[val1560]

Hi foamers,

Context: I am currently running 2D simulations with interFoam (v2406), URANS with a k-omega SST turbulence model.
A water jet is impacting a 35-blade runner, which is rotating in the air.

My problem: the fluid fraction in the first cells of my boundary layer is not reaching the expected alpha.water = 1. This happens in regions where the blade is completely surrounded by water and where there should be no air close to the blade.
This implies a pressure gap between the first and the following cells of the layers around the blades. The pressure gap is about 10% of the average pressure around the blades in this region full of water.

The turbine torque is directly related to the pressure field around the blades and I am thus worried that the pressure gap observed may affect the performance prediction.

I have tried several types of meshes and different aspect ratios:
- Ansys meshing triangles (named tri_, aspect ratio of max 60) and tri_thinner_, aspect ratio of max 30);
- Ansys meshing quadrilaterals (named quad_, aspect ratio of max 60);
- And snappyHexMesh with boundary layer (named snappyHexMesh_, aspect ratio of max 30).

with no improvement on this problem. (all checkMesh are good)

If you have any idea that may correct or help understand this problem, I would be interested.
Here are some snapshots (for all meshes, alpha.water=aw, pressure on the top and the bottom of the blade).

Files here: https://filesender.renater.fr/?s=dow...a-aec00f12b131




Thank you.

Valentin

[VRN]

Hello val1560,

May I ask what advection schemes are being used in your simulations? Do you use the default interface-compression method or any interface reconstruction schemes?

[val1560]

Originally Posted by VRN

Hello val1560,

May I ask what advection schemes are being used in your simulations? Do you use the default interface-compression method or any interface reconstruction schemes?

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


Hello,


Here are my fvSchemes and fvSolution files.


thank you for your interest !









/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: v2312 |
| \\ / A nd | Website: www.openfoam.com |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object fvSolution;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *



solvers
{

p_rgh
{
solver PCG;
preconditioner DIC;
tolerance 1e-4;
relTol 0.01;
minIter 1;
maxIter 200;
}

p_rghFinal
{
solver PCG;
preconditioner DIC;
tolerance 1e-06;
relTol 0;
maxIter 50;
}

// ----------------------------------------------------- //

pcorr
{
solver PCG;
preconditioner DIC;
tolerance 1e-04;
relTol 0;
maxIter 200;
}
pcorrFinal
{
solver PCG;
preconditioner DIC;
tolerance 1e-06;
relTol 0;
maxIter 50;
}

// ----------------------------------------------------- //

"alpha.water.*"
{
solver smoothSolver;
smoother symGaussSeidel;
tolerance 1e-8;
relTol 0;

nAlphaCorr 10;
nAlphaSubCycles 1;
cAlpha 0.9;

MULESCorr yes;
nLimiterIter 10;
alphaApplyPrevCorr no;
}

// ----------------------------------------------------- //

"(U|k|omega)"
{
solver smoothSolver;
smoother GaussSeidel;
tolerance 1e-6;
relTol 0.1;
nSweeps 1;
maxIter 500 ;
}

"(U|k|omega)Final"
{
solver smoothSolver;
smoother GaussSeidel;
tolerance 1e-6;
relTol 0;
nSweeps 1;
}
}

// ----------------------------------------------------- //

PIMPLE
{
nNonOrthogonalCorrectors 2;
nOuterCorrectors 10;
nCorrectors 2;
momentumPredictor no;

correctPhi yes;
moveMeshOuterCorrectors yes;
checkMeshCourantNo yes;

residualControl
{
p_rgh
{
tolerance 1e-4;
relTol 0.000001;
}
}

}

relaxationFactors
{
equations
{
".*" 1;
}
}


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



















/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: v2212 |
| \\ / A nd | Website: www.openfoam.com |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object fvSchemes;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //


