maybe I'm not right, but in La
 

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

Please post a bug report (in O
 

Please post a bug report (in OpenFOAM-bugs) if you think it is incorrect.

Nope - this is to do with the
 

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

so why we have different formu
 

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

In that case: hmm. What does
 

In that case: hmm. What does the original paper say?

Hrv