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barath.ezhilan July 13, 2009 10:52

Problems with simulating TurbFOAM
 
Hi All,

I am trying to simulate swirling flow in the draft tube of the turbine using KOmegaSST turbulence model with TurbFOAM and I am having a problem with it. The simulations stops after a few time steps. I have a delta T 1e-5 and I have also tried increasing the number of correctors and orthogonal correctors etc. The Mesh is fine, checkMesh says the Mesh is OK. I have also checked the boundary files

The log file:::

Time = 9.55556e-05

Courant Number mean: 0.00131032 max: 7.52485 velocity magnitude: 260.087
PBiCG: Solving for Ux, Initial residual = 0.104884, Final residual = 0.00497614, No Iterations 2
PBiCG: Solving for Uy, Initial residual = 0.110647, Final residual = 0.00209042, No Iterations 2
PBiCG: Solving for Uz, Initial residual = 0.0109506, Final residual = 0.000402031, No Iterations 2
PCG: Solving for p, Initial residual = 0.905193, Final residual = 0.00849971, No Iterations 19
time step continuity errors : sum local = 3.95906e-06, global = 2.96857e-08, cumulative = 2.60243e-07
PCG: Solving for p, Initial residual = 0.903698, Final residual = 0.0077981, No Iterations 21
time step continuity errors : sum local = 5.59011e-06, global = 2.96251e-08, cumulative = 2.89868e-07
PBiCG: Solving for omega, Initial residual = 0.0521617, Final residual = 0.00171759, No Iterations 2
bounding omega, min: -3.10703e+06 max: 1.37457e+07 average: 6537.53
PBiCG: Solving for k, Initial residual = 0.0759318, Final residual = 0.00116278, No Iterations 2
bounding k, min: -0.228331 max: 4.29478 average: 0.0111114
ExecutionTime = 293.4 s ClockTime = 295 s

Time = 0.000105556

Courant Number mean: 0.00177524 max: 16.8808 velocity magnitude: 532.235
PBiCG: Solving for Ux, Initial residual = 0.207847, Final residual = 0.0171767, No Iterations 2
PBiCG: Solving for Uy, Initial residual = 0.230103, Final residual = 0.0131825, No Iterations 2
PBiCG: Solving for Uz, Initial residual = 0.0368306, Final residual = 0.00168079, No Iterations 2
PCG: Solving for p, Initial residual = 0.905287, Final residual = 0.00834842, No Iterations 24
time step continuity errors : sum local = 7.86545e-06, global = 3.42434e-08, cumulative = 3.24111e-07
PCG: Solving for p, Initial residual = 0.909423, Final residual = 0.00750422, No Iterations 24
time step continuity errors : sum local = 1.0548e-05, global = 3.40615e-08, cumulative = 3.58173e-07
PBiCG: Solving for omega, Initial residual = 0.0586053, Final residual = 0.00481685, No Iterations 2
bounding omega, min: -1.3806e+07 max: 2.58179e+07 average: 13489.3
PBiCG: Solving for k, Initial residual = 0.0920886, Final residual = 0.00343743, No Iterations 2
bounding k, min: -1.52212 max: 6.6377 average: 0.0125395
ExecutionTime = 307.73 s ClockTime = 309 s

Time = 0.000115556

Courant Number mean: 0.00234709 max: 21.606 velocity magnitude: 748.857
PBiCG: Solving for Ux, Initial residual = 0.344634, Final residual = 0.0099675, No Iterations 3
PBiCG: Solving for Uy, Initial residual = 0.329588, Final residual = 0.0101443, No Iterations 3
PBiCG: Solving for Uz, Initial residual = 0.0829345, Final residual = 0.00185229, No Iterations 3
PCG: Solving for p, Initial residual = 0.894228, Final residual = 0.0069595, No Iterations 77
time step continuity errors : sum local = 1.32459e-05, global = 3.74457e-08, cumulative = 3.95619e-07
PCG: Solving for p, Initial residual = 0.941143, Final residual = 0.00818695, No Iterations 100
time step continuity errors : sum local = 4.97055e-05, global = 3.5411e-08, cumulative = 4.3103e-07
PBiCG: Solving for omega, Initial residual = 1, Final residual = 0.0738547, No Iterations 76
bounding omega, min: -1.39421e+19 max: 2.83497e+19 average: 8.33634e+14
PBiCG: Solving for k, Initial residual = 0.929398, Final residual = 2.79674e-11, No Iterations 1
bounding k, min: -1.05884 max: 9.29845 average: 0.00995458
ExecutionTime = 347.03 s ClockTime = 349 s

