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-   -   GAMG issue (http://www.cfd-online.com/Forums/openfoam/110001-gamg-issue.html)

phsieh2005 December 2, 2012 16:35

GAMG issue
 
Dear OpenFOAMers,

I am solving a chtMultiRegionSimpleFoam case. On the air domain, for p_rgh, when I used GAMG solver, I got floating point exception right away, however, when I switched to PCG with DIC preconditioner, the case run fine - just converging slower. I am wondering what settings I can change to resolve the GAMG issue.

Thanks!

Pei-Ying
------------------------
GAMG setting used:
p_rgh
{
solver GAMG;
tolerance 1e-7;
relTol 0.01;

smoother GaussSeidel;

cacheAgglomeration true;
nCellsInCoarsestLevel 10;
agglomerator faceAreaPair;
mergeLevels 1;

maxIter 100;
}
--------------------
PCG that worked

solver PCG;
preconditioner DIC;
tolerance 1e-7;
relTol 0.01;
-----------------
error messages:
#0 Foam::errorprintStack(Foam::Ostream&) in "/home/hsieh/OpenFOAM/OpenFOAM-2.1.x/platforms/linux64Gcc46DPOpt/lib/libOpenFOAM.so"
#1 Foam::sigFpe::sigHandler(int) in "/home/hsieh/OpenFOAM/OpenFOAM-2.1.x/platforms/linux64Gcc46DPOpt/lib/libOpenFOAM.so"
#2 in "/lib64/libc.so.6"
#3 FoamdICPreconditioner::calcReciprocalD(Foam::Field <double>&, Foam::lduMatrix const&) in "/home/hsieh/OpenFOAM/OpenFOAM-2.1.x/platforms/linux64Gcc46DPOpt/lib/libOpenFOAM.so"
#4 FoamdICPreconditionerdICPreconditioner(Foam::lduMa trix::solver const&, Foam::dictionary const&) in "/home/hsieh/OpenFOAM/OpenFOAM-2.1.x/platforms/linux64Gcc46DPOpt/lib/libOpenFOAM.so"
#5 Foam::lduMatrixpreconditioner::addsymMatrixConstru ctorToTable<FoamdICPreconditioner>::New(Foam::lduM atrix::solver const&, Foam::dictionary const&) in "/home/hsieh/OpenFOAM/OpenFOAM-2.1.x/platforms/linux64Gcc46DPOpt/lib/libOpenFOAM.so"
#6 Foam::lduMatrixpreconditioner::New(Foam::lduMatrix ::solver const&, Foam::dictionary const&) in "/home/hsieh/OpenFOAM/OpenFOAM-2.1.x/platforms/linux64Gcc46DPOpt/lib/libOpenFOAM.so"
#7 Foam::PCG::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const in "/home/hsieh/OpenFOAM/OpenFOAM-2.1.x/platforms/linux64Gcc46DPOpt/lib/libOpenFOAM.so"
#8 Foam::GAMGSolver::solveCoarsestLevel(Foam::Field<d ouble>&, Foam::Field<double> const&) const in "/home/hsieh/OpenFOAM/OpenFOAM-2.1.x/platforms/linux64Gcc46DPOpt/lib/libOpenFOAM.so"
#9 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::PtrList<Foam::Field<double> >&, Foam::PtrList<Foam::Field<double> >&, unsigned char) const in "/home/hsieh/OpenFOAM/OpenFOAM-2.1.x/platforms/linux64Gcc46DPOpt/lib/libOpenFOAM.so"
#10 Foam::GAMGSolver::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const in "/home/hsieh/OpenFOAM/OpenFOAM-2.1.x/platforms/linux64Gcc46DPOpt/lib/libOpenFOAM.so"
#11 Foam::fvMatrix<double>::solve(Foam::dictionary const&) in "/home/hsieh/OpenFOAM/OpenFOAM-2.1.x/platforms/linux64Gcc46DPOpt/lib/libfiniteVolume.so"
#12 Foam::fvMatrix<double>::solve() in "/home/hsieh/OpenFOAM/OpenFOAM-2.1.x/platforms/linux64Gcc46DPOpt/bin/chtMultiRegionSimpleFoam"
#13
in "/home/hsieh/OpenFOAM/OpenFOAM-2.1.x/platforms/linux64Gcc46DPOpt/bin/chtMultiRegionSimpleFoam"
#14 __libc_start_main in "/lib64/libc.so.6"
#15
at /home/abuild/rpmbuild/BUILD/glibc-2.15/csu/../sysdeps/x86_64/elf/start.S:116
Floating point exception


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