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Problem with LaunderSharma compressible turbulence model wrong formulation |
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July 3, 2006, 04:39 |
maybe I'm not right, but in La
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#1 |
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Luca M.
Join Date: Mar 2009
Location: Luzern, Switzerland
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maybe I'm not right, but in LaunderSharma compressible model Epsilon equation, we have that :
... + fvm::SuSp((C3 - 2.0/3.0*C1)*rho_*divU, epsilon_) and in the default turbulenceProperties file we have: C3 = -0.33 I think that we have to change the default value of C3 as: C3 = 0.33 or we have to change the formulation of Epsilon eq. as: ... + fvm::SuSp((- C3 - 2.0/3.0*C1)*rho_*divU, epsilon_) or ... - fvm::SuSp(( C3 + 2.0/3.0*C1)*rho_*divU, epsilon_) because the term C3*rho_*divU has to be positive in RHS of Epsilon equation. I'm right ?!? Luca |
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July 3, 2006, 06:34 |
Please post a bug report (in O
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#2 |
Senior Member
Mattijs Janssens
Join Date: Mar 2009
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Please post a bug report (in OpenFOAM-bugs) if you think it is incorrect.
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July 3, 2006, 06:37 |
Nope - this is to do with the
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#3 |
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Hrvoje Jasak
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Nope - this is to do with the C3 term in engines simulations, where it turns out that a "small positive constant" C3 actually needs to be negative to get the right behaviour. Find an old-ish engines modelling Thesis from Imperial College and you will find the details.
Hrv
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July 3, 2006, 07:21 |
so why we have different formu
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#4 |
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Luca M.
Join Date: Mar 2009
Location: Luzern, Switzerland
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so why we have different formulation in epsilon Eqn. between LaunderSharmaKE and kEpsilon turbulence model, (except f2() term)
kEpsilon C1*G*epsilon_/k_ - fvm::SuSp(((2.0/3.0)*C1 + C3)*rho_*divU, epsilon_) - fvm::Sp(C2*rho_*epsilon_/k_, epsilon_) LaunderSharmaKE C1*G*epsilon_/k_ + fvm::SuSp((C3 - 2.0/3.0*C1)*rho_*divU, epsilon_) - fvm::Sp(C2*f2()*rho_*epsilon_/k_, epsilon_) Luca |
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July 3, 2006, 07:24 |
In that case: hmm. What does
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#5 |
Senior Member
Hrvoje Jasak
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In that case: hmm. What does the original paper say?
Hrv
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Hrvoje Jasak Providing commercial FOAM/OpenFOAM and CFD Consulting: http://wikki.co.uk |
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