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August 5, 2018, 09:59
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VAWT Sliding Mesh - Negative Torque
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#1 |
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New Member
Tommaso Pascon
Join Date: Mar 2016
Posts: 18
Rep Power: 10  |
Hello everyone,
I'm trying to simulate a 2D VAWT based on the following paper: http://docsdrive.com/pdfs/ansinet/jest/2011/302-312.pdf Turbine diameter: 8m NACA2415, chord length 1m; Vfree = 4 m/s; TSR = 1.5 = omega Turbulence model RNG Kepsilon with wall function. I see that I have similar values for the highest torque (around 80Nm) while I also get negative values in some regions. Since I'm noticing this as a common behavior in all my simulations, what could be the cause of this negative torque?  If someone can give me some tips would be much appreciated. U Code:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.3.0 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ 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
{
sides
{
type empty;
}
blades
{
type movingWallVelocity;
value uniform (0 0 0);
}
inlet
{
type fixedValue;
value uniform (4 0 0);
}
bottom
{
type symmetryPlane;
}
outlet
{
type zeroGradient;
}
top
{
type symmetryPlane;
}
#include "include/ami"
}
// ************************************************************************* //
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.3.0 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class volScalarField;
object p;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
dimensions [0 2 -2 0 0 0 0];
internalField uniform 0;
boundaryField
{
sides
{
type empty;
}
blades
{
type zeroGradient;
}
inlet
{
type zeroGradient;
}
bottom
{
type symmetryPlane;
}
outlet
{
type fixedValue;
value uniform 0;
}
top
{
type symmetryPlane;
}
#include "include/ami"
}
// ************************************************************************* //
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.3.0 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class volScalarField;
location "0";
object k;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
dimensions [0 2 -2 0 0 0 0];
internalField uniform 0.0615;
boundaryField
{
sides
{
type empty;
}
blades
{
type kqRWallFunction;
value uniform 0.0615;
}
inlet
{
type fixedValue;
value uniform 0.0615;
}
bottom
{
type symmetryPlane;
}
outlet
{
type zeroGradient;
}
top
{
type symmetryPlane;
}
#include "include/ami"
}
// ************************************************************************* //
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.3.0 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class volScalarField;
location "0";
object epsilon;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
dimensions [0 2 -3 0 0 0 0];
internalField uniform 0.036;
boundaryField
{
sides
{
type empty;
}
blades
{
type epsilonWallFunction;
value uniform 0.036;
}
inlet
{
type fixedValue;
value uniform 0.036;
}
bottom
{
type symmetryPlane;
}
outlet
{
type zeroGradient;
}
top
{
type symmetryPlane;
}
#include "include/ami"
}
// ************************************************************************* //
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.3.0 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class volScalarField;
location "0";
object nut;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
dimensions [0 2 -1 0 0 0 0];
internalField uniform 0;
boundaryField
{
sides
{
type empty;
}
blades
{
type nutkWallFunction;
value uniform 0;
}
inlet
{
type calculated;
value uniform 0;
}
bottom
{
type symmetryPlane;
}
outlet
{
type calculated;
value uniform 0;
}
top
{
type symmetryPlane;
}
#include "include/ami"
}
// ************************************************************************* //
Code:
//c++
ami00 { type cyclicAMI;value $internalField; }
ami01 { type cyclicAMI;value $internalField; }
//ami10 { type cyclicAMI;value $internalField; }
//ami11 { type cyclicAMI;value $internalField; }
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.4.0 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
location "constant";
object dynamicMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
dynamicFvMesh dynamicMotionSolverFvMesh;
motionSolver solidBody;
cellZone rotor;
solidBodyMotionFunction rotatingMotion;
origin (0 0 0);
axis (0 0 1);
omega 1.5; //14.96 rad/s
// ************************************************************************* //
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 1.5 |
| \\ / A nd | Web: http://www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object fvSolution;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
myPTolerance 1e-4;
myTolerance 1e-10;
myRelaxation 1;
solvers
{
"(p|pFinal|pcorr)"
{
solver GAMG;
mergeLevels 1;
smoother GaussSeidel;
agglomerator faceAreaPair;
nCellsInCoarsestLevel 1500;
tolerance $myPTolerance;
relTol 0;
}
"(U|UFinal|k|kFinal|omega|omegaFinal|epsilon|epsilonFinal|nuTilda|nuTildaFinal)"//epsilon|R
{
solver smoothSolver;//PBiCG
smoother GaussSeidel;//preconditioner DILU;
tolerance $myTolerance;
relTol 0;
}
}
PIMPLE
{
correctPhi no;
nOuterCorrectors 1;
nCorrectors 3;
nNonOrthogonalCorrectors 1;
pRefCell 0;
pRefValue 0;
}
relaxationFactors
{
fields
{
p $myRelaxation;
}
equations
{
k $myRelaxation;
U $myRelaxation;
omega $myRelaxation;
epsilon $myRelaxation;
nuTilda $myRelaxation;
}
}
// ************************************************************************* //
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.1.1 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object fvSchemes;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
ddtSchemes
{
default Euler;
}
gradSchemes
{
default Gauss linear;
grad(p) Gauss linear;
grad(U) Gauss linear;
}
divSchemes
{
default none;//Gauss linearUpwind leastSquares;
//div(phi,U) Gauss linearUpwind grad(U);
div(phi,U) Gauss upwind;
//div(phi,U) Gauss linearUpwind leastSquares;//upwind;//linearUpwind grad(U);
div(phi,nuTilda) Gauss upwind;//linearUpwind leastSquares;//upwind;//limitedLinear 1;
div(phi,k) Gauss upwind;//linearUpwind leastSquares;//upwind;//limitedLinear 1;
div(phi,omega) Gauss upwind;//linearUpwind leastSquares;//upwind;//limitedLinear 1;
div(phi,epsilon) Gauss upwind;//linearUpwind leastSquares;//upwind;
div((nuEff*dev2(T(grad(U))))) Gauss linear;
}
laplacianSchemes
{
default Gauss linear limited 1;
}
interpolationSchemes
{
default linear;
}
snGradSchemes
{
default corrected;
}
fluxRequired
{
default no;
pcorr;
p;
}
// ************************************************************************* //
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.4.0 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
location "system";
object controlDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
applicationClass pimpleDyMFoam;
startFrom latestTime;
endTime 83;
stopAt endTime;
deltaT 1;
writeControl adjustableRunTime;
writeInterval 5;
cycleWrite 0;
writeFormat ascii;
writePrecision 6;
writeCompression uncompressed;
timeFormat general;
timePrecision 6;
runTimeModifiable yes;
adjustTimeStep yes;
maxCo 1;
maxDeltaT 0.023;
functions
{
blades
{
patches (blades);
CofR (0 0 0); //Origin for moment calculations
outputControl timeStep;outputInterval 2;
type forces;functionObjectLibs ("libforces.so");pName p;UName U;rho rhoInf;rhoInf 1.225;log true;
}
forceCoeffs
{
type forceCoeffs;
functionObjectLibs ( "libforces.so" );
outputControl timeStep;
outputInterval 2;
patches ( "blades" );
pName p;
UName U;
rho rhoInf;
log true;
liftDir (0 1 0);
dragDir (1 0 0);
CofR (0 0 0);
pitchAxis (0 0 1);
magUInf 4;
rhoInf 1.225;
lRef 4;
Aref 8;
}
// ************************************************************************* //
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