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-   -   GAMG solver causes troubles (http://www.cfd-online.com/Forums/openfoam-solving/88175-gamg-solver-causes-troubles.html)

colinB May 10, 2011 11:02

GAMG solver causes troubles
 
1 Attachment(s)
Hey there,

it has been a while since my last post here, but no working again with OF troubles come back ;)

my problem is the following error message that I encountered during my calculationon a hydrofoil:
(before that happens the number of iterations for solving the pressure reach their maximum)
Code:

#0  Foam::error::printStack(Foam::Ostream&) in "/opt/openfoam171/lib/linuxGccDPOpt/libOpenFOAM.so"
#1  Foam::sigFpe::sigFpeHandler(int) in "/opt/openfoam171/lib/linuxGccDPOpt/libOpenFOAM.so"
#2  Uninterpreted:
#3  Foam::GAMGSolver::scalingFactor(Foam::Field<double>&,  Foam::Field<double> const&, Foam::Field<double>  const&, Foam::Field<double> const&) const in  &quot;/opt/openfoam171/lib/linuxGccDPOpt/libOpenFOAM.so&quot;
#4  Foam::GAMGSolver::scalingFactor(Foam::Field<double>&,  Foam::lduMatrix const&, Foam::Field<double>&,  Foam::FieldField<Foam::Field, double> const&,  Foam::UPtrList<Foam::lduInterfaceField const> const&,  Foam::Field<double> const&, unsigned char) const in  &quot;/opt/openfoam171/lib/linuxGccDPOpt/libOpenFOAM.so&quot;
#5  Foam::GAMGSolver::Vcycle(Foam::PtrList<Foam::lduMatrix::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  &quot;/opt/openfoam171/lib/linuxGccDPOpt/libOpenFOAM.so&quot;
#6  Foam::GAMGSolver::solve(Foam::Field<double>&,  Foam::Field<double> const&, unsigned char) const in  &quot;/opt/openfoam171/lib/linuxGccDPOpt/libOpenFOAM.so&quot;
#7  Foam::fvMatrix<double>::solve(Foam::dictionary const&) in  &quot;/opt/openfoam171/lib/linuxGccDPOpt/libfiniteVolume.so&quot;
#8 
 in &quot;/opt/openfoam171/applications/bin/linuxGccDPOpt/interFoam&quot;
#9  __libc_start_main in &quot;/lib/tls/i686/cmov/libc.so.6&quot;
#10 
 in &quot;/opt/openfoam171/applications/bin/linuxGccDPOpt/interFoam&quot;

Unfortunately I have no clue what it means and also my search on google and here in the forum didn't gave me sufficient help.

Attached you find the case including the log file but wo results
so if you want to run it simply type:

blockMesh
setFields
interFoam

it is a rather simple case with ~ 110k cells

I guess the trouble comes from the &quot;special&quot; layer I introduced with alpha1=0.5 which I did for avoiding interference of a sharp changeover from the airInlet and waterInlet.
Eventually also the grid maybe troubling. But checkMesh accepts it.

parts of the log you see here (it doesn't fit into the case folder)

Code:


Courant Number mean: 0.000140728 max: 0.930393
Interface Courant Number mean: 3.19131e-06 max: 0.930393
deltaT = 1.32721e-05
Time = 0.458845

