CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > OpenFOAM > OpenFOAM Running, Solving & CFD

Problem with the convergence of the solver

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   July 23, 2015, 06:05
Default Problem with the convergence of the solver
  #1
New Member
 
Join Date: Apr 2015
Posts: 10
Rep Power: 11
DOliveira is on a distinguished road
Hi everyone. I'm new with dealing with OpenFoam. I'm trying to simulate a running turbine. When running pimpleDyMFoam I'm having a problem with convergence I think. my fvSolution is the following:

solvers
{
p
{
solver GAMG;
tolerance 1e-04;
relTol 0.01;
smoother GaussSeidel;
cacheAgglomeration true;
nCellsInCoarsestLevel 10;
agglomerator faceAreaPair;
mergeLevels 1;
}

pFinal
{
solver GAMG;
tolerance 1e-04;
reTol 0;
smoother GaussSeidel;
cacheAgglomeration true;
nCellsInCoarsestLevel 10;
agglomerator faceAreaPair;
mergeLevels 1;
}


cellMotionU
{
solver GAMG;
tolerance 1e-04;
reTol 0;
smoother GaussSeidel;
cacheAgglomeration true;
nCellsInCoarsestLevel 10;
agglomerator faceAreaPair;
mergeLevels 1;
}

"(U|k|omega)"
{
solver PBiCG;
preconditioner DILU;
tolerance 1e-04;
relTol 0.1;
}

"(U|k|omega)Final"
{
$U;
tolerance 1e-04;
relTol 0;
}

k
{
solver PBiCG;
preconditioner DILU;
relTol 0.1;
}

kFinal
{
solver PBiCG;
preconditioner DILU;
tolerance 1e-04;
relTol 0;
}
}

PIMPLE
{
nOuterCorrectors 25;
nCorrectors 1;
nNonOrthogonalCorrectors 0;
pRefCell 0;
pRefValue 0;
}

relaxationFactors
{
fields
{
}
equations
{
"U.*" 1;
"k.*" 1;
"omega.*" 1;
}
}

My deltaT is 0.01 and my maxCo is 0.7
When running pimpleDyMFoam this error appears:

--> FOAM FATAL IO ERROR:
[1] wrong token type - expected Scalar, found on line 0 the word 'nan'

I think this is because the solver can't find convergence to solve the problem.
Can anyone help me or give some hints on how solve this?
Thank you so much
Daniela
DOliveira is offline   Reply With Quote

Old   July 23, 2015, 06:59
Default
  #2
Senior Member
 
anonymous
Join Date: Aug 2014
Posts: 205
Rep Power: 12
ssss is on a distinguished road
We need more information of the error. Second, your fvSolution is awful, please read the documentation of the linear solvers and the PIMPLE argument and use the fvSolution found in the tutorial's testcases
ssss is offline   Reply With Quote

Old   July 23, 2015, 08:13
Default
  #3
New Member
 
Join Date: Apr 2015
Posts: 10
Rep Power: 11
DOliveira is on a distinguished road
Thank you for your answer and help. So I've changed my fvSolution.

solvers
{
p
{
solver GAMG;
tolerance 1e-2;
relTol 0;
smoother DICGaussSeidel;
cacheAgglomeration no;
nCellsInCoarsestLevel 10;
agglomerator faceAreaPair;
mergeLevels 1;
maxIter 50;
}

pFinal
{
solver GAMG;
tolerance 1e-6;
reTol 0;
smoother DICGaussSeidel;
cacheAgglomeration no;
nCellsInCoarsestLevel 10;
agglomerator faceAreaPair;
mergeLevels 1;
}


cellMotionU
{
solver PCG;
preconditioner DIC
tolerance 1e-08;
reTol 0;
}

"(U|k|omega)"
{
solver PBiCG;
preconditioner DILU;
tolerance 1e-05;
relTol 0.1;
}

"(U|k|omega)Final"
{
$U;
tolerance 1e-05;
relTol 0;
}

k
{
solver PBiCG;
preconditioner DILU;
relTol 0.1;
}

kFinal
{
solver PBiCG;
preconditioner DILU;
tolerance 1e-05;
relTol 0;
}
}

PIMPLE
{
correctPhi no;
nOuterCorrectors 3;
nCorrectors 1;
nNonOrthogonalCorrectors 0;
pRefCell 0;
pRefValue 0;
}

relaxationFactors
{
fields
{
}
equations
{
"U.*" 1;
"k.*" 1;
"omega.*" 1;
}
}

The problem now is that the time steps, deltaT, is too small (in the order of 8e-07) and the No Iterations is constatly 0 (zero)
Do you have any idea why this happens?
DOliveira is offline   Reply With Quote

Old   November 9, 2015, 11:25
Default
  #4
Senior Member
 
Join Date: Mar 2015
Posts: 250
Rep Power: 12
KateEisenhower is on a distinguished road
Hi,

did you solve your problem? I had a real quick look at the files. You have a typo: Sometimes you write reTol where it should be relTol. Don't know if it is related to your problem though.

Best regards,

Kate
KateEisenhower is offline   Reply With Quote

Reply

Tags
convergence, dynamic grid, pimpledymfoam


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
[ANSYS Meshing] Help with element size sandri_92 ANSYS Meshing & Geometry 14 November 14, 2018 07:54
convergence of density-based solver for unsteady flow zhengjg Main CFD Forum 0 June 16, 2014 11:37
convergence of density-based solver for unsteady flow zhengjg FLUENT 0 June 16, 2014 10:16
Convergence problem with simpleFoam solver on tilted channel daev OpenFOAM Running, Solving & CFD 1 December 23, 2010 16:20
convergence problem limseokmin FLUENT 3 November 14, 2004 12:43


All times are GMT -4. The time now is 05:27.