[spalartallmaras]

Hallo,

I simulate channel flow for Re_tau=395 for long time, but I have always really large <u'u'> near the wall. I simulate with pimpleFoam.
Inlet, Outlet, left and right are cyclic and walls are wall.

My setup is,

1. nu=2,53e-03 (so 1/nu=395)
2. bulk velocity is about 22-23 m/s (patchMeanVelocityForce on inlet), so wallShearStressMean and u_tau are also about 1. Density is supposed to be 1 kg/m^3.
3. turbulence model is WALE-Modell
4. because Re_bulk is low, I use createBoxTurb before the pimpleFoam.
5. Mesh is really coarse, 32*32*32, because I want to make the mesh fine later.
6. After the flow is turbulent enough, I switch on the fieldAverage1.

but I have always <u'u'> about 20-22 m^2/s^2 near the wall. But it should be about 7-8 m^2/s^2 from Reference.

What will be the problem?

[spalartallmaras]

Nobody has idea?

[Santiago]

Originally Posted by spalartallmaras

Hallo,

I simulate channel flow for Re_tau=395 for long time, but I have always really large <u'u'> near the wall. I simulate with pimpleFoam.
Inlet, Outlet, left and right are cyclic and walls are wall.

My setup is,

1. nu=2,53e-03 (so 1/nu=395)
2. bulk velocity is about 22-23 m/s (patchMeanVelocityForce on inlet), so wallShearStressMean and u_tau are also about 1. Density is supposed to be 1 kg/m^3.
3. turbulence model is WALE-Modell
4. because Re_bulk is low, I use createBoxTurb before the pimpleFoam.
5. Mesh is really coarse, 32*32*32, because I want to make the mesh fine later.
6. After the flow is turbulent enough, I switch on the fieldAverage1.

but I have always <u'u'> about 20-22 m^2/s^2 near the wall. But it should be about 7-8 m^2/s^2 from Reference.

What will be the problem?

Which schemes are you using? time step?

[spalartallmaras]

Originally Posted by Santiago

Which schemes are you using? time step?

Thank you for your answer, I will post it in 5-6h.

Time step is maxCo = 0.99.

[spalartallmaras]

Here I post my fvSchemes file,

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

ddtSchemes
{
    default         backward;
}

gradSchemes
{
    default         Gauss linear;
}

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

laplacianSchemes
{
    default         Gauss linear corrected;
}

interpolationSchemes
{
    default         linear;
}

snGradSchemes
{
    default         corrected;
}

wallDist
{
    method meshWave;
}



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

[Severus]

Hello,
This issue has been discussed and solved in another post.
I am adding the link below so that it could be useful for others with the same problem.
channel flow, too large reynolds stress <u'u'> near the wall

Thanks