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February 7, 2012, 07:00 
nonorthogonal corrections, when and where to apply?

#1 
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Andrej
Join Date: Feb 2012
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Hello!
I found that it is necessary to apply nonorthogonal corrections when working with skew meshes. What exactly are the necessary steps? Do I merely add a loop Code:
for (int nonOrth=0; nonOrth<nNonOrthCorr; nonOrth++){ solve(...); } The Programmer's guide mentions that snGradCorrection is also needed on nonorthogonal meshes. But snGradCorrection isn't called in any of the solvers. What if I solve several equations in a segregated solver? Do I run the loop on each individual equation: Code:
for (int nonOrth=0; nonOrth<nNonOrthCorr; nonOrth++){ Eqn1.solve(); } for (int nonOrth=0; nonOrth<nNonOrthCorr; nonOrth++){ Eqn2.solve(); } Code:
for (int nonOrth=0; nonOrth<nNonOrthCorr; nonOrth++){ Eqn1.solve(); Eqn2.solve(); } TEqn.solve() is added *outside* the nonorthogonal corrections loop. Why? Is TEqn not affected by nonorthogonality? If you know a good explanation for understanding the details of nonorthogonal corrections, please tell. Thank you Andrej 

February 7, 2012, 10:13 

#2 
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I am not an expert but I think the nonorthogonal corrections are applied as implicit and explicit term in the discretization of the equation to be solved. Look into Jasaak's thesis to see how it is done. For example the poison pressure equation solution has a laplacian term which can benefit from nonorthogonal correction. So whenever the loop is called the explicit correction term is modified thereby refining the solution. It is all automatic so you don't have to add a snGradCorrection term yourself, just specify that correction should be applied in the discretized equation in fvSchemes.
Hope it helps. 

February 7, 2012, 11:45 

#3 
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Andrej
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Daniel, thank you. That answers my first question.
Now what if I have to solve a sequence of equations? And why is TEqn not corrected in the example from the Wiki? Thank you Andrej 

February 7, 2012, 17:36 

#4  
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Quote:
Hope it helps Wiki link: http://www.cfdonline.com/Wiki/Diffusion_term 

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