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 sivakumar March 15, 2013 13:49

calculation stops after few time steps

Hi Guys,
I am facing strange problem for last one week, I am using MRFSimpleFoam, I am simulating axial fan.

I am using GAMBIT for meshing.

I am using one passage of the fan, with hybrid mesh.

I have successfully simulated one case with good results.

when I tried to do grid check, I changed the mesh in to 4.5 million cells.
The geometry and boundary condition everything is same except mesh size, There I am facing epsilon bounding problem, and time step continuity increasing, after few time step the calculation not moving further.
I tried the following steps to solve my problem,

i) for epsilon bounding problem -- > divSchemes --> div(phi,epsilon) Gauss upwind;

but no use, still epsilon is bounding.

ii) time step continuity error -- > fvSolution -- P --> reltol -->0.005

no change in the simulation,

iii) I checked the yPlus, it looks fine:

Patch 1 named top2 y+ : min: 58.8464 max: 78.8647 average: 73.7851

Patch 2 named top1 y+ : min: 27.2827 max: 91.6556 average: 48.7005

Patch 3 named top0 y+ : min: 62.2679 max: 78.8773 average: 74.4014

Patch 4 named center1 y+ : min: 51.1635 max: 64.7924 average: 61.8537

Patch 5 named fan y+ : min: 28.5618 max: 99.464 average: 47.9173

Patch 6 named center0 y+ : min: 62.5154 max: 70.3021 average: 65.0959

iv) I tried k-epsilon and kOmegaSST none of them is working,

v) CheckMesh

Create time

Create polyMesh for time = 0

Time = 0

Mesh stats
points: 1739434
faces: 8687515
internal faces: 8536569
cells: 3491346
boundary patches: 16
point zones: 0
face zones: 1
cell zones: 2

Overall number of cells of each type:
hexahedra: 0
prisms: 3258700
wedges: 0
pyramids: 0
tet wedges: 0
tetrahedra: 232646
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 Surface topology
outlet 4468 2324 ok (non-closed singly connected)
top2 35990 36642 ok (non-closed singly connected)
top1 2877 1535 ok (non-closed singly connected)
top0 8540 8742 ok (non-closed singly connected)
center1 14750 15366 ok (non-closed singly connected)
fan 5016 2659 ok (non-closed singly connected)
center0 3360 3525 ok (non-closed singly connected)
inlet 4447 2317 ok (non-closed singly connected)
ILR0 7000 7191 ok (non-closed singly connected)
ILR1 7000 7191 ok (non-closed singly connected)
OLR0 27140 27777 ok (non-closed singly connected)
OLR1 27140 27777 ok (non-closed singly connected)
CLR0 795 455 ok (non-closed singly connected)
CLR1 795 455 ok (non-closed singly connected)
FCLR0 814 462 ok (non-closed singly connected)
FCLR1 814 462 ok (non-closed singly connected)

Checking geometry...
Overall domain bounding box (0.217015 -0.543554 -1.5) (0.771 0.158713 6)
Mesh (non-empty, non-wedge) directions (1 1 1)
Mesh (non-empty) directions (1 1 1)
Boundary openness (-2.48875e-14 1.40014e-13 7.74113e-17) OK.
Max cell openness = 3.24529e-16 OK.
Max aspect ratio = 15.6835 OK.
Minumum face area = 2.13538e-06. Maximum face area = 0.000141986. Face area magnitudes OK.
Min volume = 2.92584e-09. Max volume = 6.74344e-07. Total volume = 1.47216. Cell volumes OK.
Mesh non-orthogonality Max: 82.8897 average: 5.76063
*Number of severely non-orthogonal faces: 99.
Non-orthogonality check OK.
<<Writing 99 non-orthogonal faces to set nonOrthoFaces
Face pyramids OK.
Max skewness = 2.35351 OK.
Coupled point location match (average 0.000113918) OK.

Mesh OK.

