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-   -   Bounding epsilon and convergence (http://www.cfd-online.com/Forums/openfoam-solving/113134-bounding-epsilon-convergence.html)

 kirli February 13, 2013 06:06

Bounding epsilon and convergence

Hello Foamers.

I am kind of new in OpenFoam..

I am trying to run SimpleFoam turbulence simulation on a 3D geometry.
It is a kind of pipe with flow splitter. The fluid is water (one phase).

I got this kind of error:

DILUPBiCG: Solving for Ux, Initial residual = 1.96286e-14, Final residual = 1.96286e-14, No Iterations 0
DILUPBiCG: Solving for Uy, Initial residual = 3.56233e-14, Final residual = 3.56233e-14, No Iterations 0
DILUPBiCG: Solving for Uz, Initial residual = 1.38946e-13, Final residual = 1.38946e-13, No Iterations 0
DICPCG: Solving for p, Initial residual = 1, Final residual = 2.63715e+06, No Iterations 1001
time step continuity errors : sum local = 7.66448e+73, global = 1.60172e+66, cumulative = 1.60172e+66
[3] #0 Foam::error::printStack(Foam::Ostream&) in "/opt/openfoam201/platforms/linux64GccDPOpt/lib/libOpenFOAM.so"
[3] #1 Foam::sigFpe::sigHandler(int) in "/opt/openfoam201/platforms/linux64GccDPOpt/lib/libOpenFOAM.so"
[3] #2 in "/lib/libc.so.6"
[3] #3 Foam::PBiCG::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const in "/opt/openfoam201/platforms/linux64GccDPOpt/lib/libOpenFOAM.so"

What is the reason for the negative K?
Thanks

 kirli February 13, 2013 08:39

2 Attachment(s)
I believe that the problem is in the mesh.

I have made a CAD model (solidWorks) and then mesh it in salome. Import it in UNV format to OpenFoam

 shyam June 5, 2013 07:29

Hi Kirli,
Most of us go through this problem of bounding epsilon or omega. Some of things which helped me are the following, which are taken from various threads of CFD-online.

check your mesh using the command checkMesh and look for non-orthogonality, if its between
a. 0 to 50 full corrected scheme is applicable,
b. 50 to 70 limited correction is required,
c. 70 to 80 stability possible, accuracy compromised,
d. above 80 stability very difficult to attain

For case b use the following settings in fvSchemes

{
default faceLimited leastSquares 0.5;
}
laplacianSchemes
{
default Gauss linear limited 0.33;
}