CFD Online Discussion Forums - High-Re / Boundary Layers

Hi Foamers,
I'm trying to solve directly the boundary layers for an High-Re flow around a submarine.
I'm doing steadyState simulation with the kOmegaSST model (this model gave me the best results with the wallFunctions for a yPlus=10 mesh, I attached the checkMesh)

Since I didn't get any results with my submarine and every simulation take time to solve or at least to give an indication about the convergence or not of the simulation, I create a simple sphere model to test different configuration and get faster results. I'm not actually looking for accuracy but for the convergence in a first time.

I made a Re similarity and set the model. First, is that ok ?

I already try all the possibility for k,omega and nut with the following schemes :

Code:

gradSchemes

{

    default         Gauss linear;

    grad(p)         Gauss linear;

    grad(U)         Gauss linear;

}



divSchemes

{

    default         none;

    div(phi,U)      Gauss upwind;

    div(phi,k)      Gauss upwind;

    div(phi,omega)  Gauss upwind;

    div((nuEff*dev(grad(U).T()))) Gauss linear;

}



laplacianSchemes

{

    default         Gauss linear corrected;



}

And all the simulation crashed after a few time step.
I'm curently running the same things with :

Quote:

gradSchemes
{
default Gauss linear;
grad(p) Gauss linear;
grad(U) Gauss linear;

}

divSchemes
{
default none;
div(phi,U) Gauss linearUpwindV Gauss linear;
div(phi,k) Gauss linearUpwind Gauss linear;
div(phi,omega) Gauss linearUpwind Gauss linear;
div((nuEff*dev(grad(U).T()))) Gauss linear;
}

laplacianSchemes
{
default Gauss linear corrected;
}

I'll continue exploring different scheme settings after.

Do you some advice about the better schemes to solve the boundary layers for High-Re flows ?
And about the better settings for k, omega and nut ?

For the moment I decided to keep the same fvSolution settings

Quote:

solvers
{
p
{
solver GAMG;
tolerance 1e-12;
relTol 0.05;
smoother GaussSeidel;
nPreSweeps 0;
nPostSweeps 2;
cacheAgglomeration true;
nCellsInCoarsestLevel 10;
agglomerator faceAreaPair;
mergeLevels 1;
};

U
{
solver smoothSolver;
smoother GaussSeidel;
tolerance 1e-10;
relTol 0.1;
nSweeps 1;
};

k
{
solver smoothSolver;
smoother GaussSeidel;
tolerance 1e-10;
relTol 0.1;
nSweeps 1;
};

omega
{
solver smoothSolver;
smoother GaussSeidel;
tolerance 1e-10;
relTol 0.1;
nSweeps 1;
};
}

SIMPLE
{
nNonOrthogonalCorrectors 0;
}

relaxationFactors
{
p 0.3;
U 0.7;
k 0.7;
omega 0.7;
}

But playing with the URF is option which I have to explore.

If you have some advice for that too it will help me ?

Can it help me to solve it with a transient model ?

If you need more details about the model please ask me.

Hope someone can help me :)