INSAD Inlet Pressure Fluctuations

[TLWise]

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Question

My model developed using INSAD has sawtoothed shaped pressure fluctuations at the inlet even though I have prescribed a constant velocity profile at the inlet. This appears to have the same sawtooth profile as that of the drag coefficient on an object in the flow path. Is there a better NS formulation to use to eliminate such numerical instability?

[GiudGiud]

Hello

The plots are not legible.
INSAD can do inlet velocity problems. There is probably a mistake in the setup.

[GiudGiud]

@TLWise these plots need x and y labels

could you please send the console log?

[TLWise]

DFG_Benchmark_GeneratedMesh_console.txt

[GiudGiud]

the file did not upload, it s just a link to the post rn

[TLWise]

It should be available now. I did not wait long enough for the upload to complete the last time.

[GiudGiud]

ok not a convergence issue seemingly.
Did you attach the input somewhere? My next lead would be an error in the setup. Possibly with the integration by parts option in INSAD

[TLWise]

[Kernels]
  [mass]
    type = INSADMass
    variable = pressure
  []
  [mass_pspg]
    type = INSADMassPSPG
    variable = pressure
  []
  [momentum_time]
    type = INSADMomentumTimeDerivative
    variable = velocity
  []
  [momentum_convection]
    type = INSADMomentumAdvection
    variable = velocity
  []
  [momentum_viscous]
    type = INSADMomentumViscous
    variable = velocity
  []
  [momentum_pressure]
    type = INSADMomentumPressure
    variable = velocity
    pressure = 'pressure'
    integrate_p_by_parts = true
  []
  [momentum_supg]
    type = INSADMomentumSUPG
    variable = velocity
    velocity = 'velocity'
  []
[]

[lindsayad]

We would need to see the boundary conditions too. Can you send the full input so we can run it?

[TLWise]

DFG_Benchmark_GeneratedMeshshort.i.txt

[GiudGiud]

This is flow over circle but with an asymmetric mesh.
The solution is oscillating, with the flow going from from left to right
And so the pressure at the inlet is also oscillating (roughly by 4e-3)

If you refine the mesh once (-r 1) the oscillations go down to 1e-3.
You could try refining further

We have this case documented here, using the linearFV discretization
https://mooseframework.inl.gov/open_pronghorn/validation/free_flow/isothermal/vortex_shedding/cylinder/vortex-cylinder.html