adjusting fvSchemes and fvSolution to correct for drag discrepancy
 

I am running a 2D airfoil simulation of a NACA23012 section using simpleFoam as a solver.

The CL vs alpha seems to be in the ballpark with experimental results, but the drag is way too high. I understand that this is a common problem with turbulence model simulations. Right now I am using the native OpenFOAM SpalartAllmaras turbulence model with the default parameters.

After browsing through several posts on the subject, I am led to believe that the adjustments to the drag solution can be made through the fvScheme and fvSolution files. However, I have no idea how to tweak them. Is there an online tutorial anywhere that can point me to a solution? If not, what is the best way to proceed in this situation?

Hi,
did you solve the problem?

im also stuck here :(

any chance for you all to share a minimal example or the full case, so that we can also try to test what is going on?

Files in the 0 folder
 

/*--------------------------------*- C++ -*----------------------------------*\
========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration | Website: https://openfoam.org
\\ / A nd | Version: 8
\\/ M anipulation |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class volVectorField;
object U;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

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

internalField uniform (0 0 0);

boundaryField
{
INLET
{
type fixedValue;
value (50 0 0);
}

OUTLET
{
type freestreamVelocity;
freestreamValue $internalField;
}

AIRFOIL
{
type noSlip;
}

TOP
{
type symmetry;
}

BOTTOM
{
type symmetry;
}

frontAndBack
{
type empty;
}
}

// ************************************************** *********************** //

/*--------------------------------*- C++ -*----------------------------------*\
========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration | Website: https://openfoam.org
\\ / A nd | Version: 8
\\/ M anipulation |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class volScalarField;
object p;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

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

internalField uniform 82714.29;

boundaryField
{
INLET
{
type zeroGradient;

}

OUTLET
{
type freestreamPressure;
freestreamValue $internalField;
}

AIRFOIL
{
type zeroGradient;
}

TOP
{
type symmetry;
}

BOTTOM
{
type symmetry;
}
frontAndBack
{
type empty;
}
}

// ************************************************** *********************** //


/*--------------------------------*- C++ -*----------------------------------*\
========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration | Website: https://openfoam.org
\\ / A nd | Version: 8
\\/ M anipulation |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class volScalarField;
object nut;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

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

internalField uniform 0.14;

boundaryField
{
INLET
{
type freestream;
freestreamValue uniform 0.14;
}

OUTLET
{
type freestream;
freestreamValue uniform 0.14;
}

AIRFOIL
{
type nutUSpaldingWallFunction;
value uniform 0;
}

TOP
{
type symmetry;
}

BOTTOM
{
type symmetry;
}

frontAndBack
{
type empty;
}
}

// ************************************************** *********************** //

/*--------------------------------*- C++ -*----------------------------------*\
========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration | Website: https://openfoam.org
\\ / A nd | Version: 8
\\/ M anipulation |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class volScalarField;
object nuTilda;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

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

internalField uniform 0.14;

boundaryField
{
INLET
{
type freestream;
freestreamValue uniform 0.14;
}

OUTLET
{
type freestream;
freestreamValue uniform 0.14;
}

AIRFOIL
{
type fixedValue;
value uniform 0;
}

TOP
{
type symmetry;
}

BOTTOM
{
type symmetry;
}

frontAndBack
{
type empty;
}
}

// ************************************************** *********************** //

Files in the system folder
 

/*--------------------------------*- C++ -*----------------------------------*\
========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration | Website: https://openfoam.org
\\ / A nd | Version: 8
\\/ M anipulation |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
location "system";
object controlDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

application simpleFoam;

startFrom startTime;

startTime 0;

stopAt endTime;

endTime 200000;

deltaT 1;

writeControl timeStep;

writeInterval 5;

purgeWrite 0;

writeFormat ascii;

writePrecision 6;

writeCompression off;

timeFormat general;

timePrecision 6;

runTimeModifiable true;

functions
{
forces
{
type forceCoeffs;
libs ("libforces.so");
writeControl timeStep;
writeInterval 1;

patches
(
AIRFOIL
);

log true;
rho rhoInf;
rhoInf 1;
CofR (0 0 0);
liftDir (0 1 0);
dragDir (1 0 0);
pitchAxis (0 0 1);
magUInf 50;
lRef 1;
Aref 1;
}
}

// ************************************************** *********************** //

/*--------------------------------*- C++ -*----------------------------------*\
========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration | Website: https://openfoam.org
\\ / A nd | Version: 8
\\/ M anipulation |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
location "system";
object fvSolution;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

solvers
{
p
{
solver GAMG;
tolerance 1e-06;
relTol 0.1;
smoother GaussSeidel;
}

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

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

SIMPLE
{
nNonOrthogonalCorrectors 0;

residualControl
{
p 1e-5;
U 1e-5;
nuTilda 1e-5;
}
}

relaxationFactors
{
fields
{
p 0.3;
}
equations
{
U 0.7;
nuTilda 0.7;
}
}


// ************************************************** *********************** //


/*--------------------------------*- C++ -*----------------------------------*\
========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration | Website: https://openfoam.org
\\ / A nd | Version: 8
\\/ M anipulation |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
location "system";
object fvSchemes;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

ddtSchemes
{
default steadyState;
}

gradSchemes
{
default Gauss linear;
}

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

laplacianSchemes
{
default Gauss linear corrected;
}

interpolationSchemes
{
default linear;
}

snGradSchemes
{
default corrected;
}

wallDist
{
method meshWave;
}


// ************************************************** *********************** //

no, I meant by a minimal example that could be downloadable and executable easily and effortlessly. thanks.