I encountered this error this morning.

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--> FOAM FATAL IO ERROR:
inconsistent patch and patchField types for
    patch type symmetry and patchField type fixedValue

file: $case/k/boundaryField/walls from line 37 to line 38.

    From function static Foam::tmp<Foam::fvPatchField<Type> > Foam::fvPatchField<Type>::New(const Foam::fvPatch&, const Foam::DimensionedField<Type, Foam::volMesh>&, const Foam::dictionary&) [with Type = double]
    in file $OF_INSTALL/openmpi4/openfoam/9/OpenFOAM-9/src/finiteVolume/lnInclude/fvPatchFieldNew.C at line 154.

FOAM exiting

The error suggests that there is something wrong with boundary condition settings.

I’ve used many different types of boundary conditions in simulations, but the differences between them, especially the impact on aerodynamic forces are missing over the years. I’ve asked ChatGPT to list all the boundary types in OpenFOAM:

  • slip: Imposes slip conditions on velocity and zero gradient conditions on other scalar fields.
  • wall: Imposes no-slip conditions on velocity and zero gradient conditions on other scalar fields.
  • patch: Allows for slip conditions on velocity and specified gradient conditions on other scalar fields.
  • empty: Imposes zero gradient conditions on all fields.
  • symmetry: Imposes symmetry conditions on velocity and other scalar fields.
  • cyclic: Imposes cyclic conditions on fields between two or more patch boundaries.
  • fixedValue: Imposes fixed values on specified fields.
  • freestream: Imposes freestream conditions on velocity and other scalar fields.
  • inletOutlet: Imposes specified conditions on velocity and other scalar fields at an inlet-outlet boundary.
  • outletInlet: Imposes specified conditions on velocity and other scalar fields at an outlet-inlet boundary.
  • outlet: Imposes specified conditions on velocity and other scalar fields at an outlet boundary.
  • inlet: Imposes specified conditions on velocity and other scalar fields at an inlet boundary.
  • zeroGradient: Imposes zero gradient conditions on all fields.
  • fixedGradient: Imposes specified gradient conditions on all fields.
  • freeslip: Imposes freeslip conditions on velocity and zero gradient conditions on other scalar fields.
  • pressureInlet: Imposes specified pressure conditions on velocity and zero gradient conditions on other scalar fields.
  • pressureOutlet: Imposes specified pressure conditions and zero gradient conditions on velocity and other scalar fields.
  • fixedFluxPressure: Imposes specified flux and pressure conditions on velocity and other scalar fields.
  • turbulenceSpecification: Imposes specified turbulence conditions on velocity and other scalar fields.

The followings are not directly related to bluff body aerodynamics:

  • massFlowInlet: Imposes specified mass flow rate and zero gradient conditions on velocity and other scalar fields.
  • massFlowOutlet: Imposes specified mass flow rate and zero gradient conditions on velocity and other scalar fields.
  • fan: Imposes specified conditions on velocity and other scalar fields at a fan boundary.
  • mixer: Imposes specified conditions on velocity and other scalar fields at a mixer boundary.
  • heatFlux: Imposes specified heat flux conditions on temperature and zero gradient conditions on other scalar fields.
  • porous: Imposes porous conditions on velocity and other scalar fields.
  • porousPressure: Imposes specified pressure conditions and zero gradient conditions on velocity and other scalar fields.
  • porousVelocity: Imposes specified velocity conditions and zero gradient conditions on other scalar fields.
  • coupled: Imposes conditions for coupling with other solvers or simulations.
  • processor: Imposes conditions for parallel processing on fields.

The questions are:

  1. What are difference using inletOutlet and fixedValue at the inlet?

  2. What are difference using inletOutlet and outletInlet at the inlet?

  3. What are difference using empty and slip conditions for the boundary conditions on the wall?

  4. In what conditions, each type of boundary condition is the best suited for the specified physical condition?

    etc…

I intent to consult ChatGPT and talk about it in the future post. Also, CFD simulations will be used to see the differences.