[ce73stargazer]

Hi there I was doing a simulation, but it stopped at 0.6s

and Here is the error message.

Courant Number mean: 0.000504797 max: 0.0973274
Interface Courant Number mean: 8.63921e-05 max: 0.0971525
deltaT = 0.00134568
Time = 0.642048

PIMPLE: iteration 1
smoothSolver: Solving for alpha.water, Initial residual = 0.000141556, Final residual = 0.00366667, No Iterations 1000
Phase-1 volume fraction = 24.2481 Min(alpha.water) = -30932.7 Max(alpha.water) = 37042.5
MULES: Correcting alpha.water
Phase-1 volume fraction = 24.2481 Min(alpha.water) = -30808.8 Max(alpha.water) = 35350.9
Relaxing time: 0.06 s
DILUPBiCG: Solving for Ux, Initial residual = 0.0303599, Final residual = 1.51651e-10, No Iterations 2
DILUPBiCG: Solving for Uy, Initial residual = 0.00779237, Final residual = 4.83248e-11, No Iterations 2
GAMG: Solving for p_rgh, Initial residual = 0.000124016, Final residual = 7.2175e-08, No Iterations 4
GAMG: Solving for p_rgh, Initial residual = 7.81753e-08, Final residual = 7.81753e-08, No Iterations 0
time step continuity errors : sum local = 2.0307e-08, global = 2.70661e-09, cumulative = 1.69335e-07
GAMG: Solving for p_rgh, Initial residual = 5.10141e-06, Final residual = 7.67331e-08, No Iterations 5
GAMG: Solving for p_rgh, Initial residual = 1.74342e-07, Final residual = 7.47705e-08, No Iterations 2
time step continuity errors : sum local = 8.92567e-09, global = 4.20014e-10, cumulative = 1.69755e-07
GAMG: Solving for p_rgh, Initial residual = 2.60283e-05, Final residual = 9.52378e-08, No Iterations 9
GAMG: Solving for p_rgh, Initial residual = 2.30742e-08, Final residual = 8.87715e-09, No Iterations 2
time step continuity errors : sum local = 5.36728e-09, global = 5.2285e-10, cumulative = 1.70278e-07
ExecutionTime = 2759.53 s ClockTime = 2802 s

Courant Number mean: 0.000623217 max: 1.72889
Interface Courant Number mean: 0.000106421 max: 1.70611
deltaT = 0.000194539
Time = 0.642243

PIMPLE: iteration 1
smoothSolver: Solving for alpha.water, Initial residual = 2.42692e-05, Final residual = 0.00102413, No Iterations 1000
Phase-1 volume fraction = 24.3986 Min(alpha.water) = -30681 Max(alpha.water) = 35284.4
MULES: Correcting alpha.water
Phase-1 volume fraction = 24.3986 Min(alpha.water) = -30676.1 Max(alpha.water) = 34308.2
Relaxing time: 0.06 s
DILUPBiCG: Solving for Ux, Initial residual = 0.0464786, Final residual = 1.6925e-11, No Iterations 2
DILUPBiCG: Solving for Uy, Initial residual = 0.00715005, Final residual = 4.43512e-13, No Iterations 2
[1] #0 Foam::error:rintStack(Foam::Ostream&) at ??:?
[1] #1 Foam::sigFpe::sigHandler(int) at ??:?
[1] #2 ? in "/lib/x86_64-linux-gnu/libc.so.6"
[1] #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 ??:?
[1] #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 ??:?
[1] #5 Foam::GAMGSolver::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const at ??:?
[1] #6 Foam::fvMatrix<double>::solveSegregated(Foam::dict ionary const&) at ??:?
[1] #7 Foam::fvMatrix<double>::solve(Foam::dictionary const&) at ??:?
[1] #8 main at ??:?
[1] #9 __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6"
[1] #10 ? at ??:?
[ubuntu14:21890] *** Process received signal ***
[ubuntu14:21890] Signal: Floating point exception (8)
[ubuntu14:21890] Signal code: (-6)
[ubuntu14:21890] Failing at address: 0x3e800005582
[ubuntu14:21890] [ 0] /lib/x86_64-linux-gnu/libc.so.6(+0x36cb0) [0x7f8837233cb0]
[ubuntu14:21890] [ 1] /lib/x86_64-linux-gnu/libc.so.6(gsignal+0x37) [0x7f8837233c37]
[ubuntu14:21890] [ 2] /lib/x86_64-linux-gnu/libc.so.6(+0x36cb0) [0x7f8837233cb0]
[ubuntu14:21890] [ 3] /opt/openfoam240/platforms/linux64GccDPOpt/lib/libOpenFOAM.so(_ZNK4Foam10GAMGSolver5scaleERNS_5Fi eldIdEES3_RKNS_9lduMatrixERKNS_10FieldFieldIS1_dEE RKNS_8UPtrListIKNS_17lduInterfaceFieldEEERKS2_h+0x cd) [0x7f8838388b8d]
[ubuntu14:21890] [ 4] /opt/openfoam240/platforms/linux64GccDPOpt/lib/libOpenFOAM.so(_ZNK4Foam10GAMGSolver6VcycleERKNS_7 PtrListINS_9lduMatrix8smootherEEERNS_5FieldIdEERKS 8_S9_S9_S9_S9_S9_RNS1_IS8_EESD_h+0xfe9) [0x7f883838c1e9]
[ubuntu14:21890] [ 5] /opt/openfoam240/platforms/linux64GccDPOpt/lib/libOpenFOAM.so(_ZNK4Foam10GAMGSolver5solveERNS_5Fi eldIdEERKS2_h+0x4ae) [0x7f883838e00e]
[ubuntu14:21890] [ 6] /opt/openfoam240/platforms/linux64GccDPOpt/lib/libfiniteVolume.so(_ZN4Foam8fvMatrixIdE15solveSegr egatedERKNS_10dictionaryE+0x132) [0x7f883acf5c32]
[ubuntu14:21890] [ 7] waveFoam(_ZN4Foam8fvMatrixIdE5solveERKNS_10diction aryE+0x108) [0x47b5a8]
[ubuntu14:21890] [ 8] waveFoam(main+0x531a) [0x430f5a]
[ubuntu14:21890] [ 9] /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf5) [0x7f883721ef45]
[ubuntu14:21890] [10] waveFoam() [0x43563b]
[ubuntu14:21890] *** End of error message ***
--------------------------------------------------------------------------
mpirun noticed that process rank 1 with PID 21890 on node ubuntu14.04 exited on signal 8 (Floating point exception).
--------------------------------------------------------------------------
zhifang@ubuntu14:~/OpenFoamTests/peter$