End

solver output:
it stoped moving at 5 th time step

Starting time loop

Time = 1

smoothSolver: Solving for Ux, Initial residual = 1, Final residual = 0.00571946, No Iterations 4
smoothSolver: Solving for Uy, Initial residual = 1, Final residual = 0.00556588, No Iterations 4
smoothSolver: Solving for Uz, Initial residual = 1, Final residual = 0.00736422, No Iterations 6
GAMG: Solving for p, Initial residual = 1, Final residual = 0.0441907, No Iterations 38
GAMG: Solving for p, Initial residual = 0.012071, Final residual = 0.00021857, No Iterations 2
GAMG: Solving for p, Initial residual = 0.00250672, Final residual = 5.80544e-05, No Iterations 3
time step continuity errors : sum local = 0.134507, global = 0.0245819, cumulative = 0.0245819
smoothSolver: Solving for epsilon, Initial residual = 0.103833, Final residual = 9.1326e-05, No Iterations 4
bounding epsilon, min: -3.54789 max: 80.4213 average: 0.993169
smoothSolver: Solving for k, Initial residual = 1, Final residual = 0.00974666, No Iterations 4
ExecutionTime = 60.77 s ClockTime = 61 s

Time = 2

smoothSolver: Solving for Ux, Initial residual = 0.482585, Final residual = 0.00156254, No Iterations 8
smoothSolver: Solving for Uy, Initial residual = 0.513851, Final residual = 0.00198613, No Iterations 8
smoothSolver: Solving for Uz, Initial residual = 0.973847, Final residual = 0.00548264, No Iterations 8
GAMG: Solving for p, Initial residual = 0.00722092, Final residual = 0.000359208, No Iterations 5
GAMG: Solving for p, Initial residual = 0.0103071, Final residual = 0.00025249, No Iterations 2
GAMG: Solving for p, Initial residual = 0.00168303, Final residual = 8.27458e-05, No Iterations 3
time step continuity errors : sum local = 0.0521777, global = -0.00277576, cumulative = 0.0218062
smoothSolver: Solving for epsilon, Initial residual = 0.162637, Final residual = 0.000535318, No Iterations 4
bounding epsilon, min: -85.4964 max: 53189.4 average: 4.97721
smoothSolver: Solving for k, Initial residual = 0.673913, Final residual = 0.00405384, No Iterations 4
ExecutionTime = 91.03 s ClockTime = 92 s

Time = 3

smoothSolver: Solving for Ux, Initial residual = 0.186656, Final residual = 0.000928521, No Iterations 4
smoothSolver: Solving for Uy, Initial residual = 0.230005, Final residual = 0.000341969, No Iterations 2
smoothSolver: Solving for Uz, Initial residual = 0.30883, Final residual = 0.000804547, No Iterations 6
GAMG: Solving for p, Initial residual = 0.0158289, Final residual = 0.000679748, No Iterations 24
GAMG: Solving for p, Initial residual = 0.994707, Final residual = 0.0375188, No Iterations 3
GAMG: Solving for p, Initial residual = 0.244631, Final residual = 0.0080995, No Iterations 3
time step continuity errors : sum local = 1.23811e+06, global = 55.2375, cumulative = 55.2593
smoothSolver: Solving for epsilon, Initial residual = 0.999999, Final residual = 0.00488149, No Iterations 4
smoothSolver: Solving for k, Initial residual = 1, Final residual = 0.00568028, No Iterations 4
ExecutionTime = 131.68 s ClockTime = 133 s

Time = 4

smoothSolver: Solving for Ux, Initial residual = 0.635494, Final residual = 0.00550478, No Iterations 4
smoothSolver: Solving for Uy, Initial residual = 0.545846, Final residual = 0.001546, No Iterations 4
smoothSolver: Solving for Uz, Initial residual = 0.506895, Final residual = 0.00203654, No Iterations 4
GAMG: Solving for p, Initial residual = 0.999569, Final residual = 0.0489144, No Iterations 703
GAMG: Solving for p, Initial residual = 9.25062e-08, Final residual = 9.919e-09, No Iterations 513
GAMG: Solving for p, Initial residual = 5.71199e-05, Final residual = 2.46643e-08, No Iterations 1
time step continuity errors : sum local = 7.14548e+11, global = -4.74329e+10, cumulative = -4.74329e+10
smoothSolver: Solving for epsilon, Initial residual = 0.999748, Final residual = 7.93481e-05, No Iterations 4
smoothSolver: Solving for k, Initial residual = 1, Final residual = 0.00500452, No Iterations 2
ExecutionTime = 742.01 s ClockTime = 745 s

Time = 5

smoothSolver: Solving for Ux, Initial residual = 0.967222, Final residual = 0.00860478, No Iterations 4
smoothSolver: Solving for Uy, Initial residual = 0.961546, Final residual = 0.00797491, No Iterations 4
smoothSolver: Solving for Uz, Initial residual = 0.961858, Final residual = 0.00706433, No Iterations 4

I have no clue about the problem,

Thank you very much for your time and help,

Thanks,
Sivakumar

 doubtsincfd March 15, 2013 14:24

Its stopping while solving for p, and you have high continuity errors which usually go together.

