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simpleFoam bounding and time step continuity errors |
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November 21, 2011, 16:48 |
simpleFoam bounding and time step continuity errors
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#1 | |
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Hey all,
Quite new to OF so hope I can find some help here........! I'm trying to run a simpleFoam case on an aerofoil which I am meshing progressively finer and finer with gmsh. I am having trouble, however, seemingly when the mesh gets to a particular level of fineness..... I am using the spalmart-allmaras model. The timestep continuity errors shoot up massively as does the bounding of nuTilda (negative value). This is causing an exception error... I'm also getting a similar problem in another case using k-epsilon modelling, where the bounding of epsilon and k is similarly negative and very large (again occuring when the mesh becomes fine enough). Here is my fvSchemes file Quote:
Can anyone give me any hints/comments? |
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November 22, 2011, 03:50 |
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#2 |
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Alberto Passalacqua
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I would apply a limiter to the gradients: cellLimited Gauss linear 1; On unstructured grids, use least-squares.
Also, you might want to check your under-relaxation factors for the variables that become unbounded. Best,
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Alberto Passalacqua GeekoCFD - A free distribution based on openSUSE 64 bit with CFD tools, including OpenFOAM. Available as in both physical and virtual formats (current status: http://albertopassalacqua.com/?p=1541) OpenQBMM - An open-source implementation of quadrature-based moment methods. To obtain more accurate answers, please specify the version of OpenFOAM you are using. |
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November 22, 2011, 07:59 |
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#3 | |||
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Hi alberto,
I have tried changing my gradSchemes to Quote:
I've also tried reducing the relaxation factor for nuTilda (I think this is the correct thing to do but would welcome comments on why). I have Quote:
I am still getting the same error though..... here is an excerpt Quote:
And then it crashes with the exception error...... Hope you can help Regards, plm |
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November 22, 2011, 16:06 |
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#4 |
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Alberto Passalacqua
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Does the code run without problems if you turn off the turbulence model? It seems none of the equations is converging. I would start checking the setup of the boundary conditions, the mesh quality (checkMesh), ...
Best,
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Alberto Passalacqua GeekoCFD - A free distribution based on openSUSE 64 bit with CFD tools, including OpenFOAM. Available as in both physical and virtual formats (current status: http://albertopassalacqua.com/?p=1541) OpenQBMM - An open-source implementation of quadrature-based moment methods. To obtain more accurate answers, please specify the version of OpenFOAM you are using. |
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November 22, 2011, 16:50 |
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#5 | |
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Hi alberto, thanks once again for the help!
I've tried running without the turbulence model and it appears I am having problems with my mesh... checkMesh turns up this error Quote:
I will continue to investigate but would welcome any comments |
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November 22, 2011, 17:12 |
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#6 |
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alberto,
I seem to be getting a problem with undefined faces in OF when using gmshToFoam which I think is causing problems later on.... Would it be possible for you to take a look at my .geo file and see what you think - I'm not sure if you're familiar with gmsh but I can't spot any problems... Regards, plm |
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November 22, 2011, 22:20 |
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#7 |
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Alberto Passalacqua
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I am not very familiar with gmsh, sorry.
__________________
Alberto Passalacqua GeekoCFD - A free distribution based on openSUSE 64 bit with CFD tools, including OpenFOAM. Available as in both physical and virtual formats (current status: http://albertopassalacqua.com/?p=1541) OpenQBMM - An open-source implementation of quadrature-based moment methods. To obtain more accurate answers, please specify the version of OpenFOAM you are using. |
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November 30, 2016, 12:58 |
time step continuity errors
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#8 |
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Saurav Kumar
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same type of problem i am facing
Time = 63 smoothSolver: Solving for Ux, Initial residual = 0.407445, Final residual = 6.2409e-06, No Iterations 48 smoothSolver: Solving for Uy, Initial residual = 0.713688, Final residual = 8.41503e-06, No Iterations 40 GAMG: Solving for p, Initial residual = 1, Final residual = 0.281817, No Iterations 1000 time step continuity errors : sum local = 5.16688e+27, global = -3.34408e+27, cumulative = -3.34408e+27 smoothSolver: Solving for epsilon, Initial residual = 0.113747, Final residual = 5.51399e-06, No Iterations 2 bounding epsilon, min: -1.00648e+42 max: 2.17508e+52 average: 8.0165e+49 smoothSolver: Solving for k, Initial residual = 4.4491e-10, Final residual = 4.4491e-10, No Iterations 0 ExecutionTime = 30.43 s ClockTime = 31 s Time = 64 smoothSolver: Solving for Ux, Initial residual = 0.00072263, Final residual = 0.000301801, No Iterations 1000 smoothSolver: Solving for Uy, Initial residual = 0.00426629, Final residual = 0.000911303, No Iterations 1000 #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 Foam::fvMatrix<double>::solve() at ??:? #9 ? at ??:? #10 __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6" #11 ? at ??:? Floating point exception (core dumped) how did you solve it? thanks |
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March 27, 2018, 03:34 |
Floating point exception (core dumped)
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#9 |
New Member
Ali Mohammadi
Join Date: Oct 2017
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I solved this problem. i read in a forum that this error happens because of a division to zero. and this happend in my simulation because i put an inflation over a surface and the first layer was too small. i changed it and it worked.
You can also get rid of this error by changing the value of k and epsilon if you are using this model for as the turbulence model. |
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Tags |
aerofoil, bounding, gmsh, simplefoam, time step continuity |
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