CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Main CFD Forum

Smagorinsky model and Sij terms

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Display Modes
Old   December 6, 2004, 12:30
Default Smagorinsky model and Sij terms
  #1
James
Guest
 
Posts: n/a
I'm currently updating a code that uses the Smagorinsky model as its sgs model. At present the code calculates Sij in the form:

Sij**2 = S11**2 + S22**2 + S33**2 + 2S12**2 + 2S13**2 + 2S23**2

in order to calculate the eddiy viscostiy.

Now, as the |S| term is SQRT(2SijSij), is is clear that the Sij**2 shown above and SijSij calculated normally do not commute, so which one should I use? Is the above implmentation wrong?

Thanks,

James
  Reply With Quote

Old   December 6, 2004, 15:32
Default Re: Smagorinsky model and Sij terms
  #2
agg
Guest
 
Posts: n/a
I think the above implementation is correct. Sij**2 = Sij:Sij = Sij*Sji
  Reply With Quote

Old   December 6, 2004, 20:24
Default Re: Smagorinsky model and Sij terms
  #3
Adrin Gharakhani
Guest
 
Posts: n/a
It all depends on the definitions of S11, S22, S12, etc. in the code. The equation you have written is neither wrong nor right; you have simply not provided sufficient information.

This is a two minute exercise in algebra. You know Sij = {ui,j + uj,i}/2 and Sij*Sij simply uses the repeated index notation. You can then verify by yourself whether your code is right or wrong

Adrin Gharakhani
  Reply With Quote

Old   December 7, 2004, 11:20
Default Re: Smagorinsky model and Sij terms
  #4
James
Guest
 
Posts: n/a
The current code in indeed correct. I should try to remember how tensor notation works!
  Reply With Quote

Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Modified k-e turbulence model UDF - help! Travis FLUENT 5 January 20, 2014 08:34
Implementing new turbulence model sven OpenFOAM 13 October 12, 2009 13:18
Reynolds transport, turbulence model, etc Beginner Main CFD Forum 1 January 7, 2009 06:36
Implementation of Germano-Lilly model in LES Andrew McMullan Main CFD Forum 0 November 27, 2003 10:50


All times are GMT -4. The time now is 16:51.