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

UEqn.relax()

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

Like Tree11Likes
  • 1 Post By mugi
  • 1 Post By giack
  • 3 Post By santiagomarquezd
  • 2 Post By Bernhard
  • 1 Post By giack
  • 3 Post By cfdonline2mohsen

Reply
 
LinkBack Thread Tools Display Modes
Old   December 7, 2011, 10:35
Default UEqn.relax()
  #1
New Member
 
Maike
Join Date: Dec 2010
Posts: 8
Rep Power: 6
mugi is on a distinguished road
In the PIMPLE algorithm the momentum equation is defined and afterwards used by UEqun.relax(). As far as I could figure out this means that an underrelaxation is applied, but what does this relax do exactly or where is it defined in the code?

Thanks for any help!
Maike.
immortality likes this.
mugi is offline   Reply With Quote

Old   June 20, 2013, 05:11
Default
  #2
Member
 
Join Date: Mar 2013
Posts: 86
Rep Power: 4
giack is on a distinguished road
Hi,
Do you find the answer at your question? I have the same question. Moreover in my fvSolution file I don't specify any under relaxation factor..
Thanks
immortality likes this.
giack is offline   Reply With Quote

Old   July 2, 2013, 23:14
Default
  #3
Senior Member
 
santiagomarquezd's Avatar
 
Santiago Marquez Damian
Join Date: Aug 2009
Location: Santa Fe, Santa Fe, Argentina
Posts: 418
Rep Power: 15
santiagomarquezd will become famous soon enough
http://foam.sourceforge.net/docs/cpp/a04763_source.html, line 524
__________________
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   July 3, 2013, 01:41
Default
  #4
Senior Member
 
immortality's Avatar
 
Ehsan
Join Date: Oct 2012
Location: Iran
Posts: 2,205
Rep Power: 17
immortality is on a distinguished road
it isn't clear how the relaxation is applied even in the code.
Where alpha is defined?
Can we set it and whats alpha at all?
How relaxation is applied?
__________________
Injustice Anywhere is a Threat for Justice Everywhere.Martin Luther King.
To Be or Not To Be,Thats the Question!
The Only Stupid Question Is the One that Goes Unasked.
immortality is offline   Reply With Quote

Old   July 3, 2013, 01:51
Default
  #5
Senior Member
 
Bernhard
Join Date: Sep 2009
Location: Delft
Posts: 790
Rep Power: 12
Bernhard is on a distinguished road
See line 658 of the same file, the relax() member function without argument is defined. Then, the parameter are read from a file, as here http://foam.sourceforge.net/docs/cpp...ce.html#l00313

Note that on the docs, you can search for member functions that you want to find (I used it on "equationRelaxationFactor")
cfdonline2mohsen and ScarFace like this.
Bernhard is offline   Reply With Quote

Old   July 3, 2013, 05:17
Default
  #6
Member
 
Join Date: Mar 2013
Posts: 86
Rep Power: 4
giack is on a distinguished road
So if I don't specify any relaxation factor in fvSolution file the relaxation is not applied to equation,it's right?
immortality likes this.
giack is offline   Reply With Quote

Old   July 3, 2013, 08:39
Default
  #7
Senior Member
 
immortality's Avatar
 
Ehsan
Join Date: Oct 2012
Location: Iran
Posts: 2,205
Rep Power: 17
immortality is on a distinguished road
its not obvious enough to find out how automatically this relaxation is implemented yet,how can avoid relaxation?
__________________
Injustice Anywhere is a Threat for Justice Everywhere.Martin Luther King.
To Be or Not To Be,Thats the Question!
The Only Stupid Question Is the One that Goes Unasked.

Last edited by immortality; July 3, 2013 at 15:10.
immortality is offline   Reply With Quote

Old   July 3, 2013, 13:06
Default
  #8
Senior Member
 
cfdonline2mohsen's Avatar
 
Mohsen KiaMansouri
Join Date: Jan 2010
Location: CFD Lab
Posts: 118
Rep Power: 7
cfdonline2mohsen is on a distinguished road
Thanks Santiago & Bernhard
If you don't specify any under relaxation factor then the default is zero
Code:
00099         eqnRelaxDefault_ = 
00100         eqnRelaxDict_.lookupOrDefault<scalar>("default", 0.0);
immortality, giack and ScarFace like this.
__________________
“If you have an apple and I have an apple and we exchange these apples then you and I will still each have one apple. But if you have an idea and I have an idea and we exchange these ideas, then each of us will have two ideas.”
cfdonline2mohsen 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 07:45.