Time = 0.000125556

Courant Number mean: 0.0842083 max: 107356 velocity magnitude: 6.87564e+06
PBiCG: Solving for Ux, Initial residual = 0.999926, Final residual = 5.05889, No Iterations 1000
PBiCG: Solving for Uy, Initial residual = 0.999817, Final residual = 15.8907, No Iterations 1000
PBiCG: Solving for Uz, Initial residual = 0.999843, Final residual = 6.45841, No Iterations 1000
PCG: Solving for p, Initial residual = 0.999999, Final residual = 0.415433, No Iterations 1000
time step continuity errors : sum local = 6410.55, global = 3.66894e-08, cumulative = 4.67719e-07
PCG: Solving for p, Initial residual = 0.996811, Final residual = 0.317644, No Iterations 1000
time step continuity errors : sum local = 1.70248e+06, global = 3.65351e-08, cumulative = 5.04254e-07
~

The files in the system folder are given below

ControlDict::::

application turbFoam;

startFrom latestTime;

startTime 0;

stopAt endTime;

endTime 0.3;

deltaT 0.00005;

writeControl timeStep;

writeInterval 50;

purgeWrite 0;

writeFormat ascii;

writePrecision 6;

writeCompression compressed;

timeFormat general;

timePrecision 6;

runTimeModifiable no;

// libs ("libaddedIncompressibleRASModels.so");
libs ("libOpenFoamTurbo.so" );

Schemes File::

ddtSchemes
{
default Euler;
}

gradSchemes
{
default Gauss linear;
grad(p) Gauss linear;
grad(U) Gauss linear;
}

divSchemes
{
default none;
div(phi,U) Gauss limitedLinearV 1;
div(phi,k) Gauss limitedLinear 1;
div(phi,epsilon) Gauss limitedLinear 1;
div(phi,omega) Gauss limitedLinear 1;
div(phi,R) Gauss limitedLinear 1;
div(R) Gauss linear;
div(phi,nuTilda) Gauss limitedLinear 1;
div((nuEff*dev(grad(U).T()))) Gauss linear;
}

laplacianSchemes
{
default none;
laplacian(nuEff,U) Gauss linear corrected;
laplacian((1|A(U)),p) Gauss linear corrected;
laplacian(DkEff,k) Gauss linear corrected;
laplacian(DepsilonEff,epsilon) Gauss linear corrected;
laplacian(DomegaEff,omega) Gauss linear corrected;
laplacian(DREff,R) Gauss linear corrected;
laplacian(DnuTildaEff,nuTilda) Gauss linear corrected;
}

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

snGradSchemes
{
default corrected;
}

fluxRequired
{
default no;
p;
}

Solution File::

solvers
{
p PCG
{
preconditioner DIC;
tolerance 1e-06;
relTol 0.01;
};
U PBiCG
{
preconditioner DILU;
tolerance 1e-05;
relTol 0.1;
};
k PBiCG
{
preconditioner DILU;
tolerance 1e-05;
relTol 0.1;
};
epsilon PBiCG
{
preconditioner DILU;
tolerance 1e-05;
relTol 0.1;
};
omega PBiCG
{
preconditioner DILU;
tolerance 1e-05;
relTol 0.1;
};
R PBiCG
{
preconditioner DILU;
tolerance 1e-05;
relTol 0.1;
};
nuTilda PBiCG
{
preconditioner DILU;
tolerance 1e-05;
relTol 0.1;
};
PISO
{
nCorrectors 4;
nNonOrthogonalCorrectors 2;
pRefCell 0;
pRefValue 0;
}



Please do help me this regard as to what I can do to solve this problem???

mixer July 14, 2009 03:13

Hi Barath

The epsilon and omega are getting out of bounds,

Use the 'limited settings' for laplacian of omega and epsilon, say,

laplacian(DepsilonEff,epsilon) Gauss linear limited 0.3;
laplacian(DomegaEff,omega) Gauss linear limited 0.3;

also, possibly see if BC value's of epsilon and omega can be made more realistic.

santos July 14, 2009 05:34

Hello,

Try to decrease your deltaT, your max Courant number is very high (it should be <1). Also, run your case first with upwind on div convection terms, and change your relTol to 0 for all variables in fvSolution.

