
[Sponsors] 
June 13, 2013, 09:34 
amount of nonorthogonal correction

#1 
Senior Member
Join Date: Mar 2010
Location: Cape Town, SA
Posts: 156
Rep Power: 10 
hi,
can anyone give me any idea how much nonorthogonal correction i should use for various degree's of mesh nonorthogonality? i.e. does anyone have any rules of thumb which they use, or is there a reference which gives a correlation which is useful? attached is the checkMesh log for my mesh: Code:
Checking geometry... Overall domain bounding box (0.130442 0.0549428 0.037182) (0.203 0.0872362 0.13) Mesh (nonempty, nonwedge) directions (1 1 1) Mesh (nonempty) directions (1 1 1) Boundary openness (7.59581e16 3.63295e15 5.78617e16) OK. Max cell openness = 1.68871e14 OK. Max aspect ratio = 231.559 OK. Minumum face area = 7.34819e12. Maximum face area = 1.23274e06. Face area magnitudes OK. Min volume = 7.08378e16. Max volume = 9.05793e10. Total volume = 0.000532329. Cell volumes OK. Mesh nonorthogonality Max: 83.0423 average: 27.5722 *Number of severely nonorthogonal faces: 315461. Nonorthogonality check OK. <<Writing 315461 nonorthogonal faces to set nonOrthoFaces Face pyramids OK. Max skewness = 3.19643 OK. Coupled point location match (average 1.33389e10) OK. Mesh OK. Jonathan 

June 13, 2013, 12:23 

#2  
Member
Daniel Pielmeier
Join Date: Apr 2012
Posts: 96
Rep Power: 7 
Quote:


June 13, 2013, 12:47 

#3  
Senior Member
Join Date: Mar 2010
Location: Cape Town, SA
Posts: 156
Rep Power: 10 
Quote:
regarding the nOrthoCorr loops, i am running a steadystate simulation, so as far as i understand it, i dont need to use additional 'corrector' loops in the SIMPLE loop  i think the iterative nature of the steadystate SIMPLE routine takes care of that? Would you be able to comment on that from your experience (i.e. do i understand it correctly)? Also, does nonorthogonal correction (i.e. nOrthoCorr loops) work without setting the laplacian to some form of corrected / limited scheme? i.e. if i just add nOrthoCorr loops but no correction to the laplacian term, am i actually achieving anything?? Many thanks and regards in advance Cheers jonathan 

June 13, 2013, 13:22 

#4  
Member
Daniel Pielmeier
Join Date: Apr 2012
Posts: 96
Rep Power: 7 
Quote:
That is a good question. I do not know how this is related. However I noticed with a nonorthogonal mesh setting the laplacianSchemes to uncorrected and the snGradSchemes to corrected as well as using leastSquares as gradientScheme lead to quicker convergence. The individual iterations took longer but all in all the simulation time was reduced. 

June 14, 2013, 06:24 

#5  
Senior Member
Join Date: Mar 2010
Location: Cape Town, SA
Posts: 156
Rep Power: 10 
hi billie,
Quote:
Code:
SIMPLE { nNonOrthogonalCorrectors 0; residualControl { p 1e8; Urel 1e8; k 1e8; omega 1e8; } } Code:
// Nonorthogonal pressure corrector loop while (simple.correctNonOrthogonal()) { fvScalarMatrix pEqn ( fvm::laplacian(rAU, p) == fvc::div(phi) ); pEqn.setReference(pRefCell, pRefValue); pEqn.solve(); if (simple.finalNonOrthogonalIter()) { phi = pEqn.flux(); } } Quote:
btw, i would be interested to know where snGradSchemes is used explicitly in the code  i thought that the snGradScheme for the laplacian (which is what i am trying to correct) was specified separately in the laplacian dictionary  i.e. Code:
laplacian(nuEff,Urel) Gauss linear corrected; //uncorrected etc cheers jonathan 

June 14, 2013, 07:00 

#6  
Member
Daniel Pielmeier
Join Date: Apr 2012
Posts: 96
Rep Power: 7 
Quote:
Quote:


Thread Tools  
Display Modes  


Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Some questions about Laplacian with nonorthogonal correction  koderer  OpenFOAM  3  December 12, 2012 18:30 
About nonorthogonal correction in fvclaplacian  7islands  OpenFOAM Running, Solving & CFD  4  December 9, 2012 23:54 
Floating point exception error  Alan  OpenFOAM Running, Solving & CFD  10  April 6, 2012 14:02 
Pressure correction problem  richard_larson  OpenFOAM Running, Solving & CFD  8  October 30, 2008 09:48 
mass flux correction at outflow boundaries  Subhra Datta  Main CFD Forum  2  November 24, 2003 14:11 