Were you having same non-orthogonality before? Are the two meshes of comparable quality?

Try under-relaxing more. What are your relaxation factors?

Can you also post the schemes you are using?

 sivakumar March 15, 2013 15:56

Hi Champhekar,

For your first question : yes,

Due to high skewness the check mesh has been failed, but the case is running as well I got good results.

Create time

Create polyMesh for time = 0

Time = 0

Mesh stats
points: 3229772
faces: 9489336
internal faces: 9291864
cells: 3130200
boundary patches: 16
point zones: 0
face zones: 1
cell zones: 1

Overall number of cells of each type:
hexahedra: 3130200
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 Surface topology
top2 29000 29559 ok (non-closed singly connected)
top1 2536 2647 ok (non-closed singly connected)
top0 10200 10419 ok (non-closed singly connected)
outlet 4350 4484 ok (non-closed singly connected)
inlet 5100 5244 ok (non-closed singly connected)
center1 29000 29559 ok (non-closed singly connected)
fan 6586 6847 ok (non-closed singly connected)
center0 10200 10419 ok (non-closed singly connected)
ILR0 11250 11476 ok (non-closed singly connected)
ILR1 11250 11476 ok (non-closed singly connected)
OLR0 37500 38076 ok (non-closed singly connected)
OLR1 37500 38076 ok (non-closed singly connected)
CLR0 750 836 ok (non-closed singly connected)
CLR1 750 836 ok (non-closed singly connected)
FCLR0 750 836 ok (non-closed singly connected)
FCLR1 750 836 ok (non-closed singly connected)

Checking geometry...
Overall domain bounding box (0.0758611 -0.00381591 -1.5) (0.771091 0.642452 6)
Mesh (non-empty, non-wedge) directions (1 1 1)
Mesh (non-empty) directions (1 1 1)
Boundary openness (-1.07228e-14 1.69542e-15 7.94528e-17) OK.
Max cell openness = 3.54673e-16 OK.
Max aspect ratio = 14.6389 OK.
Minumum face area = 1.53323e-06. Maximum face area = 0.000256597. Face area magnitudes OK.
Min volume = 9.44895e-09. Max volume = 1.58035e-06. Total volume = 1.47172. Cell volumes OK.
Mesh non-orthogonality Max: 79.8654 average: 10.9221
*Number of severely non-orthogonal faces: 7098.
Non-orthogonality check OK.
<<Writing 7098 non-orthogonal faces to set nonOrthoFaces
Face pyramids OK.
***Max skewness = 5.53165, 62 highly skew faces detected which may impair the quality of the results
<<Writing 62 skew faces to set skewFaces
Coupled point location match (average 1.89162e-09) OK.

Failed 1 mesh checks.

End

For your second question: yes, I think the new mesh is better than old one.

my relaxing factors are:
epsilon --> 0.5
k--> 0.5
U -->0.7
p --> 0.2

fvSchemes is:

ddtSchemes
{
}

{
default Gauss linear;
}

divSchemes
{
default none;
div(phi,U) Gauss linear;
div(phi,k) Gauss upwind;
div(phi,omega) Gauss upwind;
div(phi,epsilon) Gauss upwind;
}

laplacianSchemes
{
default Gauss linear corrected;
}

interpolationSchemes
{
default linear;
interpolate(U) linear;
}

{
default corrected;
}

fluxRequired
{
default no;
p ;
}

fvSolution:

solvers
{
p
{
solver GAMG;
tolerance 1e-08;
relTol 0.005;
smoother GaussSeidel;
nPreSweeps 0;
nPostSweeps 2;
cacheAgglomeration true;
nCellsInCoarsestLevel 20;
agglomerator faceAreaPair;
mergeLevels 1;
}

U
{
solver smoothSolver;
smoother GaussSeidel;
nSweeps 2;
tolerance 1e-07;
relTol 0.01;
minIter 1;
maxIter 1000;
}

k
{
solver smoothSolver;
smoother GaussSeidel;
nSweeps 2;
tolerance 1e-07;
relTol 0.01;
minIter 1;
maxIter 1000;
}

omega
{
solver smoothSolver;
smoother GaussSeidel;
tolerance 1e-7;
relTol 0.01;
nSweeps 1;
minIter 1;
maxIter 1000;
}

epsilon
{
solver smoothSolver;
smoother GaussSeidel;
nSweeps 2;
tolerance 1e-07;
relTol 0.01;
minIter 1;
maxIter 1000;
}
}

