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

Does anyone knows about momentumPredictor in rhoPimoleFoam?

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

Like Tree8Likes
  • 1 Post By santiagomarquezd
  • 1 Post By wyldckat
  • 6 Post By santiagomarquezd

Reply
 
LinkBack Thread Tools Display Modes
Old   February 21, 2013, 09:18
Default Does anyone knows about momentumPredictor in rhoPimoleFoam?
  #1
Senior Member
 
immortality's Avatar
 
Ehsan
Join Date: Oct 2012
Location: Iran
Posts: 2,173
Rep Power: 16
immortality is on a distinguished road
what does momentumPredictor do in PIMPLE dictionary?have anyone some information about it?
Code:
PIMPLE
{
    momentumPredictor yes;
    nOuterCorrectors 7;
    nCorrectors     4;
    nNonOrthogonalCorrectors 1;
    rhoMin          rhoMin [ 1 -3 0 0 0 ] 0.5;
    rhoMax          rhoMax [ 1 -3 0 0 0 ] 7.5;
    convergence        1e-16;

residualControl
    {
        "(U|k|omega)"
        {
            relTol          0;
            tolerance       0.00000000001;
        }
    }
}
immortality is offline   Reply With Quote

Old   February 26, 2013, 18:00
Default
  #2
Senior Member
 
immortality's Avatar
 
Ehsan
Join Date: Oct 2012
Location: Iran
Posts: 2,173
Rep Power: 16
immortality is on a distinguished road
any answer is appreciated!
immortality is offline   Reply With Quote

Old   March 1, 2013, 15:55
Default
  #3
Senior Member
 
santiagomarquezd's Avatar
 
Santiago Marquez Damian
Join Date: Aug 2009
Location: Santa Fe, Santa Fe, Argentina
Posts: 416
Rep Power: 14
santiagomarquezd will become famous soon enough
It enables/disables the solution of the momentum predictor.

Regards
akidess likes this.
__________________
Santiago MÁRQUEZ DAMIÁN, Ph.D.
Post-doctoral Fellow
Research Center for Computational Mechanics (CIMEC) - CONICET/FICH-UNL
T.E.: 54-342-4511594 Ext. 1005
Güemes 3450 - (3000) Santa Fe
Santa Fe - Argentina
http://www.cimec.org.ar
santiagomarquezd is offline   Reply With Quote

Old   March 2, 2013, 00:26
Default
  #4
Senior Member
 
immortality's Avatar
 
Ehsan
Join Date: Oct 2012
Location: Iran
Posts: 2,173
Rep Power: 16
immortality is on a distinguished road
thanks.whats the effect of predictor on solution,accuracy and stability in unsteady compressible problems?
immortality is offline   Reply With Quote

Old   March 2, 2013, 07:22
Default
  #5
Super Moderator
 
Bruno Santos
Join Date: Mar 2009
Location: Lisbon, Portugal
Posts: 7,328
Blog Entries: 32
Rep Power: 72
wyldckat is a jewel in the roughwyldckat is a jewel in the roughwyldckat is a jewel in the roughwyldckat is a jewel in the rough
Quote:
Originally Posted by immortality View Post
thanks.whats the effect of predictor on solution,accuracy and stability in unsteady compressible problems?
A quick Google search lead me to this:
Quote:
Originally Posted by http://openfoamwiki.net/index.php/The_PISO_algorithm_in_OpenFOAM
  • Solve the momentum predictor
solve (UEqn == -fvc::grad(p));
This looks so simple that it's probably explained in any good CFD book?
immortality likes this.
wyldckat is offline   Reply With Quote

Old   March 2, 2013, 09:49
Default
  #6
Senior Member
 
santiagomarquezd's Avatar
 
Santiago Marquez Damian
Join Date: Aug 2009
Location: Santa Fe, Santa Fe, Argentina
Posts: 416
Rep Power: 14
santiagomarquezd will become famous soon enough
Hi, the momentum predictor is a first approximation of the velocity field obtained from the solution of a momentum equation assembled with the previous time-step pressure field. This velocity doesn't fulfill the restriction given by the continuity equation which is achieved laterly by the PISO method. Sometimes you can avoid the solution of the momPred saving time, but it can lead to a bad convergence in the PISO loop. Is a user's choice based in the problem behavior.

Regards.
__________________
Santiago MÁRQUEZ DAMIÁN, Ph.D.
Post-doctoral Fellow
Research Center for Computational Mechanics (CIMEC) - CONICET/FICH-UNL
T.E.: 54-342-4511594 Ext. 1005
Güemes 3450 - (3000) Santa Fe
Santa Fe - Argentina
http://www.cimec.org.ar
santiagomarquezd 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



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