Regards,
Jose Santos

barath.ezhilan July 14, 2009 07:51

Limited settings not working
 
Hi Menter,

I have tried applying the limited settings, but it still doesnt seem to work. Please tell what else can be done.


Quote:

Originally Posted by mixer (Post 222561)
Hi Barath

The epsilon and omega are getting out of bounds,

Use the 'limited settings' for laplacian of omega and epsilon, say,

laplacian(DepsilonEff,epsilon) Gauss linear limited 0.3;
laplacian(DomegaEff,omega) Gauss linear limited 0.3;

also, possibly see if BC value's of epsilon and omega can be made more realistic.


barath.ezhilan July 14, 2009 07:55

Hi!!!
 
Hi Jose Santos,

I have chosen a time step 5E-5 and the initial courant number is quite low only (of the order of 1E-3). My FvSolution doesnot have any relTol, (I am using the settings provided in the cavity folder of TURBfoam tutorials) Will that be in any way the reason for the problem?

Quote:

Originally Posted by santos (Post 222577)
Hello,

Try to decrease your deltaT, your max Courant number is very high (it should be <1). Also, run your case first with upwind on div convection terms, and change your relTol to 0 for all variables in fvSolution.

Regards,
Jose Santos


santos July 15, 2009 06:05

Does it still diverge with those settings? The settings you showed on your first post were different.

Jose Santos

barath.ezhilan July 15, 2009 06:35

Hi santos,

Which settings are you referring to ??

My first post also shows the deltaT settings to be 5E-5 (deltaT 0.00005), and the courant number of the first few time steps was also 1E-3 .


Quote:

Originally Posted by santos (Post 222719)
Does it still diverge with those settings? The settings you showed on your first post were different.

Jose Santos


santos July 15, 2009 06:45

Your mean Co was 1e-3, but your max Co = 7. Moreover, the fvSolution you showed has relTol 0.01 and 0.1 for most variables.

Jose Santos

barath.ezhilan July 15, 2009 06:51

Hi Santos,

Thanks, I will change the relTol, and try simulating

Quote:

Originally Posted by santos (Post 222732)
Your mean Co was 1e-3, but your max Co = 7. Moreover, the fvSolution you showed has relTol 0.01 and 0.1 for most variables.

Jose Santos


barath.ezhilan July 15, 2009 19:29

Hi Santos,

I changed the relTol settings to 0 and simulated. The problem still exists (as you see below, in the log file)!!!! any suggestions??


Time = 5e-05

Courant Number mean: 0.000358108 max: 0.243795 velocity magnitude: 3.22114
PBiCG: Solving for Ux, Initial residual = 1, Final residual = 1.81664e-06, No Iterations 2
PBiCG: Solving for Uy, Initial residual = 1, Final residual = 1.82548e-06, No Iterations 2
PBiCG: Solving for Uz, Initial residual = 1, Final residual = 5.26316e-06, No Iterations 3
PCG: Solving for p, Initial residual = 1, Final residual = 9.93795e-07, No Iterations 439
PCG: Solving for p, Initial residual = 0.0190973, Final residual = 9.01639e-07, No Iterations 359
PCG: Solving for p, Initial residual = 0.00380892, Final residual = 9.84682e-07, No Iterations 353
time step continuity errors : sum local = 2.62486e-08, global = -8.42758e-11, cumulative = -8.42758e-11
PCG: Solving for p, Initial residual = 0.00477481, Final residual = 9.89681e-07, No Iterations 360
PCG: Solving for p, Initial residual = 0.00557558, Final residual = 9.75184e-07, No Iterations 353
PCG: Solving for p, Initial residual = 0.00209781, Final residual = 9.6199e-07, No Iterations 346
time step continuity errors : sum local = 2.32097e-08, global = 6.46285e-12, cumulative = -7.78129e-11
PCG: Solving for p, Initial residual = 0.00252374, Final residual = 9.31564e-07, No Iterations 346
PCG: Solving for p, Initial residual = 0.00159287, Final residual = 9.71556e-07, No Iterations 342
PCG: Solving for p, Initial residual = 0.00109841, Final residual = 9.93416e-07, No Iterations 338
time step continuity errors : sum local = 2.37934e-08, global = 1.25654e-10, cumulative = 4.78414e-11
PCG: Solving for p, Initial residual = 0.00147234, Final residual = 9.52147e-07, No Iterations 341
PCG: Solving for p, Initial residual = 0.00126403, Final residual = 8.98022e-07, No Iterations 338
PCG: Solving for p, Initial residual = 0.00100686, Final residual = 9.89063e-07, No Iterations 333
time step continuity errors : sum local = 2.36568e-08, global = 1.71118e-10, cumulative = 2.1896e-10
PBiCG: Solving for omega, Initial residual = 0.0079402, Final residual = 4.81707e-06, No Iterations 2
bounding omega, min: -39.8115 max: 12127.3 average: 105.149
PBiCG: Solving for k, Initial residual = 1, Final residual = 2.89074e-06, No Iterations 5
ExecutionTime = 606.88 s ClockTime = 614 s