SIMPLE
{
momentumPredictor yes;
nNonOrthogonalCorrectors 2; // even I tried with 5 as well
pRefCell 0;
pRefValue 0;
convergence 1e-08;

residualControl
{
p 1e-5;
U 1e-5;
nuTilda 1e-5;
}
}

potentialFlow
{
nNonOrthogonalCorrectors 10;
}

relaxationFactors
{
p 0.2;
U 0.7;
k 0.5;
epsilon 0.5;
omega 0.7;
}

Thanks again,
Sivakumar

 doubtsincfd March 15, 2013 16:16

Try running with lower urfs: p=0.2,u=0.4,k=0.2,epsilon=0.2 and see if the results stabilize. If this doesn't work then if possible upload your case people will take a look at it

 sivakumar March 15, 2013 16:21

Hi,
Sure I will try it tomorrow morning, as well I will upload the case if I didnt get success.

Thanks,
Sivakumar

 sivakumar March 16, 2013 05:54

Hi,
I followed your suggestion, the simulation is going on.
Still the epsilon is bounding periodically,

Time = 118

smoothSolver: Solving for Ux, Initial residual = 0.00240776, Final residual = 4.80671e-06, No Iterations 4
smoothSolver: Solving for Uy, Initial residual = 0.00215672, Final residual = 3.97876e-06, No Iterations 4
smoothSolver: Solving for Uz, Initial residual = 0.00114005, Final residual = 2.60887e-06, No Iterations 4
GAMG: Solving for p, Initial residual = 0.0311113, Final residual = 2.6898e-05, No Iterations 6
GAMG: Solving for p, Initial residual = 0.00458921, Final residual = 4.32191e-06, No Iterations 7
GAMG: Solving for p, Initial residual = 0.0011232, Final residual = 1.00024e-06, No Iterations 8
time step continuity errors : sum local = 2.55467e-06, global = -1.96173e-07, cumulative = 0.00316148
smoothSolver: Solving for epsilon, Initial residual = 0.000881991, Final residual = 1.36034e-06, No Iterations 2
smoothSolver: Solving for k, Initial residual = 0.000414547, Final residual = 7.2776e-07, No Iterations 2
ExecutionTime = 4453.44 s ClockTime = 4473 s

Time = 119

smoothSolver: Solving for Ux, Initial residual = 0.00239848, Final residual = 4.78232e-06, No Iterations 4
smoothSolver: Solving for Uy, Initial residual = 0.00214397, Final residual = 3.95226e-06, No Iterations 4
smoothSolver: Solving for Uz, Initial residual = 0.00113472, Final residual = 2.59713e-06, No Iterations 4
GAMG: Solving for p, Initial residual = 0.0309294, Final residual = 2.49886e-05, No Iterations 6
GAMG: Solving for p, Initial residual = 0.00456688, Final residual = 1.74982e-06, No Iterations 8
GAMG: Solving for p, Initial residual = 0.00111512, Final residual = 1.08107e-06, No Iterations 8
time step continuity errors : sum local = 2.77298e-06, global = -1.59081e-07, cumulative = 0.00316132
smoothSolver: Solving for epsilon, Initial residual = 0.00089803, Final residual = 1.3877e-06, No Iterations 2
smoothSolver: Solving for k, Initial residual = 0.000413739, Final residual = 7.26966e-07, No Iterations 2
ExecutionTime = 4474.66 s ClockTime = 4494 s

Time = 120

smoothSolver: Solving for Ux, Initial residual = 0.00238916, Final residual = 4.75864e-06, No Iterations 4
smoothSolver: Solving for Uy, Initial residual = 0.00213133, Final residual = 3.92564e-06, No Iterations 4
smoothSolver: Solving for Uz, Initial residual = 0.00112984, Final residual = 2.58662e-06, No Iterations 4
GAMG: Solving for p, Initial residual = 0.0307649, Final residual = 2.42373e-05, No Iterations 6
GAMG: Solving for p, Initial residual = 0.00454774, Final residual = 2.59207e-06, No Iterations 8
GAMG: Solving for p, Initial residual = 0.00111047, Final residual = 6.3746e-07, No Iterations 9
time step continuity errors : sum local = 1.64113e-06, global = 1.69212e-07, cumulative = 0.00316149
smoothSolver: Solving for epsilon, Initial residual = 0.000914301, Final residual = 1.41542e-06, No Iterations 2
bounding epsilon, min: -0.0724017 max: 1.72002e+06 average: 309.099
smoothSolver: Solving for k, Initial residual = 0.00041297, Final residual = 7.26414e-07, No Iterations 2
ExecutionTime = 4496.58 s ClockTime = 4516 s

