh block), you just need to have 0 flux boundary conditions.

, I wanna impose pressure inlet

This is the fixed pressure BC (and liquid at rest in a tank connected to the domain)
https://mooseframework.inl.gov/source/fvbcs/CNSFVHLLCMassStagnationInletBC.html
https://mooseframework.inl.gov/source/fvbcs/CNSFVHLLCMomentumStagnationInletBC.html
same for energy

case flow rate inlet 10 sccm

This one for fixed mass flow rate
https://mooseframework.inl.gov/source/fvbcs/CNSFVHLLCMassBC.html
https://mooseframework.inl.gov/source/fvbcs/CNSFVHLLCMomentumBC.html
same for energy

vb) Then simulate straight cylinder for above cases.

Probably best to start with that before going to the nozzle.

generated my own cd nozzle using gmsh with the file name 'nozzle.msh' with the boundaries labeled as INFLOW,OUTFLOW and WALL. This geometry shows lots of error even after correcting BCs section.

You ll need to sort these out.
I think you can start by removing CNSFVMomImplicitPressureBC from the walls. I think implicit BCs are meant for outlets but I am not 100% sure

[arsadCFD]

Here is the cd nozzle I wanna simulate for validation

[GiudGiud]

thanks.
Just a note in case it ends up mattering,
You can probably generate a more regular mesh using Cubit and its sweeping algorithms, or using MOOSE with a GeneratedMeshGenerator and a ParsedNodeTransformation encoding the curve (might be tricky).