Time = 0.0001

Courant Number mean: 0.00502222 max: 0.918015 velocity magnitude: 5.37594
PBiCG: Solving for Ux, Initial residual = 0.335416, Final residual = 2.71144e-07, No Iterations 3
PBiCG: Solving for Uy, Initial residual = 0.335463, Final residual = 2.6876e-07, No Iterations 3
PBiCG: Solving for Uz, Initial residual = 0.863441, Final residual = 5.86173e-06, No Iterations 2
PCG: Solving for p, Initial residual = 0.00982878, Final residual = 8.78105e-07, No Iterations 372
PCG: Solving for p, Initial residual = 0.20334, Final residual = 9.20665e-07, No Iterations 384
PCG: Solving for p, Initial residual = 0.0678486, Final residual = 9.55188e-07, No Iterations 380
time step continuity errors : sum local = 2.04639e-09, global = 3.35027e-13, cumulative = 2.19295e-10
PCG: Solving for p, Initial residual = 0.0850855, Final residual = 9.56664e-07, No Iterations 379
PCG: Solving for p, Initial residual = 0.38827, Final residual = 9.73532e-07, No Iterations 390
PCG: Solving for p, Initial residual = 0.316163, Final residual = 9.23616e-07, No Iterations 386
time step continuity errors : sum local = 4.21096e-10, global = 2.25754e-13, cumulative = 2.1952e-10
PCG: Solving for p, Initial residual = 0.424259, Final residual = 9.47635e-07, No Iterations 386
PCG: Solving for p, Initial residual = 0.474849, Final residual = 9.68887e-07, No Iterations 382
PCG: Solving for p, Initial residual = 0.512805, Final residual = 9.25307e-07, No Iterations 381
time step continuity errors : sum local = 4.93901e-10, global = -4.74778e-13, cumulative = 2.19046e-10
PCG: Solving for p, Initial residual = 0.618267, Final residual = 9.08134e-07, No Iterations 380
PCG: Solving for p, Initial residual = 0.645274, Final residual = 9.47856e-07, No Iterations 379
PCG: Solving for p, Initial residual = 0.684602, Final residual = 9.86349e-07, No Iterations 378
time step continuity errors : sum local = 8.37812e-10, global = -4.68039e-13, cumulative = 2.18578e-10
PBiCG: Solving for omega, Initial residual = 0.415049, Final residual = 8.50722e-06, No Iterations 8
bounding omega, min: -2.38491e+06 max: 3.60791e+07 average: 6236.52
PBiCG: Solving for k, Initial residual = 0.65272, Final residual = 1.54235e-06, No Iterations 4
bounding k, min: -0.00274926 max: 0.127536 average: 0.0102244
ExecutionTime = 1240.58 s ClockTime = 1253 s