forces output:
forces(pressure, viscous)((-5.42683 -12.6105 -46.1923) (-0.114387 -0.810923 0.257543))
moment(pressure, viscous)((2.31694 23.9709 -8.72821) (-0.0377485 -0.118132 -0.491173))

Time = 121

smoothSolver: Solving for Ux, Initial residual = 0.00237927, Final residual = 4.73554e-06, No Iterations 4
smoothSolver: Solving for Uy, Initial residual = 0.00211885, Final residual = 3.90033e-06, No Iterations 4
smoothSolver: Solving for Uz, Initial residual = 0.00112504, Final residual = 2.57666e-06, No Iterations 4
GAMG: Solving for p, Initial residual = 0.0306244, Final residual = 2.39123e-05, No Iterations 6
GAMG: Solving for p, Initial residual = 0.00452987, Final residual = 4.45751e-06, No Iterations 7
GAMG: Solving for p, Initial residual = 0.00110691, Final residual = 9.96202e-07, No Iterations 8
time step continuity errors : sum local = 2.57406e-06, global = -7.09363e-08, cumulative = 0.00316142
smoothSolver: Solving for epsilon, Initial residual = 0.000931199, Final residual = 1.44355e-06, No Iterations 2
smoothSolver: Solving for k, Initial residual = 0.000412199, Final residual = 7.2598e-07, No Iterations 2
ExecutionTime = 4518.05 s ClockTime = 4538 s

Time = 122

smoothSolver: Solving for Ux, Initial residual = 0.00236962, Final residual = 4.7119e-06, No Iterations 4
smoothSolver: Solving for Uy, Initial residual = 0.00210644, Final residual = 3.87452e-06, No Iterations 4
smoothSolver: Solving for Uz, Initial residual = 0.00112029, Final residual = 2.56647e-06, No Iterations 4
GAMG: Solving for p, Initial residual = 0.0304902, Final residual = 2.48185e-05, No Iterations 6
GAMG: Solving for p, Initial residual = 0.00451779, Final residual = 4.2044e-06, No Iterations 7
GAMG: Solving for p, Initial residual = 0.00110201, Final residual = 1.09358e-06, No Iterations 8
time step continuity errors : sum local = 2.83434e-06, global = -3.41901e-07, cumulative = 0.00316107
smoothSolver: Solving for epsilon, Initial residual = 0.000948287, Final residual = 1.47169e-06, No Iterations 2
smoothSolver: Solving for k, Initial residual = 0.000411494, Final residual = 7.25535e-07, No Iterations 2
ExecutionTime = 4538.71 s ClockTime = 4558 s

Time = 123

smoothSolver: Solving for Ux, Initial residual = 0.00236437, Final residual = 4.68802e-06, No Iterations 4
smoothSolver: Solving for Uy, Initial residual = 0.00209582, Final residual = 3.84905e-06, No Iterations 4
smoothSolver: Solving for Uz, Initial residual = 0.00111566, Final residual = 2.55566e-06, No Iterations 4
GAMG: Solving for p, Initial residual = 0.0303963, Final residual = 2.92078e-05, No Iterations 6
GAMG: Solving for p, Initial residual = 0.00452022, Final residual = 2.77572e-06, No Iterations 7
GAMG: Solving for p, Initial residual = 0.00109964, Final residual = 5.38716e-07, No Iterations 9
time step continuity errors : sum local = 1.40016e-06, global = -1.38135e-07, cumulative = 0.00316094
smoothSolver: Solving for epsilon, Initial residual = 0.000965462, Final residual = 1.49959e-06, No Iterations 2
bounding epsilon, min: -20.9065 max: 1.95269e+06 average: 309.411
smoothSolver: Solving for k, Initial residual = 0.000410838, Final residual = 7.25081e-07, No Iterations 2
ExecutionTime = 4559.97 s ClockTime = 4580 s

