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Drag is too much high

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Old   May 23, 2020, 12:24
Default Drag is too much high
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burak
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Hello ,



I am analysing 2D NACA0012 airfoil . My solver is pimpleFoam . Reynold number is 1500000 and yplus value is 1 ( probably this can be wrong). Turbulence model is k-omega SST but also tried other models (spalartallmaras and k-epsilon) .My mesh type is hybrid triangle mesh I also tried c-mesh. Unfortunateley , I always get high drag coefficient value in every different attemp at 0 degree angle of attack. Experimental result is 0.01 but I always get the value of 0.1. When I increase my yplus value , I get faster solution but there is no change in drag coefficient as always. What are your advices ? I am amateur in openfoam , maybe there is a huge fault but I didnt find yet.



these are my system files ;


FoamFile
{
version 2.0;
format ascii;
class dictionary;
location "system";
object fvSchemes;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

ddtSchemes
{
default CrankNicolson 0.5;
}

gradSchemes
{
default Gauss linear;
grad(U) cellLimited Gauss linear 1;
}

divSchemes
{
default none;
div(phi,U) Gauss limitedLinearV 1;
div(phi,k) Gauss limitedLinear 1;
div(phi,omega) Gauss limitedLinear 1;
div((nuEff*dev2(T(grad(U))))) Gauss linear;
}

laplacianSchemes
{
default Gauss linear corrected 0.5;
}

interpolationSchemes
{
default linear;
}

snGradSchemes
{
default corrected;
}

wallDist
{
method meshWave;
}





------------------------------------


solvers
{
"pcorr.*"
{
solver GAMG;
tolerance 0.02;
relTol 0;
smoother GaussSeidel;

}

p
{
$pcorr;
tolerance 1e-7;
relTol 0.01;
}

pFinal
{
$p;
tolerance 1e-7;
relTol 0;
}

"(U|k|omega)"
{
solver smoothSolver;
smoother symGaussSeidel;
tolerance 1e-06;
relTol 0.1;
}

"(U|k|omega)Final"
{
$U;
tolerance 1e-06;
relTol 0;
}

cellDisplacement
{
solver GAMG;
tolerance 1e-5;
relTol 0;
smoother GaussSeidel;
}
}

PIMPLE
{
nCorrectors 2;
nNonOrthogonalCorrectors 1;
nOuterCorrectors 1;
pMinFactor 0.1;
pMaxFactor 2;
pRefCell 0;
pRefValue 0;
}

relaxationFactors
{
fields
{
p 0.3;

}
equations
{
"(U|k|omega)" 0.7;
"(U|k|omega)Final" 1.0;
}
}

cache
{
grad(U);
}



----------------------------------------------



application pimpleDyMFoam;

startFrom latestTime;

startTime 0;

stopAt endTime;

endTime 0.15;

deltaT 2e-5;

writeControl adjustableRunTime;

writeInterval 0.001;

purgeWrite 0;

writeFormat ascii;

writePrecision 8;

writeCompression off;

timeFormat general;

timePrecision 6;

runTimeModifiable true;

maxCo 0.9;

functions
{
sixDoFRigidBodyState
{
type sixDoFRigidBodyState;
libs ("libsixDoFRigidBodyState.so");
angleFormat degrees;
}
}

functions
{
forces
{
type forces;
functionObjectLibs ("libforces.so");
patches (airfoil);
rho rhoInf;
rhoInf 1000;
CofR ( 0 0 0 );
magUInf 1.5;
}
forceCoeffs
{
type forceCoeffs;
functionObjectLibs ("libforces.so");
patches (airfoil);
rho rhoInf;
rhoInf 1000;
liftDir (0 1 0);
dragDir (1 0 0);
pitchAxis (0 0 1);
magUInf 1.5;
lRef 1;
Aref 1;
CofR ( 0 0 0 );
}

}
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