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IDProjectCategoryView StatusLast Update
0003292OpenFOAMBugpublic2019-06-14 15:00
ReportertnnandiAssigned To 
PrioritylowSeverityminorReproducibilityalways
Status newResolutionopen 
PlatformGNU/LinuxOSUbuntuOS Version15.04
Product Version6 
Fixed in Version 
Summary0003292: Incorrect filtering and expression in LES dynamicKEqnModel
DescriptionIn the referred paper "Kim, W and Menon, S. (1995). A new dynamic one-equation subgrid-scale model for large eddy simulation. In 33rd Aerospace Sciences Meeting and Exhibit, Reno, NV, 1995.", the expression for L_ij, M_ij and Ck (or Cv as in the paper) are given in equations 14 to 16. The corresponding expressions in the code (dynamicKEqn.C) involve an additional filter,
e.g. for M_ij, lines 50-53 in the code are:

   const volSymmTensorField MM
    (
        simpleFilter_(-2.0*this->delta()*sqrt(KK)*filter_(D))
    );

, but we think the simpleFilter_ used in the front is not required as per the expression in the paper (Eq. 15). Also, in the formulation found in the code, the two terms on the RHS of Eqn 15 are different from the above expression.

We think this usage of the additional filter can have an additional damping effect on the test scale motions.

TagsNo tags attached.

Activities

henry

2019-06-12 23:31

manager   ~0010516

Do you have any cases or results which demonstrate that the additional filter reduces the accuracy of the model? My understanding is that it was added to improve stability and range of application but if you can provide results for a range of cases which show that it is not needed and/or not appropriate I would be happy to remove it.

> Also, in the formulation found in the code, the two terms on the RHS of Eqn 15 are different from the above expression.

What other changes do you want to make to the model? Do you have a complete and tested alternative implementation?

tnnandi

2019-06-13 00:45

reporter   ~0010517

I'll upload comparison cases within a couple of days. I guessed that the use of the additional filter must be for enhancing stability, but couldn't get why the RHS of Eqn 15 was changed significantly.

Issue History

Date Modified Username Field Change
2019-06-12 22:15 tnnandi New Issue
2019-06-12 23:31 henry Note Added: 0010516
2019-06-12 23:32 henry Priority high => low
2019-06-12 23:32 henry Severity major => minor
2019-06-13 00:45 tnnandi Note Added: 0010517