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

Non-orthogonal correctors

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

Reply
 
LinkBack Thread Tools Display Modes
Old   February 9, 2011, 15:45
Question Non-orthogonal correctors
  #1
New Member
 
Johan Magnusson
Join Date: Oct 2010
Posts: 21
Rep Power: 6
magjohan is on a distinguished road
Okey, lets see how i should explain this. I have a mesh that is (according to my previous knowledge ok regarding orthogonality) but I still want to be sure that the solver dont make to large error on a different mesh, I need therefore an implementation of a non-orthogonal corrector.

Easiest seems to be to use the PISO or SIMPLE loop, which i read corrects for non-orthogonality (http://openfoamwiki.net/index.php/Th...hm_in_OpenFOAM, ... The steps 4 and 5 can be repeated for a prescribed number of time to correct for non-orthogonality. )

The strange thing is that inside the fvSchemes at the "laplacianSchemes":

laplacianSchemes
{
default none;
laplacian((****)),p) Gauss linear corrected;
}

There is something called "Gauss linear correced", which according to the UserGuide means "Explicit non-orthogonal correction". I know also that there are other choices. At the end this leads to my question; is this correction enough or do I have to implement some kind of PISO/SIMPLE loop for correction? It confuses me since it seems to occur some kind of correction already!
magjohan is offline   Reply With Quote

Old   February 10, 2011, 04:30
Default
  #2
Senior Member
 
Gijsbert Wierink
Join Date: Mar 2009
Posts: 382
Rep Power: 9
gwierink is on a distinguished road
Hi Johan,

In fvSolutions you can actually define the number of (non-orthogonal) correctors, so it's probably separated from the schemes like that. in FvSolutions you might have something like
Code:
PISO
{
    nCorrectors     4;
    nNonOrthogonalCorrectors 2;
    pRefCell        0;
    pRefValue       0;
}
__________________
Regards, Gijs
gwierink is offline   Reply With Quote

Old   February 10, 2011, 09:27
Default
  #3
New Member
 
Johan Magnusson
Join Date: Oct 2010
Posts: 21
Rep Power: 6
magjohan is on a distinguished road
Quote:
Originally Posted by gwierink View Post
Hi Johan,

In fvSolutions you can actually define the number of (non-orthogonal) correctors, so it's probably separated from the schemes like that. in FvSolutions you might have something like
Code:
PISO
{
    nCorrectors     4;
    nNonOrthogonalCorrectors 2;
    pRefCell        0;
    pRefValue       0;
}
Actually I dont have something like that, thats because I havent implemented any PISO/SIMPLE loop at this moment. If i refer to my question i asked more whats the difference between the correction that occurs in the PISO loop compared to the one that seems to occur in the "laplacianSchemes". If there arent any difference, is the PISO loop even necessary?
magjohan is offline   Reply With Quote

Old   June 25, 2013, 08:43
Default
  #4
Senior Member
 
Join Date: Mar 2010
Location: Cape Town, SA
Posts: 150
Rep Power: 8
Jonathan is on a distinguished road
Quote:
Originally Posted by magjohan View Post
Actually I dont have something like that, thats because I havent implemented any PISO/SIMPLE loop at this moment. If i refer to my question i asked more whats the difference between the correction that occurs in the PISO loop compared to the one that seems to occur in the "laplacianSchemes". If there arent any difference, is the PISO loop even necessary?
Hi Johan,

did you ever get an answer to this??? i am trying to understand the same thing, although there still doesnt seem to be much around in terms of an explanation ...

best regards
jonathan
Jonathan is online now   Reply With Quote

Old   September 4, 2014, 08:35
Default
  #5
Senior Member
 
Tushar Chourushi
Join Date: Jul 2009
Location: IIT-Indore, India
Posts: 318
Blog Entries: 1
Rep Power: 8
Tushar@cfd is on a distinguished road
Quote:
Originally Posted by magjohan View Post
Actually I dont have something like that, thats because I havent implemented any PISO/SIMPLE loop at this moment. If i refer to my question i asked more whats the difference between the correction that occurs in the PISO loop compared to the one that seems to occur in the "laplacianSchemes". If there arent any difference, is the PISO loop even necessary?
Good Question
I am also struck on to it. Did you find the answer for your query?
Tushar@cfd is offline   Reply With Quote

Old   September 7, 2014, 07:29
Default
  #6
Member
 
Julian Langowski
Join Date: May 2011
Location: Bremen, Germany
Posts: 91
Rep Power: 6
Ruli is on a distinguished road
Hi guys,

as I understand (and I hope, I do not tell you something wrong ):

In fvSolution you define, that you want to use the PISO iteration, the amount of used iterations, ...

In fvSchemes you have to define additionally, on which quantities or terms you want to apply the correction.

So you have to define the nonOrthoCorrection in both files to properly work. Does this answer your question?

Best regards
Julian
__________________
πάντα ῥεῖ - Heraclitus
Ruli is offline   Reply With Quote

Reply

Tags
corrected, non-orthogonality, orthogonality, piso, simple

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
elliptic grid generation (orthogonal) vasu Main CFD Forum 6 March 24, 2011 07:22
[GAMBIT] how to generate orthogonal mesh using GAMBIT? ivanbuz ANSYS Meshing & Geometry 8 October 21, 2009 03:41
Circular Cylinder at low Reynold number mesh and non orthogonal corrections kassiotis OpenFOAM Running, Solving & CFD 6 May 15, 2008 06:07
When and how to apply nonOrthogonal correctors vvqf OpenFOAM Running, Solving & CFD 1 March 22, 2006 06:21
Orthogonal curvilinear coordinates Rudolf Pfeiffer Main CFD Forum 6 December 10, 1998 11:20


All times are GMT -4. The time now is 22:04.