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-   -   Does RSM use wall function? (http://www.cfd-online.com/Forums/main/8773-does-rsm-use-wall-function.html)

Sam March 2, 2005 02:09

Does RSM use wall function?
 
Hi,

Just have a quick question for LRR or SSG Reynolds stress models. Does these models use wall function to model the near wall flow? If so, we will need to consider the Yplus limit, right? If not, How can the near wall flow be modelled if RSM is used. Thanks for any comments here.

Hrvoje Jasak March 2, 2005 04:37

Re: Does RSM use wall function?
 
Yes, they need wall functions, with all the limitations that brings in. There are also some low-Re Reynolds stress models in literature, but I have never implemented one myself. Rumour is that they are very unstable/dificult to solve and don't give you the benefit you expect (but my news may be a generation behind the "latest and greatest").

Hrv

Sam March 2, 2005 19:31

Re: Does RSM use wall function?
 
Hi Hrvoje,

Thanks for your comment here. I recently run a case using a pretty fine mesh near the wall. No problem to converge if k-w/k-e model is used. When it comes to RSM, it just doesn't want to converge properly. I guess RSM is more sensitive to the Y+ value in this case ( I say so because when I increase the wall distance from first node, it does improve the convergence). Just wonder why.....

JC March 2, 2005 22:53

Re: Does RSM use wall function?
 
Hi,

I am not a turbulence modeling expert; however, a google on reynolds stresses and near wall showed the following:

It probably is what you want, and it comes from one of the big school in turbulence modeling:

http://personalpages.umist.ac.uk/sta...r/turbcfd2.pdf

Good luck, and let us know how it goes

JC..

Sam March 3, 2005 00:58

Re: Does RSM use wall function?
 
Hi Jc,

Thanks for the link. It's really handy. :)

I think there's some low-Re kw-RSM models available as well.... I'll try it out later...


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