Time = 0.00015

Courant Number mean: 0.00524007 max: 5.76168 velocity magnitude: 44.0043
PBiCG: Solving for Ux, Initial residual = 0.0672304, Final residual = 9.43873e-06, No Iterations 6
PBiCG: Solving for Uy, Initial residual = 0.0670888, Final residual = 1.98847e-06, No Iterations 7
PBiCG: Solving for Uz, Initial residual = 0.00481512, Final residual = 7.2339e-06, No Iterations 4
PCG: Solving for p, Initial residual = 0.824352, Final residual = 9.17862e-07, No Iterations 389
PCG: Solving for p, Initial residual = 0.698699, Final residual = 9.93409e-07, No Iterations 384
PCG: Solving for p, Initial residual = 0.727276, Final residual = 9.97471e-07, No Iterations 387
time step continuity errors : sum local = 1.60855e-09, global = -1.68868e-12, cumulative = 2.16889e-10
PCG: Solving for p, Initial residual = 0.876338, Final residual = 9.49251e-07, No Iterations 389
PCG: Solving for p, Initial residual = 0.84503, Final residual = 9.53187e-07, No Iterations 391
PCG: Solving for p, Initial residual = 0.879094, Final residual = 8.97079e-07, No Iterations 392
time step continuity errors : sum local = 2.47347e-09, global = -1.6306e-12, cumulative = 2.15258e-10
PCG: Solving for p, Initial residual = 0.95115, Final residual = 9.62471e-07, No Iterations 391
PCG: Solving for p, Initial residual = 0.87138, Final residual = 9.16364e-07, No Iterations 392
PCG: Solving for p, Initial residual = 0.887653, Final residual = 9.34473e-07, No Iterations 392
time step continuity errors : sum local = 4.73105e-09, global = 2.88022e-12, cumulative = 2.18139e-10
PCG: Solving for p, Initial residual = 0.962629, Final residual = 9.87552e-07, No Iterations 390
PCG: Solving for p, Initial residual = 0.883919, Final residual = 9.9326e-07, No Iterations 392
PCG: Solving for p, Initial residual = 0.905319, Final residual = 9.56255e-07, No Iterations 393
time step continuity errors : sum local = 8.67916e-09, global = -2.17652e-12, cumulative = 2.15962e-10
PBiCG: Solving for omega, Initial residual = 0.557895, Final residual = 8.90059e-06, No Iterations 30
bounding omega, min: -1.9486e+07 max: 5.4919e+08 average: 159539
PBiCG: Solving for k, Initial residual = 0.607767, Final residual = 6.63983e-06, No Iterations 5
bounding k, min: -0.254928 max: 1.0788 average: 0.0112812
ExecutionTime = 1902.14 s ClockTime = 1924 s

Time = 0.0002

Courant Number mean: 0.0120517 max: 243.737 velocity magnitude: 1747.7
PBiCG: Solving for Ux, Initial residual = 0.760947, Final residual = 8.84033e-06, No Iterations 39
PBiCG: Solving for Uy, Initial residual = 0.774137, Final residual = 3.97576e-06, No Iterations 38
PBiCG: Solving for Uz, Initial residual = 0.506527, Final residual = 9.29213e-06, No Iterations 33
PCG: Solving for p, Initial residual = 0.78, Final residual = 8.87942e-07, No Iterations 615
PCG: Solving for p, Initial residual = 0.547448, Final residual = 7.41311e-07, No Iterations 601
PCG: Solving for p, Initial residual = 0.455372, Final residual = 6.3829e-07, No Iterations 620
time step continuity errors : sum local = 7.9754e-09, global = 6.46518e-11, cumulative = 2.80614e-10
PCG: Solving for p, Initial residual = 0.832319, Final residual = 8.24641e-07, No Iterations 601
PCG: Solving for p, Initial residual = 0.487072, Final residual = 7.58123e-07, No Iterations 619
PCG: Solving for p, Initial residual = 0.354087, Final residual = 8.01443e-07, No Iterations 604
time step continuity errors : sum local = 4.46259e-08, global = -6.1831e-11, cumulative = 2.18783e-10
PCG: Solving for p, Initial residual = 0.978763, Final residual = 6.43371e-07, No Iterations 616
PCG: Solving for p, Initial residual = 0.487253, Final residual = 9.60152e-07, No Iterations 602
PCG: Solving for p, Initial residual = 0.33208, Final residual = 3.72602e-07, No Iterations 596
time step continuity errors : sum local = 6.06844e-07, global = 4.93755e-09, cumulative = 5.15634e-09
PCG: Solving for p, Initial residual = 0.983923, Final residual = 9.73328e-07, No Iterations 606
PCG: Solving for p, Initial residual = 0.48976, Final residual = 7.46673e-07, No Iterations 591
PCG: Solving for p, Initial residual = 0.291791, Final residual = 6.55602e-07, No Iterations 587
time step continuity errors : sum local = 4.414e-05, global = 7.197e-07, cumulative = 7.24857e-07
PBiCG: Solving for omega, Initial residual = 0.999997, Final residual = 3.08064e+07, No Iterations 1000
bounding omega, min: -7.25689e+24 max: 5.46641e+24 average: -1.03469e+20
PBiCG: Solving for k, Initial residual = 0.81231, Final residual = 3.54624e-11, No Iterations 1
bounding k, min: -53823.1 max: 106.182 average: -6.48604
ExecutionTime = 3236.79 s ClockTime = 3276 s

