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

Continuity. Stop critertion of PISO and SIMPLE in OpenFOAM solvers.

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

Like Tree1Likes
  • 1 Post By niklas

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   September 20, 2010, 16:12
Default Continuity. Stop critertion of PISO and SIMPLE in OpenFOAM solvers.
  #1
Senior Member
 
Claus Meister
Join Date: Aug 2009
Location: Wiesbaden, Germany
Posts: 241
Rep Power: 18
idrama is on a distinguished road
Hallo Foamers!

I have a question related to OpenFOAM solvers with SIMPLE or PISO loop. Why was as stop criterion the number of iteration used or implemented,respectively, and not a number of accuracy, e.g. 1e-10 (sum,global,cumulative)? Has this a specific reason?

Cheers!
idrama is offline   Reply With Quote

Old   September 20, 2010, 17:53
Default
  #2
Super Moderator
 
niklas's Avatar
 
Niklas Nordin
Join Date: Mar 2009
Location: Stockholm, Sweden
Posts: 693
Rep Power: 29
niklas will become famous soon enoughniklas will become famous soon enough
Quote:
Originally Posted by idrama View Post
Why was as stop criterion the number of iteration used or implemented,respectively, and not a number of accuracy, e.g. 1e-10 (sum,global,cumulative)?
Where?

Do you know you can add an option to the SIMPLE dictionary in system/fvSolution
convergence 1.0e-5;
niklas is offline   Reply With Quote

Old   September 21, 2010, 03:15
Default
  #3
Senior Member
 
Claus Meister
Join Date: Aug 2009
Location: Wiesbaden, Germany
Posts: 241
Rep Power: 18
idrama is on a distinguished road
I did not know that! Honestly, I am a bit surprised. How can I set up such criterion? In guides and documents, I have nothing read about this, anywhere! Where I can find it?
idrama is offline   Reply With Quote

Old   September 21, 2010, 03:50
Default
  #4
Super Moderator
 
niklas's Avatar
 
Niklas Nordin
Join Date: Mar 2009
Location: Stockholm, Sweden
Posts: 693
Rep Power: 29
niklas will become famous soon enoughniklas will become famous soon enough
if you are using simpleFoam it is already there, so you just have to add it to the SIMPLE dictionary.

Code:
SIMPLE
{
    nNonOrthogonalCorrectors 1;
    convergence              1.0e-8;
}
a good place to start would be the source code of the application you are using (in this case simpleFoam)
where you will find initConvergenceCheck.H

Code:
// initialize values for convergence checks

    scalar eqnResidual = 1, maxResidual = 0;
    scalar convergenceCriterion = 0;

    simple.readIfPresent("convergence", convergenceCriterion);
so you see that convergence is set to 0 if you dont define it.

and then the convergenceCheck.H which is the last include of the iteration-loop

Code:
// check convergence

if (maxResidual < convergenceCriterion)
{
    Info<< "reached convergence criterion: " << convergenceCriterion << endl;
    runTime.writeAndEnd();
    Info<< "latestTime = " << runTime.timeName() << endl;
}
hawkeye321 likes this.
niklas is offline   Reply With Quote

Old   September 21, 2010, 04:26
Default
  #5
Senior Member
 
Claus Meister
Join Date: Aug 2009
Location: Wiesbaden, Germany
Posts: 241
Rep Power: 18
idrama is on a distinguished road
Thank you for you posted. I will looking for it!
idrama is offline   Reply With Quote

Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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 Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
continuityErrs.h, coninuity equation, automatic stop are reaching continuity idrama OpenFOAM 0 September 20, 2010 16:09
SIMPLE, SIMPLER or PISO? Gem Leku Main CFD Forum 7 October 24, 2007 12:20
SIMPLE and PISO Aditya Main CFD Forum 5 April 1, 2006 19:52
diffrence beetwen SIMPLE and PISO grzes FLUENT 0 January 29, 2006 06:57
PISO vs. SIMPLE benedikt flurl Main CFD Forum 2 April 14, 2005 07:54


All times are GMT -4. The time now is 05:33.