MULES: Solving for alpha1
Liquid phase volume fraction = 0.525029  Min(alpha1) = -1.20388  Max(alpha1) = 1.00001
MULES: Solving for alpha1
Liquid phase volume fraction = 0.525029  Min(alpha1) = -1.24572  Max(alpha1) = 1.00001
MULES: Solving for alpha1
Liquid phase volume fraction = 0.525029  Min(alpha1) = -1.28785  Max(alpha1) = 1.00001
MULES: Solving for alpha1
Liquid phase volume fraction = 0.525029  Min(alpha1) = -1.33024  Max(alpha1) = 1.00001
DILUPBiCG:  Solving for Ux, Initial residual = 0.0335748, Final residual = 8.67805e-13, No Iterations 2
DILUPBiCG:  Solving for Uz, Initial residual = 0.113298, Final residual = 2.72921e-07, No Iterations 1
GAMG:  Solving for p_rgh, Initial residual = 0.0649962, Final residual = 0.00032663, No Iterations 41
GAMG:  Solving for p_rgh, Initial residual = 0.000332293, Final residual = 3.24954e-06, No Iterations 100
GAMG:  Solving for p_rgh, Initial residual = 1.11011e-05, Final residual = 1.10477e-07, No Iterations 290
time step continuity errors : sum local = 1.88113e-11, global = -8.98642e-12, cumulative = -8.38788e-05
GAMG:  Solving for p_rgh, Initial residual = 0.0119578, Final residual = 8.14812e-05, No Iterations 2
GAMG:  Solving for p_rgh, Initial residual = 8.20786e-05, Final residual = 7.75983e-07, No Iterations 36
GAMG:  Solving for p_rgh, Initial residual = 1.38782e-06, Final residual = 1.31951e-08, No Iterations 137
time step continuity errors : sum local = 9.66489e-12, global = -8.98642e-12, cumulative = -8.38788e-05
GAMG:  Solving for p_rgh, Initial residual = 0.00137856, Final residual = 2.8292e-06, No Iterations 2
GAMG:  Solving for p_rgh, Initial residual = 3.04841e-06, Final residual = 2.87014e-08, No Iterations 102
GAMG:  Solving for p_rgh, Initial residual = 2.43316e-07, Final residual = 9.43905e-09, No Iterations 231
time step continuity errors : sum local = 8.99151e-12, global = -8.98642e-12, cumulative = -8.38788e-05
GAMG:  Solving for p_rgh, Initial residual = 0.000148687, Final residual = 6.88212e-07, No Iterations 1
GAMG:  Solving for p_rgh, Initial residual = 8.41732e-07, Final residual = 9.84476e-09, No Iterations 253
GAMG:  Solving for p_rgh, Initial residual = 2.06668e-07, Final residual = 9.83106e-09, No Iterations 236
time step continuity errors : sum local = 9.00801e-12, global = -8.98642e-12, cumulative = -8.38788e-05
ExecutionTime = 2818.28 s  ClockTime = 2862 s

Courant Number mean: 0.000127959 max: 0.844884
Interface Courant Number mean: 4.37856e-06 max: 0.844884
deltaT = 1.25508e-05
Time = 0.458858

MULES: Solving for alpha1
Liquid phase volume fraction = 0.525029  Min(alpha1) = -1.31119  Max(alpha1) = 1.00001
MULES: Solving for alpha1
Liquid phase volume fraction = 0.525029  Min(alpha1) = -1.2924  Max(alpha1) = 1.00001
MULES: Solving for alpha1
Liquid phase volume fraction = 0.525029  Min(alpha1) = -1.27387  Max(alpha1) = 1.00001
MULES: Solving for alpha1
Liquid phase volume fraction = 0.525029  Min(alpha1) = -1.25562  Max(alpha1) = 1.00001
DILUPBiCG:  Solving for Ux, Initial residual = 0.0169796, Final residual = 1.86494e-07, No Iterations 1
DILUPBiCG:  Solving for Uz, Initial residual = 0.080901, Final residual = 4.03905e-11, No Iterations 2
GAMG:  Solving for p_rgh, Initial residual = 0.311232, Final residual = 0.00210653, No Iterations 3
GAMG:  Solving for p_rgh, Initial residual = 0.00227784, Final residual = 1.54957e-05, No Iterations 11
GAMG:  Solving for p_rgh, Initial residual = 3.70093e-05, Final residual = 2.54066e-07, No Iterations 11
time step continuity errors : sum local = 2.12385e-11, global = -7.17953e-12, cumulative = -8.38788e-05
GAMG:  Solving for p_rgh, Initial residual = 0.109349, Final residual = 0.00081582, No Iterations 4
GAMG:  Solving for p_rgh, Initial residual = 0.000898281, Final residual = 7.66732e-06, No Iterations 12
GAMG:  Solving for p_rgh, Initial residual = 3.44177e-05, Final residual = 2.52469e-07, No Iterations 9
time step continuity errors : sum local = 1.23284e-11, global = -7.17953e-12, cumulative = -8.38788e-05
GAMG:  Solving for p_rgh, Initial residual = 0.0671865, Final residual = 0.00060329, No Iterations 4
GAMG:  Solving for p_rgh, Initial residual = 0.000683255, Final residual = 6.25839e-06, No Iterations 12
GAMG:  Solving for p_rgh, Initial residual = 3.07815e-05, Final residual = 3.06285e-07, No Iterations 8
time step continuity errors : sum local = 1.38091e-11, global = -7.17953e-12, cumulative = -8.38788e-05
GAMG:  Solving for p_rgh, Initial residual = 0.0652599, Final residual = 0.000571597, No Iterations 4
GAMG:  Solving for p_rgh, Initial residual = 0.000580785, Final residual = 5.32414e-06, No Iterations 12
GAMG:  Solving for p_rgh, Initial residual = 2.36578e-05, Final residual = 2.32577e-07, No Iterations 8
time step continuity errors : sum local = 2.1247e-11, global = -7.17953e-12, cumulative = -8.38788e-05
ExecutionTime = 2828.13 s  ClockTime = 2872 s

