Velocity wall function
 

Hi everyone!

Hope you going well.

I was trying to implement a BC as a wall function for U like one shown in the picture.

I'm was trying to find something similar but I found nothing so far. Is someone here able to guide me with something, tutorial, BC template for U.

Or, is maybe better to implement a shear/gradient at the wall?

Thanks and best Regards,

https://www.openfoam.com/documentati...lFunction.html


This is quite close to what you look for I think.



I've never seen a wall function for U which implements the velocity at the wall directly. You usually compute the wall shear stress which is consistent with your assumed velocity profile. In this case a logarithmic velocity distribution over the cell adjacent to the wall


Best


Michael

Also, have a look at https://www.openfoam.com/documentati...lFunction.html , particularly the citations where


Eqs. 6-7 in
PJ Richards and RP Hoxey. Appropriate boundary conditions for computational wind engineering models using the k-ε turbulence model. In Computational Wind Engineering 1, pages 145–153. Elsevier, 1993.

were mentioned for the implementation.

Hope it helps.

I use 'nutkAtmRoughWallFunction'' from openfoam v1906 and the results on U isn't what it should compare to the analytics solution close to the wall. Also, I noticed that the one suggested in openfoam v2006 doesn't seams exactly the same.

So, I assume that I still need to set U at the wall U = (0 0 0)?

Do you have an idea or rational explanation why the author in this case present this that way (Uw) instead of presenting it with 'nutw' or it's probably based on the authors preferences?

Thank you for replying!

It's work! I got the right results on the velocity.

Thank you again!