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

What wall function for y+ below 30?

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

Reply
 
LinkBack Thread Tools Display Modes
Old   November 1, 2006, 11:50
Default What wall function for y+ below 30?
  #1
Ralf Schmidt
Guest
 
Posts: n/a
Hi!

I have a grid, where the yplus values are close to 30 (20-50). Now, the question is, what wall function will be appropiate? the standard wall function is good for 30 < yplus < 300 and for the other wall functions, yplus has to be below 5.

So what is the right choice? I don't want to modell the whole geometry again, because of 3 reasons:

- first: it was a hell lot of work to generate that geometry,

- second: to increase yplus, the gab between two walls is to small and

- third: to lower yplus, to many cells will result.

Any idea?

Ralf
  Reply With Quote

Old   November 2, 2006, 03:50
Default Re: What wall function for y+ below 30?
  #2
Razvan
Guest
 
Posts: n/a
Standard wall functions are not the only ones working with 30 < y+ < 300. Non-equilibrium wall functions are a derivative of standard wall functions, sensitized to adverse pressure gradient. They are absolutely OK to use when APG is medium (for high APG they are no longer appropriate, you will need y+=1 mesh and low-Re model). I used these non-equilibrium functions on airfoils like Onera M6 and on transonic compressor blades like NASA Rotor 37 with y+(medium)=33-40, and the results were excellent.

y+ values between 20 and 50 are quite OK, if the 20 values are only on small portion of the wall or in not so important areas.

Razvan
  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
Compile problem ivanyao OpenFOAM Running, Solving & CFD 1 October 12, 2012 09:31
channelFoam for a 3D pipe AlmostSurelyRob OpenFOAM 3 June 24, 2011 13:06
Wall function for velocity? johnblund OpenFOAM 0 March 10, 2011 09:50
Need some wall function approaches! yka8150 Main CFD Forum 0 September 21, 2009 23:08
Axisymmetrical mesh Rasmus Gjesing (Gjesing) OpenFOAM Native Meshers: blockMesh 10 April 2, 2007 14:00


All times are GMT -4. The time now is 11:32.