Can I conclude that the simulation get dumped because the max Courant Number is bigger than 1?

[teuk]

Hi ce73stargazer,

Originally Posted by ce73stargazer

Can I conclude that the simulation get dumped because the max Courant Number is bigger than 1?

Would be my first suggestion. It crashes by solving your p_rgh-field...

regards,
teuk

[vikramaditya91]

I am not really experienced with multiphase simulations on OpneFOAM, but I hear from experts that the maxCo should be under 0.5 or sometimes even under 0.1.

[MBttR]

Originally Posted by vikramaditya91

I am not really experienced with multiphase simulations on OpneFOAM, but I hear from experts that the maxCo should be under 0.5 or sometimes even under 0.1.

I think <1 should be fine, so that it passes through each cell. The OF tutorials on heatTransfer do have maxCo set to 0.6 or 0.7.

[ce73stargazer]

Originally Posted by MBttR

I think <1 should be fine, so that it passes through each cell. The OF tutorials on heatTransfer do have maxCo set to 0.6 or 0.7.

Hi there, after some triggers around the mesh, I still have the same error even the maximum Courant number is smaller than 1 and one more concern is that the Courant number gradually increases. Any suggestions on this increase?

time step continuity errors : sum local = 2.00357e-08, global = 4.86459e-09, cumulative = -1.54075e-08
GAMG: Solving for p_rgh, Initial residual = 3.98566e-08, Final residual = 3.98566e-08, No Iterations 0
GAMG: Solving for p_rgh, Initial residual = 3.98566e-08, Final residual = 6.6172e-09, No Iterations 1
time step continuity errors : sum local = 6.94184e-09, global = 2.62189e-09, cumulative = -1.27856e-08
ExecutionTime = 8817.21 s ClockTime = 8903 s

Courant Number mean: 2.05474e-05 max: 0.17935
Interface Courant Number mean: 2.76556e-06 max: 0.0343659
deltaT = 0.000181727
Time = 0.409933