Time = 0.00025

Courant Number mean: 25.0656 max: 2.5079e+07 velocity magnitude: 2.38043e+08
PBiCG: Solving for Ux, Initial residual = 0.999999, Final residual = 0.999999, No Iterations 1000
PBiCG: Solving for Uy, Initial residual = 0.999999, Final residual = 0.999999, No Iterations 1000
PBiCG: Solving for Uz, Initial residual = 0.999999, Final residual = 1.16832, No Iterations 1000
PCG: Solving for p, Initial residual = 0.999999, Final residual = 0.119066, No Iterations 1000
PCG: Solving for p, Initial residual = 0.0904133, Final residual = 3.89395, No Iterations 1000
PCG: Solving for p, Initial residual = 0.796989, Final residual = 2.27701, No Iterations 1000
time step continuity errors : sum local = 3.30829e+08, global = 1.40983e-06, cumulative = 2.13468e-06
PCG: Solving for p, Initial residual = 0.999459, Final residual = 4.68481, No Iterations 1000
PCG: Solving for p, Initial residual = 0.870245, Final residual = 1.35971, No Iterations 1000
PCG: Solving for p, Initial residual = 0.848326, Final residual = 6.07145, No Iterations 1000
time step continuity errors : sum local = 6.48284e+13, global = 0.0104131, cumulative = 0.0104153
PCG: Solving for p, Initial residual = 0.999416, Final residual = 1.60614, No Iterations 1000
PCG: Solving for p, Initial residual = 0.831019, Final residual = 1.93253, No Iterations 1000
PCG: Solving for p, Initial residual = 0.833148, Final residual = 2.24912, No Iterations 1000
time step continuity errors : sum local = 2.18907e+18, global = -93.1258, cumulative = -93.1154
PCG: Solving for p, Initial residual = 0.999613, Final residual = 6.6956, No Iterations 1000
PCG: Solving for p, Initial residual = 0.880524, Final residual = 37.3175, No Iterations 1000
PCG: Solving for p, Initial residual = 0.880441, Final residual = 3.30312, No Iterations 1000
time step continuity errors : sum local = 1.23502e+25, global = -5.00345e+08, cumulative = -5.00345e+08




Quote:

Originally Posted by santos (Post 222732)
Your mean Co was 1e-3, but your max Co = 7. Moreover, the fvSolution you showed has relTol 0.01 and 0.1 for most variables.

Jose Santos


barath.ezhilan July 15, 2009 19:32

And I dont think there is much of a problem with the initial settings also. Because i tested the same case with transient Simple Foam and it runs properly. What could be the reason for this discrepancy with respect to TURBFOAM???


Quote:

Originally Posted by santos (Post 222732)
Your mean Co was 1e-3, but your max Co = 7. Moreover, the fvSolution you showed has relTol 0.01 and 0.1 for most variables.

Jose Santos

Quote:

Originally Posted by barath.ezhilan (Post 222730)
Hi santos,

Which settings are you referring to ??

My first post also shows the deltaT settings to be 5E-5 (deltaT 0.00005), and the courant number of the first few time steps was also 1E-3 .


mixer July 15, 2009 22:08

Hi Barath

Is this still happening if you initialize the turbfoam with your simpleFoam results? The simplefoam is a steadystate solver, the transient thing isn't possible with it. Your pressure iterations are taking long time to converge. Try using GAMG solver for Pressure, and the suggestions by Jose for limiting ur courant number.

barath.ezhilan July 16, 2009 06:46

Hi Mandar,

I was referring to the solver transientSimpleFoam, anyways I will change the solver to GAMG and check :)

Quote:

Originally Posted by mixer (Post 222855)
Hi Barath

Is this still happening if you initialize the turbfoam with your simpleFoam results? The simplefoam is a steadystate solver, the transient thing isn't possible with it. Your pressure iterations are taking long time to converge. Try using GAMG solver for Pressure, and the suggestions by Jose for limiting ur courant number.


santos July 16, 2009 06:55

I agree with Mandar, maybe what you are missing is an adequate field initialization. If you dont want to use simpleFoam for that, potentialFoam is also a good option.

Anyway, you could use an even lower deltaT in the first iterations just to make sure your Co stabilizes. Then you can increase your deltaT to a better value.

Regards,
Jose Santos


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