[nzy102]

Hi, there:

I think I found a bug in liencubiclowRe model c file. The definition of nonlinearstress is as follows:

#################################################

nonlinearStress
(
"nonlinearStress",
symm
(
// quadratic terms
pow(k_, 3.0)/sqr(epsilon_)*
(
Ctau1/fEta*
(
(gradU & gradU)
+ (gradU & gradU)().T()
)
+ Ctau2/fEta*(gradU & gradU.T())
+ Ctau3/fEta*(gradU.T() & gradU)
)
// cubic term C4
- 20.0*pow(k_, 4.0)/pow(epsilon_, 3.0)*
pow(Cmu, 3.0)*
(
((gradU & gradU) & gradU.T())
+ ((gradU & gradU.T()) & gradU.T())
- ((gradU.T() & gradU) & gradU)
- ((gradU.T() & gradU.T()) & gradU)
)
// cubic term C5, explicit part
+ min
(
C5viscosity,
dimensionedScalar("0", C5viscosity.dimensions(), 0.0)
)*gradU
)
)
#################################################

here is the definitio of the Reynolds Stress:

#################################################

tmp<volsymmtensorfield> LienCubicKELowRe::R() const
{
return tmp<volsymmtensorfield>
(
new volSymmTensorField
(
IOobject
(
"R",
runTime_.timeName(),
mesh_,
IOobject::NO_READ,
IOobject::NO_WRITE
),
((2.0/3.0)*I)*k_ - nut_*twoSymm(gradU) + nonlinearStress,
k_.boundaryField().types()
)
);
}
###############################################

I think the correct definition should be:
((2.0/3.0)*I)*k_ - nut_*twoSymm(gradU) + nonlinearStress*fmu

where fmu is the damping function.

Reference:

Lien, F.S., Chen, W.L., Leschziner, M.A., 1996. Low-Reynolds-number eddy-viscosity modeling based on non-linear stress-strain/vorticity relations. Engineering Turbulence Modelling and Experiments 3 (Edited by Rodi, W. and Bergeles, G.), 91-100. Elsevier Science Publishers.

Etemad, S., et al., 2006. Turbulent flow and heat transfer in a square-sectioned U bend. Progress in compuational fluid dynamics 6, 89-100.