Time = 124

smoothSolver: Solving for Ux, Initial residual = 0.00235251, Final residual = 4.66555e-06, No Iterations 4
smoothSolver: Solving for Uy, Initial residual = 0.00208287, Final residual = 3.82509e-06, No Iterations 4
smoothSolver: Solving for Uz, Initial residual = 0.00111042, Final residual = 2.54389e-06, No Iterations 4
GAMG: Solving for p, Initial residual = 0.0302671, Final residual = 1.14071e-05, No Iterations 8
GAMG: Solving for p, Initial residual = 0.00451747, Final residual = 2.7175e-06, No Iterations 8
GAMG: Solving for p, Initial residual = 0.00109837, Final residual = 8.3546e-07, No Iterations 8
time step continuity errors : sum local = 2.17806e-06, global = -2.73555e-07, cumulative = 0.00316066
smoothSolver: Solving for epsilon, Initial residual = 0.000982573, Final residual = 1.52709e-06, No Iterations 2
bounding epsilon, min: -0.056677 max: 2.03122e+06 average: 309.634
smoothSolver: Solving for k, Initial residual = 0.000410131, Final residual = 7.24574e-07, No Iterations 2
ExecutionTime = 4582.15 s ClockTime = 4602 s

Time = 125

smoothSolver: Solving for Ux, Initial residual = 0.00234385, Final residual = 4.64191e-06, No Iterations 4
smoothSolver: Solving for Uy, Initial residual = 0.00207182, Final residual = 3.80037e-06, No Iterations 4
smoothSolver: Solving for Uz, Initial residual = 0.00110526, Final residual = 2.53165e-06, No Iterations 4
GAMG: Solving for p, Initial residual = 0.0301641, Final residual = 1.2017e-05, No Iterations 8
GAMG: Solving for p, Initial residual = 0.00451392, Final residual = 2.52417e-06, No Iterations 8
GAMG: Solving for p, Initial residual = 0.00110063, Final residual = 1.01985e-06, No Iterations 8
time step continuity errors : sum local = 2.66683e-06, global = 4.25343e-07, cumulative = 0.00316109
smoothSolver: Solving for epsilon, Initial residual = 0.000999888, Final residual = 1.55423e-06, No Iterations 2
bounding epsilon, min: -12.2889 max: 2.11e+06 average: 309.92
smoothSolver: Solving for k, Initial residual = 0.000409478, Final residual = 7.2409e-07, No Iterations 2
ExecutionTime = 4604.31 s ClockTime = 4624 s

Time = 126

smoothSolver: Solving for Ux, Initial residual = 0.00237254, Final residual = 4.64063e-06, No Iterations 4
smoothSolver: Solving for Uy, Initial residual = 0.00209442, Final residual = 3.7683e-06, No Iterations 4
smoothSolver: Solving for Uz, Initial residual = 0.00110732, Final residual = 2.52517e-06, No Iterations 4
GAMG: Solving for p, Initial residual = 0.0300672, Final residual = 1.18966e-05, No Iterations 8
GAMG: Solving for p, Initial residual = 0.00454405, Final residual = 3.01768e-06, No Iterations 8
GAMG: Solving for p, Initial residual = 0.00113615, Final residual = 1.0217e-06, No Iterations 8
time step continuity errors : sum local = 2.68079e-06, global = -4.77359e-07, cumulative = 0.00316061
smoothSolver: Solving for epsilon, Initial residual = 0.00101735, Final residual = 1.58086e-06, No Iterations 2
bounding epsilon, min: -0.304008 max: 2.18899e+06 average: 310.272
smoothSolver: Solving for k, Initial residual = 0.000409422, Final residual = 7.24154e-07, No Iterations 2
ExecutionTime = 4626.69 s ClockTime = 4647 s

Time = 127

smoothSolver: Solving for Ux, Initial residual = 0.00232783, Final residual = 4.59634e-06, No Iterations 4
smoothSolver: Solving for Uy, Initial residual = 0.00205179, Final residual = 3.75462e-06, No Iterations 4
smoothSolver: Solving for Uz, Initial residual = 0.00109526, Final residual = 2.50748e-06, No Iterations 4
GAMG: Solving for p, Initial residual = 0.0301061, Final residual = 1.12072e-05, No Iterations 8
GAMG: Solving for p, Initial residual = 0.00453209, Final residual = 2.90322e-06, No Iterations 8
GAMG: Solving for p, Initial residual = 0.00112219, Final residual = 6.92667e-07, No Iterations 8
time step continuity errors : sum local = 1.82403e-06, global = -2.7025e-07, cumulative = 0.00316034
smoothSolver: Solving for epsilon, Initial residual = 0.00103626, Final residual = 1.60873e-06, No Iterations 2
smoothSolver: Solving for k, Initial residual = 0.000408179, Final residual = 7.23165e-07, No Iterations 2
ExecutionTime = 4648.99 s ClockTime = 4669 s

