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Possible problem with the size of simpleFilter? |
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February 22, 2018, 06:03 |
Possible problem with the size of simpleFilter?
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#1 | |
Senior Member
Canakkale Dardanelspor
Join Date: Aug 2012
Posts: 135
Rep Power: 14 |
Hi,
Please consider a large eddy simulation in which dynamicLagrangian SGS model is used with the test filter simpleFilter. Then please consider the support of the first filter is Delta, assuming cubeRootVolDelta in use. Conventionally, the support of the test filter, simpleFilter herein, is assumed twice the first filter, i.e. 2Delta. Let's further assume a 3-node grid as follows: |--o--|--o--|--o--| where |s are faces, and os are nodes. Let's say the nodes store the following values of an arbitrary variable: 10 (Neighbour-Left), 20 (Owner), 10 (Neighbour-Right). Please assume all other settings are default. The alleged problem is, IMHO, the averaging radius of the test filter, simpleFilter, seems to be different from 2Delta. Below shows the relevant part of the code: Code:
Foam::tmp<Foam::volVectorField> Foam::simpleFilter::operator() ( const tmp<volVectorField>& unFilteredField ) const { correctBoundaryConditions(unFilteredField); tmp<volVectorField> filteredField = fvc::surfaceSum ( mesh().magSf()*fvc::interpolate(unFilteredField) )/fvc::surfaceSum(mesh().magSf()); unFilteredField.clear(); return filteredField; } However, IMHO, 2Delta should result in Quote:
Code:
volSymmTensorField M ( 2.0*sqr(this->delta())*(filter_(magS*S) - 4.0*magSf*Sf) ); The same question was discussed in there with no conclusion. Kind regards, |
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February 24, 2018, 05:20 |
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#2 |
Senior Member
Canakkale Dardanelspor
Join Date: Aug 2012
Posts: 135
Rep Power: 14 |
No SuperPerson? :]
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March 1, 2018, 07:53 |
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#4 |
Senior Member
Canakkale Dardanelspor
Join Date: Aug 2012
Posts: 135
Rep Power: 14 |
It seems this observation is correct, but its prospective effects were presumed to be insignificant to LES solutions (I also agree with this presumption for the moment - tests are needed to prove the opposite): https://bugs.openfoam.org/view.php?id=2865
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filtering, filters, large eddy simulation |
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