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June 13, 2013, 09:34 |
amount of non-orthogonal correction
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#1 |
Senior Member
Join Date: Mar 2010
Posts: 173
Rep Power: 17 |
hi,
can anyone give me any idea how much non-orthogonal correction i should use for various degree's of mesh non-orthogonality? 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 (non-empty, non-wedge) directions (1 1 1) Mesh (non-empty) directions (1 1 1) Boundary openness (7.59581e-16 -3.63295e-15 5.78617e-16) OK. Max cell openness = 1.68871e-14 OK. Max aspect ratio = 231.559 OK. Minumum face area = 7.34819e-12. Maximum face area = 1.23274e-06. Face area magnitudes OK. Min volume = 7.08378e-16. Max volume = 9.05793e-10. Total volume = 0.000532329. Cell volumes OK. Mesh non-orthogonality Max: 83.0423 average: 27.5722 *Number of severely non-orthogonal faces: 315461. Non-orthogonality check OK. <<Writing 315461 non-orthogonal faces to set nonOrthoFaces Face pyramids OK. Max skewness = 3.19643 OK. Coupled point location match (average 1.33389e-10) OK. Mesh OK. Jonathan |
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June 13, 2013, 12:23 |
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#2 | |
Member
Daniel Pielmeier
Join Date: Apr 2012
Posts: 99
Rep Power: 14 |
Quote:
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June 13, 2013, 12:47 |
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#3 | |
Senior Member
Join Date: Mar 2010
Posts: 173
Rep Power: 17 |
Quote:
regarding the nOrthoCorr loops, i am running a steady-state 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 steady-state 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 non-orthogonal 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 |
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June 13, 2013, 13:22 |
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#4 | |
Member
Daniel Pielmeier
Join Date: Apr 2012
Posts: 99
Rep Power: 14 |
Quote:
That is a good question. I do not know how this is related. However I noticed with a non-orthogonal 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. |
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June 14, 2013, 06:24 |
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#5 | ||
Senior Member
Join Date: Mar 2010
Posts: 173
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hi billie,
Quote:
Code:
SIMPLE { nNonOrthogonalCorrectors 0; residualControl { p 1e-8; Urel 1e-8; k 1e-8; omega 1e-8; } } Code:
// Non-orthogonal 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 |
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June 14, 2013, 07:00 |
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#6 | ||
Member
Daniel Pielmeier
Join Date: Apr 2012
Posts: 99
Rep Power: 14 |
Quote:
Quote:
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