[giammy92]

My results of Cl, for every BC's that i have tried, still remain about 1.5, but Cl must be about 1.25. How is possible that? I have a mesh very fine with y+ less than 1. I've found a discussion Why Menter's SST model low-Re issue has not been seriously investigated? in which is suggested to use follow bc's for wall:
-k, fixed value very small
-nut, calculated
-omega, omegawallfunction
For patch FAR_FIELD i've use:
-k, turbulentIntensityKineticEnergyInlet with value uniform calculated: 1.5(U*I)^2
-nut, calculated with value uniform 0;
-omega, turbulentMixingLengthFrequencyInlet with value uniform: 1/mu*rho*k*(mut/mu)^-1
and mixinglenght calculated from this formula http://www.cfd-online.com/Wiki/Turbulence_length_scale
My angle of attack is 13° so:
liftDir (-0.22495 0.97437 0);
dragDir (0.97437 0.22495 0);
Questions:
1) Do you validate these bc's and formula for my case?
2)Why did i have about same results of Cl with different bc's like nutkwallfunction, nutuspaldingwallfunction, nutlowre for nut and kqrwallfunction for k?
3)Could be the cause in fvschemes or fvsolution?
Please, help me, i have wasted a lot of time for this problem, i can't imagine what else i have to change!!

[giammy92]

ddtSchemes
{
default steadyState;
}

gradSchemes
{
default Gauss linear;
}

divSchemes
{
default none;
div(phi,U) bounded Gauss linearUpwind grad(U);
div(phi,k) bounded Gauss upwind;
div(phi,omega) bounded Gauss upwind;
div((nuEff*dev2(T(grad(U))))) Gauss linear;
}

laplacianSchemes
{
default Gauss linear corrected;
}

interpolationSchemes
{
default linear;
}

snGradSchemes
{
default corrected;
}

wallDist
{
method meshWave;
}



solvers
{
p
{
solver GAMG;
tolerance 1e-06;
relTol 0.1;
smoother GaussSeidel;
nPreSweeps 0;
nPostSweeps 2;
cacheAgglomeration true;
nCellsInCoarsestLevel 10;
agglomerator faceAreaPair;
mergeLevels 1;
}

U
{
solver smoothSolver;
smoother GaussSeidel;
nSweeps 2;
tolerance 1e-08;
relTol 0.1;
}

k
{
solver smoothSolver;
smoother GaussSeidel;
tolerance 1e-8;
relTol 0.1;
nSweeps 1;
}

omega
{
solver smoothSolver;
smoother GaussSeidel;
tolerance 1e-8;
relTol 0.1;
nSweeps 1;
}
}

SIMPLE
{
nNonOrthogonalCorrectors 0;
pRefCell 0;
pRefValue 0;

residualControl
{
p 1e-5;
U 1e-5;
k 1e-5;
omega 1e-5;
}
}

relaxationFactors
{
fields
{
p 0.3;
}
equations
{
U 0.5;
k 0.5;
omega 0.5;
}
}

[tomf]

angle of attack of 13 degrees => do you expect to have stall or maybe partial separation? If so, you maybe should try to run at a lower angle of attack. It is difficult to get correct stall behavior with RANS.

[giammy92]

No, the flux is attached

[tomf]

Is it attached in the experiment, in the CFD run or anywhere else? Any problems with checkMesh?

You may want to try

    div(phi,k)          bounded Gauss limitedLinear 1;
    div(phi,omega)  bounded Gauss limitedLinear 1;

And while you are trying different schemes:

    div(phi,U)         bounded Gauss GammaV 0.2;

Regards,
Tom

[giammy92]

I haven't try this changes yet, but i can't believe about my successive tests!!! I have changed mixinglenght, with another more large, 5.24e-3. I have still achieved the same Cl og 1.5 about!!! But the worse is that i have put an absurd mixinglenght of 100, and the result is incredibly the same!!! That's crazy!!!! This is no sense,I haven't words to explain this absurdity! Please, help me!!

[giammy92]

My current dat are:

K

dimensions [0 2 -2 0 0 0 0];

internalField uniform 0.0025847;

boundaryField
{
TRAILING_EDGE
{
type fixedValue;
value uniform 1e-12;
}
SUCTION_SIDE
{
type fixedValue;
value uniform 1e-12;
}
FAR_FIELD
{
type turbulentIntensityKineticEnergyInlet;
intensity 0.001;
value uniform 0.0025847;
}
PRESSURE_SIDE
{
type fixedValue;
value uniform 1e-12;
}
frontAndBackPlanes
{
type empty;
}
}

NUT

dimensions [0 2 -1 0 0 0 0];

internalField uniform 0;

boundaryField
{
TRAILING_EDGE
{
type calculated;
value uniform 0;
}
SUCTION_SIDE
{
type calculated;
value uniform 0;
}
FAR_FIELD
{
type calculated;
value uniform 0;
}
PRESSURE_SIDE
{
type calculated;
value uniform 0;
}
frontAndBackPlanes
{
type empty;
}
}

OMEGA

dimensions [0 0 -1 0 0 0 0];

internalField uniform 1769.45;

boundaryField
{
TRAILING_EDGE
{
type omegaWallFunction;
value uniform 1769.45;
}
SUCTION_SIDE
{
type omegaWallFunction;
value uniform 1769.45;
}
FAR_FIELD
{
type turbulentMixingLengthFrequencyInlet;
mixingLength 0.4;
value uniform 1769.45;
}
PRESSURE_SIDE
{
type omegaWallFunction;
value uniform 1769.45;
}
frontAndBack
{
type empty;
}
}

P

dimensions [0 2 -2 0 0 0 0];

internalField uniform 0;

boundaryField
{
TRAILING_EDGE
{
type zeroGradient;
}
SUCTION_SIDE
{
type zeroGradient;
}
FAR_FIELD
{
type freestreamPressure;
}
PRESSURE_SIDE
{
type zeroGradient;
}
frontAndBackPlanes
{
type empty;
}
}

U

imensions [0 1 -1 0 0 0 0];

internalField uniform (40.447 9.338 0); // (41.511*cos13 41.511*sin13)

boundaryField
{
TRAILING_EDGE
{
type fixedValue;
value uniform (0 0 0);
}
SUCTION_SIDE
{
type fixedValue;
value uniform (0 0 0);
}
FAR_FIELD
{
type freestream;
freestreamValue uniform (40.447 9.338 0);
}
PRESSURE_SIDE
{
type fixedValue;
value uniform (0 0 0);
}
frontAndBackPlanes
{
type empty;
}
}

[giammy92]

Do you think that for omega's bc at wall i have to use Menter's recommended wall BC, i. e. omegawall=60*nu/(beta*y^2), with nu=kinematic viscosity at the wall, beta=0.075 and y=normal distance between the first fluid node and the nearest wall ? But how i can calculate y and nu at wall? Is the same of nu calculated with mu/rho?
Or if i want use omegawallfunction i have before implement the code with:
omega[faceCellI] = omegaLog;

i refer to this discussion Why Menter's SST model low-Re issue has not been seriously investigated?