ddtSchemes
{
default CrankNicolson 0.7; //0.9;
}

gradSchemes
{
default cellLimited Gauss linear 1 ; //leastSquares 1;
}

divSchemes
{
div(rhoPhi,U) Gauss linearUpwind grad(U);
div(phi,alpha) Gauss upwind;
div(phirb,alpha) Gauss upwind;
div(phid1,p_rgh) Gauss upwind;
div(phid2,p_rgh) Gauss upwind;
div(rhoPhi,T) Gauss linearUpwind unlimited;
div(rhoPhi,K) Gauss upwind;
div(phi,k) Gauss upwind;
div(phi,omega) Gauss upwind;
div(((rho*nuEff)*dev2(T(grad(U))))) Gauss linear;
}

laplacianSchemes
{
default Gauss linear limited corrected 0.5;
}

interpolationSchemes
{
default linear;
}

snGradSchemes
{
default limited corrected 0.5;
}
/*
fluxRequired
{
default no;
pcorr ;
p ;
p_rgh ;
alpha.water;
}
*/

wallDist
{
method meshWave;
}

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

[val1560]

Hello,


here are my fvSchemes and fvSolution files.


Thank you for your interest.


Valentin


/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: v2212 |
| \\ / A nd | Website: www.openfoam.com |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object fvSchemes;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *


ddtSchemes
{
default CrankNicolson 0.7; //0.9;
}

gradSchemes
{
default cellLimited Gauss linear 1 ;
}

divSchemes
{
div(rhoPhi,U) Gauss linearUpwind grad(U);
div(phi,alpha) Gauss interfaceCompression vanLeer 1; // Gauss vanLeer;
div(phirb,alpha) Gauss linear;
div(phid1,p_rgh) Gauss upwind;
div(phid2,p_rgh) Gauss upwind;
div(rhoPhi,T) Gauss linearUpwind unlimited;
div(rhoPhi,K) Gauss upwind;
div(phi,k) Gauss upwind;
div(phi,omega) Gauss upwind;
div(((rho*nuEff)*dev2(T(grad(U))))) Gauss linear;
}

laplacianSchemes
{
default Gauss linear limited corrected 0.5;
}

interpolationSchemes
{
default linear;
}

snGradSchemes
{
default limited corrected 0.5;
}

wallDist
{
method meshWave;
}

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


and







/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: v2312 |
| \\ / A nd | Website: www.openfoam.com |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object fvSolution;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //


// ----------------------------------------------------- //
// SO9__tol4
// ----------------------------------------------------- //

solvers
{

p_rgh
{
solver PCG;
preconditioner DIC;
tolerance 1e-4;
relTol 0.01;
minIter 1;
maxIter 200;
}

p_rghFinal
{
solver PCG;
preconditioner DIC;
tolerance 1e-06;
relTol 0;
maxIter 50;
}

// ----------------------------------------------------- //

pcorr
{
solver PCG;
preconditioner DIC;
tolerance 1e-04;
relTol 0;
maxIter 200;
}
pcorrFinal
{
solver PCG;
preconditioner DIC;
tolerance 1e-06;
relTol 0;
maxIter 50;
}

// ----------------------------------------------------- //

"alpha.water.*"
{
solver smoothSolver;
smoother symGaussSeidel;
tolerance 1e-8;
relTol 0;

nAlphaCorr 10;//5;
nAlphaSubCycles 1;
cAlpha 0.9;//1;

MULESCorr yes;
nLimiterIter 10; //5;
alphaApplyPrevCorr no;
}

// ----------------------------------------------------- //

"(U|k|omega)"
{
solver smoothSolver;
smoother GaussSeidel;
tolerance 1e-6;
relTol 0.01;
nSweeps 1;
minIter 1;
maxIter 500 ;
}

"(U|k|omega)Final"
{
solver smoothSolver;
smoother GaussSeidel;
tolerance 1e-6;
relTol 0;
minIter 1;
nSweeps 1;
}
}


// ----------------------------------------------------- //

PIMPLE
{
nNonOrthogonalCorrectors 2;
nOuterCorrectors 10;
nCorrectors 2;
momentumPredictor no;

turbOnFinalIterOnly false;

correctPhi yes;
moveMeshOuterCorrectors yes;
checkMeshCourantNo yes;

residualControl
{
p_rgh
{
tolerance 1e-4;
relTol 0.000001;
}
}

}

relaxationFactors
{
equations
{
".*" 1;
}
}


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