# nonorthogonal corrections, when and where to apply?

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 February 7, 2012, 07:00 nonorthogonal corrections, when and where to apply? #1 New Member   Andrej Join Date: Feb 2012 Posts: 2 Rep Power: 0 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

 February 7, 2012, 10:13 #2 New Member   Join Date: Jun 2009 Posts: 27 Rep Power: 10 I am not an expert but I think the non-orthogonal 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 non-orthogonal 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 New Member   Andrej Join Date: Feb 2012 Posts: 2 Rep Power: 0 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
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 Originally Posted by andrejkoch 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
I think solution of the pressure equation with non-orthogonal correction should finish first before solving the transport equation. Once you know the corrected velocity field then you can solve transport equation of T. I suppose you can apply the correction to the diffusion term of T as well ( any implicit laplacian or snGrad term on a grid with skewed cells will benefit from multiple corrections ). So in case of T , i guess the correction is only applied once. It maybe that the pressure equation benefits more from multiple corrections depending on the skeweness of the grid.
Hope it helps