[tilasoldo]

Hello Foamers,

I want to calculate y+ = y u* / nu and u+ = u / u* with functionObjects in Openfoam.

I managed to retrieve y as a wallDist, nu from the turbulence model and U. I also get u* as a volScalarField, defined only on the wall patch (zero elsewhere), with another functionObject.

Now in order to calculate u+ and y+ in the whole field, I need to use for every cell the value of u* on the closest face on the boundary. I don t have any clue on how to do that...

You will find attached the code of my 3 functionObjects for u*, y+ and u+, which use for now the average of u* on the patch.


Any help would be greatly appreciated.
X. Lamboley


turbulence_functionObjects.tar.gz

[tilasoldo]

After some investigation I found a solution by looping over the mesh points. You will find attached the updated code.

The method is to loop over the mesh points, then looping over the surface faces. I keep the nearest x on the surface for each mesh point, and assign its wallShearStress.

This works well, if the point are sufficiently aligned along the vertical.

Cheers,
X. Lamboley

[jherb]

Thank you for sharing the code. Could you please also give an example, how to use this in the controlDict. Or how do you else use function objects?

[calf.Z]

I am also in u+ calculation. Could you give more explanation？ Thanks.