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2D NACA0012 O-Mesh GAMG Solver Floating Point Exception

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Old   March 16, 2015, 10:25
Default 2D NACA0012 O-Mesh GAMG Solver Floating Point Exception
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Michael Deaves
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Hi all!

Using the airFoil2D tutorial as a starting point I am trying to investigate the flow over a NACA0012 using SpallartAlmars turbulence model, wall functions, simpleFoam, and an O-Mesh that was generated in Pointwise.

When I run simpleFoam I get this error,

#0 Foam::error:rintStack(Foam::Ostream&) at ??:?
#1 Foam::sigFpe::sigHandler(int) at ??:?
#2 in "/lib/x86_64-linux-gnu/libc.so.6"
#3 Foam::GAMGSolver::scale(Foam::Field<double>&, Foam::Field<double>&, Foam::lduMatrix const&, Foam::FieldField<Foam::Field, double> const&, Foam::UPtrList<Foam::lduInterfaceField const> const&, Foam::Field<double> const&, unsigned char) const at ??:?
#4 Foam::GAMGSolver::Vcycle(Foam::PtrList<Foam::lduMa trix::smoother> const&, Foam::Field<double>&, Foam::Field<double> const&, Foam::Field<double>&, Foam::Field<double>&, Foam::Field<double>&, Foam::Field<double>&, Foam::Field<double>&, Foam::PtrList<Foam::Field<double> >&, Foam::PtrList<Foam::Field<double> >&, unsigned char) const at ??:?
#5 Foam::GAMGSolver::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const at ??:?
#6 Foam::fvMatrix<double>::solveSegregated(Foam::dict ionary const&) at ??:?
#7 Foam::fvMatrix<double>::solve(Foam::dictionary const&) at ??:?
#8
at ??:?
#9
at ??:?
#10 __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6"
#11
at ??:?
Floating point exception (core dumped)

I can understand enough to know that the solver GAMG is involved with some bad math (divide by zero maybe?), but I can't figure out much more than that. Hopefully you can help me.

My boundary conditions follow post #48 from jferrari on this thread. They are very simple for an O-mesh, only farfield, airfoil, and empty in the z-direction.

One weird thing is that when I use a C-Type mesh that I built using snappyHexMesh simpleFoam runs with no errors. However running the Pointwise O-mesh with the same solver settings and boundary conditions crashes simpleFoam. I have attached some of my case files as well as the log of checkMesh.

Any help is greatly appreciated.

-Michael
Attached Files
File Type: c checkMeshLog.c (2.9 KB, 6 views)
File Type: c fvSchemes.c (1.4 KB, 5 views)
File Type: c fvSolution.c (1.9 KB, 4 views)
File Type: c nuTilda.c (1.1 KB, 1 views)
File Type: c log.c (3.4 KB, 4 views)
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Old   March 16, 2015, 10:41
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Alexey Matveichev
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Hi,

You have convergence problem even before GAMG is invoked:

Code:
Time = 1

smoothSolver:  Solving for Ux, Initial residual = 1, Final residual = 259.68, No Iterations 1000
smoothSolver:  Solving for Uy, Initial residual = 1, Final residual = 7.08758, No Iterations 1000
...
As you can see, final residual is greater than initial and number of iterations are equal to maxIter.

Also you have got this warning:

Code:
--> FOAM Warning : 
    From function Field<Type>::Field(const word& keyword, const dictionary&, const label)
    in file /home/openfoam/OpenFOAM/OpenFOAM-2.3.1/src/OpenFOAM/lnInclude/Field.C at line 318
    Reading "/home/mdeaves/Dropbox/ProjectBoomerang/OpenFOAM/run/airFoil2DSA_Omesh/0/U.boundaryField.farfield" from line 25 to line 26
    expected keyword 'uniform' or 'nonuniform', assuming deprecated Field format from Foam version 2.0.
Can you post your U boundary conditions?
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Old   March 16, 2015, 10:49
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Michael Deaves
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Thanks for pointing that out!

I forgot to add 'uniform' in front of the U boundary condition on the farfield. Adding that removed the warning.

Attached is my U file and the new log file. Why would the smoothSolver be blowing up so quickly?
Attached Files
File Type: c log.c (3.0 KB, 3 views)
File Type: c U.c (1.1 KB, 6 views)
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Old   March 16, 2015, 12:03
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Michael Deaves
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Here are my other BC files too.
Attached Files
File Type: c p.c (1.0 KB, 2 views)
File Type: c nut.c (1.1 KB, 1 views)
File Type: c nuTilda.c (1.1 KB, 0 views)
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Old   September 23, 2019, 02:51
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chengan.wang
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Dear Michael Deaves,
Have you solved this problem? I meet the same problem with the mesh by pointwise.
Sincerely
Chengan
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airfoil 2d, floating point exception, o-mesh, openfoam 2.3.1, pointwise

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