[tareqkh]

Hello All,

This is my first post in this forum, so I would really appreciate any clarification. The question is regarding the use of wall function as well as fixed value at the wall such as airfoil walls. My understanding through the use of the steady state solve simpleFoam is that if we wanted to resolve the boundary layer near the wall for approximate values of y+=1, we would set the boundary conditions at the wall with the following boundaries for kOmegaSST turbulence model;

For the turbulent kinetic energy k;

    
airfoil
    {
        type            fixedValue;
        value           uniform 1e-10;

    }

For the specific dissipation omega;

    
airfoil
    {
        type            fixedValue;
        value           uniform 1e+10;

    }

1e-10 at k means a value close to zero and 1e+10 means close to the infinity. While if our y+ value higher than 40, we would use the following for kOmegaSST;

For the turbulent kinetic energy k;

    
airfoil
    {
        type            kqRWallFunction;
        value           uniform value;

    }

For the specific dissipation omega;

    
airfoil
    {
        type            omegaWallFunction;
        value           uniform value;

    }

Therefore, when we use values of y+ < 10, the boundary condition at the wall for k is close to zero, whereas close to the infinity at the walls for omega. The opposite is true when y+ > 30, means wallfunctions are suitable to use. I was wondering if someone is aware of these boundary conditions and whether the mentioned above is correct or not.

Thanks in advance,

[tomf]

You can also use omegaWallFunction in case of near-wall-treatment.

[tareqkh]

Does omegaWallFunction work for y+ value <10 too?

Have you ever experienced using fixed value instead for y+ <10 (k and omega)?

Is my question addressed incorrectly?

[tomf]

Originally Posted by tareqkh

Does omegaWallFunction work for y+ value <10 too?

Yes it does.

Originally Posted by tareqkh

Have you ever experienced using fixed value instead for y+ <10 (k and omega)?

For k yes, for omega it probably could work, but the omegaWallFunction option gives better results.