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

What are the definitions of nOuterCorrectors and nCorrectors

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

Like Tree15Likes
  • 4 Post By simt
  • 1 Post By akidess
  • 10 Post By powpawell

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   January 15, 2013, 12:38
Default What are the definitions of nOuterCorrectors and nCorrectors
  #1
Senior Member
 
immortality's Avatar
 
Ehsan
Join Date: Oct 2012
Location: Iran
Posts: 2,208
Rep Power: 26
immortality is on a distinguished road
in rhoPimpleFoam we have below coefficients.what do they refer to?
Code:
nOuterCorrectors 1;
    nCorrectors     2;
immortality is offline   Reply With Quote

Old   January 15, 2013, 19:18
Default
  #2
Senior Member
 
immortality's Avatar
 
Ehsan
Join Date: Oct 2012
Location: Iran
Posts: 2,208
Rep Power: 26
immortality is on a distinguished road
could anyone give a hint?
immortality is offline   Reply With Quote

Old   January 16, 2013, 05:40
Default
  #3
Senior Member
 
Bernhard Linseisen
Join Date: May 2010
Location: Heilbronn
Posts: 183
Blog Entries: 1
Rep Power: 15
Linse is on a distinguished road
Just a hint (I do not know more exact for the moment) : Depending on the number of the different correctors there will be different numbers of iteration cycles within one "timestep".
Putting up this numbers CAN lead to better convergence within the timestep, but it also WILL cause an increase of computational demand...
Linse is offline   Reply With Quote

Old   January 16, 2013, 09:49
Default
  #4
Senior Member
 
immortality's Avatar
 
Ehsan
Join Date: Oct 2012
Location: Iran
Posts: 2,208
Rep Power: 26
immortality is on a distinguished road
thank you bernhard.does anyone knows the difference between them?
immortality is offline   Reply With Quote

Old   January 21, 2013, 15:55
Default
  #5
Member
 
Eric Robertson
Join Date: Jul 2012
Posts: 95
Rep Power: 14
msuaeronautics is on a distinguished road
nCorrectors is the number of times a solution for pressure is attempted within each timestep.

For instance, when nCorrectors = 2, you might see something like this in your output file:

Quote:
DICPCG: Solving for p, Initial residual = 0.00394327, Final residual = 0.00016442, No Iterations 3
time step continuity errors : sum local = 2.90239e-11, global = 1.2422e-13, cumulative = 3.82086e-10
DICPCG: Solving for p, Initial residual = 0.000361647, Final residual = 3.99177e-06, No Iterations 101
time step continuity errors : sum local = 7.04328e-13, global = 1.35611e-13, cumulative = 3.82221e-10
Someone correct me if I'm wrong, but nOuterCorrectors essentially controls how many times you want all of it, including U and p, to be solved for in an iteration. I've never used anything yet other than nOuterCorrectors = 0.
msuaeronautics is offline   Reply With Quote

Old   November 12, 2013, 05:43
Default
  #6
Senior Member
 
Albrecht vBoetticher
Join Date: Aug 2010
Location: Zürich, Swizerland
Posts: 237
Rep Power: 16
vonboett is on a distinguished road
Quote:
Originally Posted by msuaeronautics View Post
nCorrectors is the number of times a solution for pressure is attempted within each timestep.

For instance, when nCorrectors = 2, you might see something like this in your output file:



Someone correct me if I'm wrong, but nOuterCorrectors essentially controls how many times you want all of it, including U and p, to be solved for in an iteration. I've never used anything yet other than nOuterCorrectors = 0.

As far as I see, nOuterCorrectors has an effect, when the viscosity of your fluid changes in dependency to the flow. For example, shear thinning fluids etc., but also when your turbulence model produces a turbulent viscosity that adds to the molecular viscosity.
vonboett is offline   Reply With Quote

Old   November 12, 2013, 05:49
Default
  #7
Member
 
Join Date: Apr 2013
Posts: 32
Rep Power: 12
simt is on a distinguished road
nOuterCorrectors determines no. of iterations over the non-linear coupling. So nOuterCorrections = 1 equals to PISO where the non-linear coupling is neglected.
simt is offline   Reply With Quote

Old   November 29, 2013, 13:34
Default
  #8
Member
 
Jamal
Join Date: May 2012
Location: Freiburg
Posts: 54
Rep Power: 12
aujamal20 is an unknown quantity at this point
Hello Everybody,
It would be very nice if somebody explain nOuterCorrectors and its influence in pimple solver and what is the max limit of its value. For instance, can i use nOuterCorrectors=10 (or higher value) in a simulation using pimple solver.

Thanks
Jamal
aujamal20 is offline   Reply With Quote

Old   November 30, 2013, 08:55
Default
  #9
Senior Member
 
akidess's Avatar
 
Anton Kidess
Join Date: May 2009
Location: Germany
Posts: 1,377
Rep Power: 29
akidess will become famous soon enough
Jamal, the max value for nOuterCorrectors should be 9223372036854775807 (assuming it's of datatype label, and you are on a 64bit system). It's just a counter for a loop, so you can use any number of iterations you require to reach convergence. Of course the more correctors you use the longer your simulation will take, so if you need a large amount of correctors you should ask yourself why convergence is so slow. For more explanation, see the answer by simt.
lpz456 likes this.
__________________
*On twitter @akidTwit
*Spend as much time formulating your questions as you expect people to spend on their answer.
akidess is offline   Reply With Quote

Old   June 13, 2016, 07:31
Default
  #10
New Member
 
Pavel
Join Date: Aug 2014
Posts: 15
Rep Power: 11
powpawell is on a distinguished road
hi Guys,

If you're coming back to this topic, there is an more recent (2015) explanation on this topic:
OpenFOAM guide/The PIMPLE algorithm in OpenFOAM
reza2031, minh khang, Bana and 7 others like this.
powpawell 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



All times are GMT -4. The time now is 12:22.