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IDProjectCategoryView StatusDate SubmittedLast Update
0000389OpenFOAM[All Projects] Bugpublic2012-01-17 08:532012-01-20 14:46
Reportergregor 
Assigned Tohenry 
PrioritynormalSeverityminorReproducibilityalways
StatusclosedResolutionfixed 
PlatformLinuxOSOtherOS Version(please specify)
Product Version2.0.x 
Target VersionFixed in Version 
Summary0000389: inconsistent way of defining k for compressible Smagorinsky model
DescriptionLooking at the compressible Smagorinsky model i find two way how k gets evaluated.

In the Smagorinsky.C in the updateSubgridScaleFields function:
            volScalarField k(sqr((-b + sqrt(sqr(b) + 4*a*c))/(2*a)));
is used, whereas in the k() function
            (2.0*ck_/ce_)*sqr(delta())*magSqr(dev(symm(gradU)));
is taken.
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-  Notes
(0000941)
henry (manager)
2012-01-20 11:15

Thanks for the bug report.
Resolved in OpenFOAM-2.1.x by commit 09e2f6ca628f33fe8f5ccdd4a09f2492cc969924
(0000942)
gregor (reporter)
2012-01-20 13:38

Are there any reasons / references for the quadratic k equation ? In the literature (ie. Yoshizawa1985,Fureby1996) i find k only as k=c_I*Delta*||D||^2.

thanks
(0000943)
henry (manager)
2012-01-20 13:49

The quadratic form is a natural consequence of the effect of compressibility on the sub-grid stress. Take a look at the description in the header:

        B = 2/3*k*I - 2*nuSgs*dev(D)

    where

        D = symm(grad(U));
        k from rho*D:B + ce*rho*k^3/2/delta = 0
        muSgs = ck*rho*sqrt(k)*delta
(0000945)
gregor (reporter)
2012-01-20 14:29

Ok i found my mistake. Thanks

- Issue History
Date Modified Username Field Change
2012-01-17 08:53 gregor New Issue
2012-01-20 11:15 henry Note Added: 0000941
2012-01-20 11:15 henry Status new => resolved
2012-01-20 11:15 henry Resolution open => fixed
2012-01-20 11:15 henry Assigned To => henry
2012-01-20 13:38 gregor Note Added: 0000942
2012-01-20 13:38 gregor Status resolved => feedback
2012-01-20 13:38 gregor Resolution fixed => reopened
2012-01-20 13:47 henry Status feedback => acknowledged
2012-01-20 13:49 henry Note Added: 0000943
2012-01-20 13:49 henry Status acknowledged => closed
2012-01-20 13:49 henry Resolution reopened => fixed
2012-01-20 14:29 gregor Note Added: 0000945
2012-01-20 14:29 gregor Status closed => feedback
2012-01-20 14:29 gregor Resolution fixed => reopened
2012-01-20 14:46 henry Status feedback => closed
2012-01-20 14:46 henry Resolution reopened => fixed