PIMPLE: iteration 1
smoothSolver: Solving for alpha.water, Initial residual = 0.0041067, Final residual = 0.0369398, No Iterations 1000
Phase-1 volume fraction = 12.7913 Min(alpha.water) = -4.66658e+07 Max(alpha.water) = 4.67924e+07
MULES: Correcting alpha.water
Phase-1 volume fraction = 12.7913 Min(alpha.water) = -1.39269e+08 Max(alpha.water) = 1.39005e+08
Relaxing time: 0.02 s
DILUPBiCG: Solving for Ux, Initial residual = 0.219862, Final residual = 1.02471e-10, No Iterations 5
DILUPBiCG: Solving for Uy, Initial residual = 0.0921702, Final residual = 2.59232e-13, No Iterations 6
GAMG: Solving for p_rgh, Initial residual = 2.546e-06, Final residual = 6.36149e-08, No Iterations 1
GAMG: Solving for p_rgh, Initial residual = 9.05105e-08, Final residual = 9.05105e-08, No Iterations 0
time step continuity errors : sum local = 9.6477e-08, global = 4.15922e-09, cumulative = -8.62636e-09
[7] #0 Foam::error:rintStack(Foam::Ostream&) in "/opt/OpenFOAM/OpenFOAM-2.4.0/platforms/linux64GccDPOpt/lib/libOpenFOAM.so"
[7] #1 Foam::sigFpe::sigHandler(int) in "/opt/OpenFOAM/OpenFOAM-2.4.0/platforms/linux64GccDPOpt/lib/libOpenFOAM.so"
[7] #2 ? in "/lib64/libc.so.6"
[7] #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 in "/opt/OpenFOAM/OpenFOAM-2.4.0/platforms/linux64GccDPOpt/lib/libOpenFOAM.so"
[7] #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 in "/opt/OpenFOAM/OpenFOAM-2.4.0/platforms/linux64GccDPOpt/lib/libOpenFOAM.so"
[7] #5 Foam::GAMGSolver::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const in "/opt/OpenFOAM/OpenFOAM-2.4.0/platforms/linux64GccDPOpt/lib/libOpenFOAM.so"
[7] #6 Foam::fvMatrix<double>::solveSegregated(Foam::dict ionary const&) in "/opt/OpenFOAM/OpenFOAM-2.4.0/platforms/linux64GccDPOpt/lib/libfiniteVolume.so"
[7] #7 Foam::fvMatrix<double>::solve(Foam::dictionary const&) at ??:?
[7] #8 ? at ??:?
[7] #9 __libc_start_main in "/lib64/libc.so.6"
[7] #10 ? at ??:?
[mango:50004] *** Process received signal ***
[mango:50004] Signal: Floating point exception (8)
[mango:50004] Signal code: (-6)
[mango:50004] Failing at address: 0xf40550000c354
[mango:50004] [ 0] /lib64/libc.so.6(+0x35670) [0x7f808611f670]
[mango:50004] [ 1] /lib64/libc.so.6(gsignal+0x37) [0x7f808611f5f7]
[mango:50004] [ 2] /lib64/libc.so.6(+0x35670) [0x7f808611f670]
[mango:50004] [ 3] /opt/OpenFOAM/OpenFOAM-2.4.0/platforms/linux64GccDPOpt/lib/libOpenFOAM.so(_ZNK4Foam10GAMGSolver5scaleERNS_5Fi eldIdEES3_RKNS_9lduMatrixERKNS_10FieldFieldIS1_dEE RKNS_8UPtrListIKNS_17lduInterfaceFieldEEERKS2_h+0x ba) [0x7f8087271aaa]
[mango:50004] [ 4] /opt/OpenFOAM/OpenFOAM-2.4.0/platforms/linux64GccDPOpt/lib/libOpenFOAM.so(_ZNK4Foam10GAMGSolver6VcycleERKNS_7 PtrListINS_9lduMatrix8smootherEEERNS_5FieldIdEERKS 8_S9_S9_S9_S9_S9_RNS1_IS8_EESD_h+0x222d) [0x7f808727635d]
[mango:50004] [ 5] /opt/OpenFOAM/OpenFOAM-2.4.0/platforms/linux64GccDPOpt/lib/libOpenFOAM.so(_ZNK4Foam10GAMGSolver5solveERNS_5Fi eldIdEERKS2_h+0x4ae) [0x7f8087276f3e]
[mango:50004] [ 6] /opt/OpenFOAM/OpenFOAM-2.4.0/platforms/linux64GccDPOpt/lib/libfiniteVolume.so(_ZN4Foam8fvMatrixIdE15solveSegr egatedERKNS_10dictionaryE+0x132) [0x7f8089b65c22]
[mango:50004] [ 7] waveFoam(_ZN4Foam8fvMatrixIdE5solveERKNS_10diction aryE+0x108) [0x47b378]
[mango:50004] [ 8] waveFoam() [0x430d3a]
[mango:50004] [ 9] /lib64/libc.so.6(__libc_start_main+0xf5) [0x7f808610bb15]
[mango:50004] [10] waveFoam() [0x43541d]
[mango:50004] *** End of error message ***
--------------------------------------------------------------------------
mpirun noticed that process rank 7 with PID 50004 on node mango.eait.uq.edu.au exited on signal 8 (Floating point exception).