Time = 128

smoothSolver: Solving for Ux, Initial residual = 0.00233405, Final residual = 4.57661e-06, No Iterations 4
smoothSolver: Solving for Uy, Initial residual = 0.0020616, Final residual = 3.73717e-06, No Iterations 4
smoothSolver: Solving for Uz, Initial residual = 0.00109168, Final residual = 2.49664e-06, No Iterations 4
GAMG: Solving for p, Initial residual = 0.0302755, Final residual = 2.97982e-05, No Iterations 6
GAMG: Solving for p, Initial residual = 0.00459348, Final residual = 3.73943e-06, No Iterations 7
GAMG: Solving for p, Initial residual = 0.00114733, Final residual = 8.23085e-07, No Iterations 8
time step continuity errors : sum local = 2.17593e-06, global = 3.18905e-07, cumulative = 0.00316066
smoothSolver: Solving for epsilon, Initial residual = 0.00105797, Final residual = 1.64059e-06, No Iterations 2
bounding epsilon, min: -569.998 max: 2.3476e+06 average: 311.181
smoothSolver: Solving for k, Initial residual = 0.000407702, Final residual = 7.22822e-07, No Iterations 2
ExecutionTime = 4669.93 s ClockTime = 4690 s

Time = 129

smoothSolver: Solving for Ux, Initial residual = 0.00231227, Final residual = 4.55455e-06, No Iterations 4
smoothSolver: Solving for Uy, Initial residual = 0.00203203, Final residual = 3.71174e-06, No Iterations 4
smoothSolver: Solving for Uz, Initial residual = 0.00108599, Final residual = 2.48557e-06, No Iterations 4
GAMG: Solving for p, Initial residual = 0.0301049, Final residual = 2.50101e-05, No Iterations 6
GAMG: Solving for p, Initial residual = 0.00452806, Final residual = 3.94536e-06, No Iterations 7
GAMG: Solving for p, Initial residual = 0.00113453, Final residual = 8.28034e-07, No Iterations 8
time step continuity errors : sum local = 2.19744e-06, global = 2.68305e-07, cumulative = 0.00316093
smoothSolver: Solving for epsilon, Initial residual = 0.00107901, Final residual = 1.67225e-06, No Iterations 2
smoothSolver: Solving for k, Initial residual = 0.000406932, Final residual = 7.22438e-07, No Iterations 2
ExecutionTime = 4690.56 s ClockTime = 4711 s

Time = 130

smoothSolver: Solving for Ux, Initial residual = 0.00230389, Final residual = 4.53324e-06, No Iterations 4
smoothSolver: Solving for Uy, Initial residual = 0.00202131, Final residual = 3.69045e-06, No Iterations 4
smoothSolver: Solving for Uz, Initial residual = 0.00108174, Final residual = 2.47573e-06, No Iterations 4
GAMG: Solving for p, Initial residual = 0.0300052, Final residual = 2.32653e-05, No Iterations 6
GAMG: Solving for p, Initial residual = 0.00451055, Final residual = 3.54447e-06, No Iterations 7
GAMG: Solving for p, Initial residual = 0.00113564, Final residual = 7.23024e-07, No Iterations 8
time step continuity errors : sum local = 1.92608e-06, global = -2.34593e-07, cumulative = 0.00316069
smoothSolver: Solving for epsilon, Initial residual = 0.00110286, Final residual = 1.70802e-06, No Iterations 2
smoothSolver: Solving for k, Initial residual = 0.000406402, Final residual = 7.22228e-07, No Iterations 2
ExecutionTime = 4711.44 s ClockTime = 4732 s

forces output:
forces(pressure, viscous)((-4.78114 -12.7469 -46.3158) (-0.113974 -0.809523 0.255371))
moment(pressure, viscous)((1.98857 24.1224 -8.72209) (-0.037699 -0.117629 -0.491441))

