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

SimpleFoam - Interpretation of Residuals

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Display Modes
Old   February 7, 2013, 08:36
Default SimpleFoam - Interpretation of Residuals
  #1
Senior Member
 
Sören
Join Date: Mar 2012
Posts: 102
Rep Power: 5
despaired student is on a distinguished road
Hi,

I need comments on my residuals-plots. They look pretty ...linear. I've never had such residuallines before. How to interpretate them and how does it come?

The configuration files are the following:

ControlDict:
Quote:
FoamFile
{
version 2.0;
format ascii;
class dictionary;
location "system";
object controlDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

application simpleFoam;

startFrom latestTime;

startTime 0;

stopAt endTime;

endTime 6000;

deltaT 1;

writeControl timeStep;

writeInterval 50;

purgeWrite 0;

writeFormat ascii;

writePrecision 6;

writeCompression on;

timeFormat general;

timePrecision 6;

runTimeModifiable true;
fvSchemes:
Quote:
FoamFile
{
version 2.0;
format ascii;
class dictionary;
location "system";
object fvSchemes;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

ddtSchemes
{
default steadyState;
}

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

divSchemes
{
default none;
div(phi,U) Gauss linear; //upwind;
div(phi,k) Gauss linear;
div(phi,epsilon) Gauss linear;
div(phi,R) Gauss linear;
div(R) Gauss linear;
div(phi,nuTilda) Gauss linear;
div((nuEff*dev(T(grad(U))))) 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(DREff,R) Gauss linear corrected;
laplacian(DnuTildaEff,nuTilda) Gauss linear corrected;
}

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

snGradSchemes
{
default corrected;
}

fluxRequired
{
default no;
p ;
}
fvSolution:
Quote:
FoamFile
{
version 2.0;
format ascii;
class dictionary;
location "system";
object fvSolution;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

solvers
{
p
{
solver PCG;
preconditioner DIC;
tolerance 0; //1e-06
relTol 0.001; //0.01
}

U
{
solver PBiCG;
preconditioner DILU;
tolerance 0; //1e-05
relTol 0.001; //0.1
}

k
{
solver PBiCG;
preconditioner DILU;
tolerance 1e-05;
relTol 0.1;
}

epsilon
{
solver PBiCG;
preconditioner DILU;
tolerance 1e-05;
relTol 0.1;
}

R
{
solver PBiCG;
preconditioner DILU;
tolerance 1e-05;
relTol 0.1;
}

nuTilda
{
solver PBiCG;
preconditioner DILU;
tolerance 1e-05;
relTol 0.1;
}
}

SIMPLE
{
nNonOrthogonalCorrectors 2; //0

residualControl
{
p 1e-12; // 1e-3
U 1e-12; // 1e-4
"(k|epsilon|omega)" 1e-3;
}
}

relaxationFactors
{
p 0.3;
U 0.7;
k 0.7;
epsilon 0.7;
R 0.7;
nuTilda 0.7;
}
Attached Images
File Type: jpg 1 Segment.jpg (30.7 KB, 33 views)
File Type: jpg 2 Segmente.jpg (30.4 KB, 28 views)
File Type: jpg 3Segmente.jpg (28.7 KB, 26 views)
despaired student is offline   Reply With Quote

Old   February 8, 2013, 03:06
Default
  #2
Senior Member
 
sfigato's Avatar
 
Marco Longhitano
Join Date: Jan 2013
Location: Aachen
Posts: 103
Rep Power: 4
sfigato is on a distinguished road
Send a message via Skype™ to sfigato
Hi Soren,

I am dealing with the same issue...your residuals are pretty low, though they do not reach the steady state (i think so). They are going on to decrease. I suggest to you to let the simulation run for more iterations!

Regards
Marco
sfigato is offline   Reply With Quote

Old   February 8, 2013, 03:21
Default
  #3
Senior Member
 
sfigato's Avatar
 
Marco Longhitano
Join Date: Jan 2013
Location: Aachen
Posts: 103
Rep Power: 4
sfigato is on a distinguished road
Send a message via Skype™ to sfigato
Hi Soren,


Why have you used a tolerance equal to 0 for U and p?

Regards
Marco
sfigato is offline   Reply With Quote

Old   February 8, 2013, 08:39
Default
  #4
Senior Member
 
Sören
Join Date: Mar 2012
Posts: 102
Rep Power: 5
despaired student is on a distinguished road
My superwiser told me that I should use for U and p a tolerance of 0.
despaired student is offline   Reply With Quote

Reply

Thread Tools
Display Modes

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 On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Laminar simpleFoam and inviscid simpleFoam herenger OpenFOAM Running, Solving & CFD 7 July 11, 2013 06:27
SimpleFoam: High residuals after increase in Reynolds Number JasonG OpenFOAM Running, Solving & CFD 20 January 10, 2013 14:09
interFoam vs. simpleFoam channel flow comparison DanM OpenFOAM Running, Solving & CFD 11 January 5, 2013 07:21
judging convergence through residuals MachZero Main CFD Forum 7 December 25, 2012 13:18
Trying to run a benchmark case with simpleFoam spsb OpenFOAM 3 February 24, 2012 10:07


All times are GMT -4. The time now is 03:52.