[MBttR]

What exactly are you trying to solve? You could try a different solver for p in stead of GAMG, such as PCG.

[teuk]

Hi ce73stargazer,

smoothSolver: Solving for alpha.water, Initial residual = 0.0041067, Final residual = 0.0369398, No Iterations 1000

It looks like your solver is not capable to solve the water fraction. (final Res > initial Res; max iterations)

Can't tell you why...

one more concern is that the Courant number gradually increases

If it's not converging over time, moreover increases more or less in constant steps this is an indicator for a not converging solution. What does it mean? There is at least one cell in your mesh where the velocity is increasing all the time. Maybe a mesh problem...


regards,
teuk

[ce73stargazer]

Originally Posted by teuk

Hi ce73stargazer,

It looks like your solver is not capable to solve the water fraction. (final Res > initial Res; max iterations)

Can't tell you why...


If it's not converging over time, moreover increases more or less in constant steps this is an indicator for a not converging solution. What does it mean? There is at least one cell in your mesh where the velocity is increasing all the time. Maybe a mesh problem...


regards,
teuk

Hi teuk

Thanks for the reply, I do believe its the mesh's problem. Thats why what i did initially is changing the dx size to make the Courant number small, however, that doesnot work either.

here is the output of the checkMesh

/*---------------------------------------------------------------------------*\
| ========= | |
| \\ / F ield | foam-extend: Open Source CFD |
| \\ / O peration | Version: 3.1 |
| \\ / A nd | Web: http://www.extend-project.de |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
Build : 3.1-1dd681f6e943
Exec : checkMesh
Date : Aug 01 2016
Time : 08:59:18
Host : ubuntu14.04
PID : 3217
CtrlDict : /home/zhifang/foam/foam-extend-3.1/etc/controlDict
Case : /home/zhifang/HPC/SHORELINE
nProcs : 1
SigFpe : Enabling floating point exception trapping (FOAM_SIGFPE).

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
Create time

Create polyMesh for time = 0


From function void polyMesh::initMesh()
in file meshes/polyMesh/polyMeshInitMesh.C at line 81
Truncating neighbour list at 2693775 for backward compatibility
Time = 0

Mesh stats
all points: 2712452
live points: 2712452
all faces: 5406225
live faces: 5406225
internal faces: 2693775
cells: 1350000
boundary patches: 6
point zones: 0
face zones: 0
cell zones: 0

Overall number of cells of each type:
hexahedra: 1350000
prisms: 0
wedges: 0
pyramids: 0
tet wedges: 0
tetrahedra: 0
polyhedra: 0

Checking topology...
Boundary definition OK.
Point usage OK.
Upper triangular ordering OK.
Face vertices OK.
Number of regions: 1 (OK).

Checking patch topology for multiply connected surfaces ...
Patch Faces Points Area [m^2] Surface topology
front 1350000 1356226 7.28e+06 ok (non-closed singly connected)
back 1350000 1356226 7.28e+06 ok (non-closed singly connected)
inlet 225 452 6.3 ok (non-closed singly connected)
beach 225 452 0.6 ok (non-closed singly connected)
atmosphere 6000 12002 1800 ok (non-closed singly connected)
bottom 6000 12002 1800.01 ok (non-closed singly connected)

Checking geometry...
This is a 2-D mesh
Overall domain bounding box (0 -200 -0.015) (60000 10 0.015)
Mesh (non-empty, non-wedge) directions (1 1 0)
Mesh (non-empty) directions (1 1 0)
Mesh (non-empty, non-wedge) dimensions 2
All edges aligned with or perpendicular to non-empty directions.
Boundary openness (2.96485e-20 5.69458e-21 1.82924e-13) Threshold = 1e-06 OK.
Max cell openness = 2.64406e-16 OK.
Max aspect ratio = 497.585 OK.
Minumum face area = 0.000602912. Maximum face area = 20.0971. Face area magnitudes OK.
Min volume = 0.00602912. Max volume = 0.602912. Total volume = 218400. Cell volumes OK.
Mesh non-orthogonality Max: 0.849574 average: 0.0869687 Threshold = 70
Non-orthogonality check OK.
Face pyramids OK.
Max skewness = 0.00310929 OK.

Mesh OK.

End

I really cant tell what's the problem with it..Any suggestions?

[teuk]

Hi ce73stargazer,

Your chekMesh is looking really nice to me besides your aspect ratio. But I think this is not the problem here. You should try to write your solution for the last time steps when it crashes beginning from moderate courant-number to blow up. If you investigate your fields over time in some postprocessing-software (f.e paraview) you should be able to find the cell(s) which causes the trouble. There sould be one or a few cells where your p- or U-fields show an unexpected behaviour.


regards,
teuk