Time = 131

smoothSolver: Solving for Ux, Initial residual = 0.00229575, Final residual = 4.51222e-06, No Iterations 4
smoothSolver: Solving for Uy, Initial residual = 0.00201099, Final residual = 3.66935e-06, No Iterations 4
smoothSolver: Solving for Uz, Initial residual = 0.00107776, Final residual = 2.46639e-06, No Iterations 4
GAMG: Solving for p, Initial residual = 0.0299727, Final residual = 2.28834e-05, No Iterations 6
GAMG: Solving for p, Initial residual = 0.00450915, Final residual = 1.61566e-06, No Iterations 8
GAMG: Solving for p, Initial residual = 0.00113737, Final residual = 6.41323e-07, No Iterations 8
time step continuity errors : sum local = 1.71533e-06, global = 2.13773e-07, cumulative = 0.00316091
smoothSolver: Solving for epsilon, Initial residual = 0.00112956, Final residual = 1.74827e-06, No Iterations 2
smoothSolver: Solving for k, Initial residual = 0.000405945, Final residual = 7.22167e-07, No Iterations 2
ExecutionTime = 4733.32 s ClockTime = 4754 s

Time = 132

smoothSolver: Solving for Ux, Initial residual = 0.00228789, Final residual = 4.49207e-06, No Iterations 4
smoothSolver: Solving for Uy, Initial residual = 0.00200059, Final residual = 3.64838e-06, No Iterations 4
smoothSolver: Solving for Uz, Initial residual = 0.00107406, Final residual = 2.45738e-06, No Iterations 4
GAMG: Solving for p, Initial residual = 0.0299324, Final residual = 2.31512e-05, No Iterations 6
GAMG: Solving for p, Initial residual = 0.00451329, Final residual = 1.8372e-06, No Iterations 8
GAMG: Solving for p, Initial residual = 0.00114086, Final residual = 4.80326e-07, No Iterations 8
time step continuity errors : sum local = 1.28977e-06, global = 3.32669e-07, cumulative = 0.00316124
smoothSolver: Solving for epsilon, Initial residual = 0.00115991, Final residual = 1.79542e-06, No Iterations 2
bounding epsilon, min: -3.43825 max: 2.95652e+06 average: 313.953
smoothSolver: Solving for k, Initial residual = 0.00040565, Final residual = 7.22344e-07, No Iterations 2
ExecutionTime = 4754.86 s ClockTime = 4776 s

Time = 133

smoothSolver: Solving for Ux, Initial residual = 0.00227798, Final residual = 4.47128e-06, No Iterations 4
smoothSolver: Solving for Uy, Initial residual = 0.00199017, Final residual = 3.62777e-06, No Iterations 4
smoothSolver: Solving for Uz, Initial residual = 0.00107029, Final residual = 2.44863e-06, No Iterations 4
GAMG: Solving for p, Initial residual = 0.0298756, Final residual = 2.37801e-05, No Iterations 6
GAMG: Solving for p, Initial residual = 0.00450553, Final residual = 2.04085e-06, No Iterations 8
GAMG: Solving for p, Initial residual = 0.00113932, Final residual = 5.35346e-07, No Iterations 8
time step continuity errors : sum local = 1.44307e-06, global = 3.99711e-07, cumulative = 0.00316164
smoothSolver: Solving for epsilon, Initial residual = 0.00119524, Final residual = 1.85147e-06, No Iterations 2
smoothSolver: Solving for k, Initial residual = 0.000405338, Final residual = 7.22478e-07, No Iterations 2
ExecutionTime = 4776.02 s ClockTime = 4797 s

the simulation is going on with out struck.
I am not sure about the quality of the results.

Please have a look of the above output and advise me is it fine or do I need to do any further refinement.

Thanks,
Sivakumar

 sivakumar March 16, 2013 06:59

Hi everyone,
I tried my level best and I followed Champhekar suggestionsas well.

I am not getting success, so I have uploaded the case in sendspace.

The like is : http://www.sendspace.com/file/3fy5fm

Thanks,
Sivakumar

 sivakumar March 17, 2013 06:37

Hi Everyone,
I realized the problem.
The problem is non- orthogonality faces,

I got some information regarding this,

0 to 50 full corrected scheme is applicable,
50 to 70 limited correction is required,
70 to 80 stability possible, accuracy compromised,
above 80 stability very difficult to attain

In my case, my mesh has 99 non orthogonal cells with the angle of

Mesh non-orthogonality Max: 82.8897 average: 5.76063

We can see the difference between running mesh and problematic mesh from the previous mesh.

I feel this is my problem.

Thanks,
Sivakumar

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