[barath.ezhilan]

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???