Courant Number mean: 0.000124125 max: 0.921853
Interface Courant Number mean: 3.42458e-06 max: 0.921853
deltaT = 1.08773e-05
Time = 0.458869

MULES: Solving for alpha1
Liquid phase volume fraction = 0.525029  Min(alpha1) = -1.28124  Max(alpha1) = 1.00001
MULES: Solving for alpha1
Liquid phase volume fraction = 0.525029  Min(alpha1) = -1.30668  Max(alpha1) = 1.00001
MULES: Solving for alpha1
Liquid phase volume fraction = 0.525029  Min(alpha1) = -1.33194  Max(alpha1) = 1.00001
MULES: Solving for alpha1
Liquid phase volume fraction = 0.525029  Min(alpha1) = -1.35701  Max(alpha1) = 1.00001
DILUPBiCG:  Solving for Ux, Initial residual = 0.0362697, Final residual = 3.75729e-07, No Iterations 1
DILUPBiCG:  Solving for Uz, Initial residual = 0.118264, Final residual = 8.8751e-07, No Iterations 1
GAMG:  Solving for p_rgh, Initial residual = 0.109203, Final residual = 2.88085e+32, No Iterations 1000
GAMG:  Solving for p_rgh, Initial residual = 0.239738, Final residual = 1.58254e+33, No Iterations 1000
GAMG:  Solving for p_rgh, Initial residual = 0.239738, Final residual = 1.58254e+33, No Iterations 1000
time step continuity errors : sum local = 3.92821e+95, global = -2.13933e+79, cumulative = -2.13933e+79
GAMG:  Solving for p_rgh, Initial residual = 0.336348, Final residual = 3.22301e+33, No Iterations 1000

I hope I provided all information you need, if not let me know.
I appreciate your help

regards Colin

mvoss May 11, 2011 11:42

How can alpha1 become negative ?
Did you also tried another solver ?

colinB May 11, 2011 12:31

good question! I don't know! Some deviations are nornmal in my Opinion ( I sometimes encounter min alpha1 10e-200 or so wich I consider to be zero)
But that big negativ deviations I haven't seen before (actually I just recognized)

no I haven't! any suggestions for different solvers?

immortality January 26, 2013 16:57

hi.could you send me your GAMG solver to me?
Thanks.

laurent98 June 13, 2013 02:48

hi Colin,
did you solve this problem? because i got the same kind of alpha growing to much
alpha going to 7 then 13. then crach..
also on a hydrofoil...
thank you LL

immortality June 13, 2013 08:48

Colin change your scheme to limited schemes and reduce time step.


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