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IDProjectCategoryView StatusDate SubmittedLast Update
0000462OpenFOAM[All Projects] Bugpublic2012-03-15 10:222012-04-13 16:07
Reportervkrastev 
Assigned ToSergio 
PrioritynormalSeveritymajorReproducibilityalways
StatusresolvedResolutionfixed 
PlatformLinuxOSUbuntuOS Version10.10
Product Version2.1.x 
Target VersionFixed in Version 
Summary0000462: Sign inconsistency in the compressible Launder-Sharma k-epsilon model
DescriptionChecking the epsilon transport equation in the Launder-Sharma low-Re model I've found a clear inconsistency in the C3 constant sign (at least it is there in the OF-2.1.0 release, I don't know if it has been already fixed in 2.1.x).

The following is the (correct) compressibility production term in the standard k-epsilon model implementation:

- fvm::SuSp(((2.0/3.0)*C1_ + C3_)*rho_*divU, epsilon_)

As you can see, the term multiplied by C1 enters with a negative sign, while the term multiplied by C3 actually becomes positive, as in OF C3 is equal to -0.33 while the correct constant value in the RHS of the epsilon equation should be +0.33.

This is the same (incorrect) term in the Launder-Sharma model:

+ fvm::SuSp((C3_ - 2.0/3.0*C1_)*rho_*divU, epsilon_)

The C1 term is again negative, but so it is the C3 one as in OF +C3=-0.33.

So, I don't know what is the real influence of such an error, but to me this is clearly a bug.

Regards

V.
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(0001238)
Sergio (developer)
2012-04-13 16:06

Resolved in commit:
4a9bb59ec8e53f79d1a53220f16be4f334f407cb

- Issue History
Date Modified Username Field Change
2012-03-15 10:22 vkrastev New Issue
2012-04-13 16:03 Sergio Status new => resolved
2012-04-13 16:03 Sergio Resolution open => fixed
2012-04-13 16:03 Sergio Assigned To => Sergio
2012-04-13 16:06 Sergio Note Added: 0001238
2012-04-13 16:06 Sergio Status resolved => feedback
2012-04-13 16:06 Sergio Resolution fixed => reopened
2012-04-13 16:07 Sergio Status feedback => resolved
2012-04-13 16:07 Sergio Resolution reopened => fixed