low reynolds k omega / wall functions
 

Hi,


I make my first steps with low-Reynolds models for heat transfer analysis.


When I understand the new wall function approach in OF 1.6. correctly, I “simply” can switch off the wall functions e.g. by using “calculated” in the nut-file and some reasonable bcs for omega and k at the walls. I build some test cases with grids of y+ below “1” and used fixed values for k (I used very low non-zero values) and zero gradient for omega. Does this make sense? But the convergence is quite poor and the results (e.g. when I estimate wallShear stresses from different models) differ strongly. Any hints or recommendations?
I also read that Fluent uses a low Reynolds correction for the k-omega model. Did anybody implement something like this in OF or compared the effect?




Thanks in advance


Stawrogin

Hey Stawrogin,

" fixed values for k (I used very low non-zero values) and zero gradient for omega. Does this make sense?"

Fixed values for k which are non-zero but low are good but zero gradient for omega does not make sense.
Have a look at the post

http://www.cfd-online.com/Forums/ope...tml#post296705