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July 27, 2011, 08:52 
RNG kepsilon model implementation

#1 
Senior Member
Roman Thiele
Join Date: Aug 2009
Location: Eindhoven, NL
Posts: 374
Rep Power: 20 
Hej,
I was wondering why the implementation of the RNG kepsilon model in OpenFOAM looks so much different from the implementation of the standard kepsilon model? Even the kequation looks different, even though that one should be the same. kequation standard keps: Code:
tmp<fvScalarMatrix> kEqn ( fvm::ddt(k_) + fvm::div(phi_, k_)  fvm::Sp(fvc::div(phi_), k_) // missing from the kequation of RNG  fvm::laplacian(DkEff(), k_) == G  fvm::Sp(epsilon_/k_, k_) ); Code:
tmp<fvScalarMatrix> kEqn ( fvm::ddt(k_) + fvm::div(phi_, k_)  fvm::laplacian(DkEff(), k_) == G  fvm::Sp(epsilon_/k_, k_) ); epsequation RNG Code:
// Dissipation equation tmp<fvScalarMatrix> epsEqn ( fvm::ddt(epsilon_) + fvm::div(phi_, epsilon_)  fvm::laplacian(DepsilonEff(), epsilon_) // I expect another term here == (C1_  R)*G*epsilon_/k_ // why is the term R, which is part of the changed C_eps2 constant subtracted from C_eps1 // fvm::SuSp(R*G/k_, epsilon_)  fvm::Sp(C2_*epsilon_/k_, epsilon_) // C2 is a constant here, even though it should be a function of the strainrate tensor );
__________________
~roman 

November 23, 2011, 09:19 

#2  
Senior Member
Vesselin Krastev
Join Date: Jan 2010
Location: University of Tor Vergata, Rome
Posts: 368
Rep Power: 20 
Quote:
Best Regards V. 

June 20, 2018, 08:33 

#3  
Member
Hosein
Join Date: Nov 2011
Location: Germany
Posts: 93
Rep Power: 14 
Quote:
Could you find the reason why the OF version of equations are not similar to the ones of Yakhot et al. 

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rngkepsilon, turbulence model 
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