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-   -   About the Use of Crank Nicholson scheme (https://www.cfd-online.com/Forums/openfoam/70284-about-use-crank-nicholson-scheme.html)

And November 19, 2009 08:11

About the Use of Crank Nicholson scheme
 
Hello OpenFOAM community,

I'm working on LES of turbulent channel flow and so I'm deeply interested in your discussions and in particular on the validation on the OpenFOAM results.

As I'm concerned in the study of both spatial than temporal discretizations OpenFOAM schemes for LES, my doubt is if selecting the flag CrankNicholson in ddt schemes would mean the correct use of such scheme as in the FOAM ProgrammersGuide P-43 it is said that:

"The Crank Nicholson scheme can be implemented by the mean of implicit and explicit terms:

solve
(
fvm::ddt(phi)
==
kappa*0.5*(fvm::laplacian(phi) + fvc::laplacian(phi))
)
".

If is this so, I'have to rewrite the left hand side of the corresponding UEqn.H exploiting both fvm and fvc operator in order to implement the Crank Nicholson scheme. Otherwise I would not have an effective Crank Nicholson time integration schemes and consequently losing the second order time accuracy.

Any hints about that

Regards

Andrea


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