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September 8, 2010, 11:57 |
about Subgrid-scale model
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#1 |
Member
Kim Yusik
Join Date: Dec 2009
Posts: 39
Rep Power: 16 |
Hi, foamers.
Is there anyone who can recommend me a SGS model for the airfoil case? (of course LES, Reynolds number is less than 100,000) Based on some literature reviews, some works are done with 'Dynamic smagorinsky' model and some works are done with 'Mixed-sclae model' ( Sagaut, P. 1996 : Numerical simulations of separated flows with subgrid models) or 'Mixed-time model' (Inagaki et al. 2005 : A Mixed-time-scale SGS model with fixed model - parameters for practical LES). I've checked 'dynamic Smagorinsky model' in openfoam but one line (below) is ambiguous in the dynSmagorinsky.C file. 00060 dimensionedScalar MMMM = average(magSqr(MM)); here I don't understand what 'average' means. Does it mean averaging in whole domain? if it means averaging whole domain, this model doesn't seem so attractive since original model averaged only in homogeneous directions. So I tried to look for 'Mixed-scale model' or 'Mixed-time model' in openfoam but these two models are not implemented yet. I am also wondering is there anyone who implemented these two models into openfoam. To sum, which sgs model do you recommend for the airfoil case ? what is the 'average' mean in the 'dynamic Smagorinsky model' ? Is there anyone who implement 'Mixed -scale model' or 'Mixed-time model' into the openfoam ? Thanks in advance Yusik |
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September 9, 2010, 10:26 |
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#2 | |
Senior Member
Alberto Passalacqua
Join Date: Mar 2009
Location: Ames, Iowa, United States
Posts: 1,912
Rep Power: 36 |
Quote:
Similarly, the mixed-time model simply redefines the SGS viscosity as a function of a certain time-scale, with some theoretical advantage. You could implement it by starting from an existing model (like the dynamic one) in OF. Best,
__________________
Alberto Passalacqua GeekoCFD - A free distribution based on openSUSE 64 bit with CFD tools, including OpenFOAM. Available as in both physical and virtual formats (current status: http://albertopassalacqua.com/?p=1541) OpenQBMM - An open-source implementation of quadrature-based moment methods. To obtain more accurate answers, please specify the version of OpenFOAM you are using. |
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September 12, 2010, 13:47 |
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#3 |
Member
Kim Yusik
Join Date: Dec 2009
Posts: 39
Rep Power: 16 |
wrong questions sorry
Last edited by impecca; September 14, 2010 at 06:33. Reason: wrong questions |
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December 20, 2013, 06:54 |
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#4 | |
Senior Member
Jian Zhong
Join Date: Feb 2012
Location: Birmingham
Posts: 109
Rep Power: 14 |
Quote:
Could you suggest a related tutorial case? I am tring to using the dynamic Smagorinsky model, but without success. My best regards, Jian |
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December 20, 2013, 10:36 |
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#5 | |
Senior Member
Jian Zhong
Join Date: Feb 2012
Location: Birmingham
Posts: 109
Rep Power: 14 |
Quote:
Could you suggest a related tutorial case? I am tring to using the dynamic Smagorinsky model, but without success. My best regards, Jian |
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