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

Minimum Y+?

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

Reply
 
LinkBack Thread Tools Display Modes
Old   April 25, 2008, 07:04
Default Minimum Y+?
  #1
Tom
Guest
 
Posts: n/a
Hi,

Im trying to model flow about a protrution where couette flow is present and was looking at near wall meshing.

From what I've read a Y+ of around 30-100 is optimum in most cases. My meshing currently has a Y+ ranging from around 1-10. Is this a problem? Does it matter that my boundary layers are over refined? Will it mess up the solver's near wall treatment? From what Ive read Y+ is used to approximate a boundary layer profile from minimal points, will fluent use only my first couple of points to approximate the boundary layer instead of the many that are in fact placed in there? If so would it work to simply use adaptive meshing to coarsen the grid to a minimum Y+ of 30?

Any help would be greatly appreciated.

Cheers,

Tom
  Reply With Quote

Old   April 25, 2008, 18:38
Default Re: Minimum Y+?
  #2
AAA
Guest
 
Posts: n/a
Hi

according to the manual, y+ must be in the 30-300 range if you are using the standard wall function, and in the 1-5 range ir you are using the enhanced wall treatment. I suggest you shift to the enhanced wall treatment and start y+ adaption till you get a value in the 1-5 range, otherwise, you probabely have to go back to Gambit and re-mesh. Unfortunately, you can only coarsen your mesh if you have previously refined it in the same case.

Regards

AAA
  Reply With Quote

Old   April 25, 2008, 19:21
Default Re: Minimum Y+?
  #3
Tom
Guest
 
Posts: n/a
Thanks for your help! I did wonder why it wasn't adapting any cells when I tried to coarsen the grid! And switching to enhanced wall treatment certainly seems like a better option than going back to gambit!
  Reply With Quote

Old   April 25, 2008, 19:40
Default Re: Minimum Y+?
  #4
AAA
Guest
 
Posts: n/a
Hi again

This site might be of help to you too

http://geolab.larc.nasa.gov/APPS/YPlus/

Regards

AAA
  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
Minimum yplus for SST EBM CFX 2 January 28, 2009 19:09
Scalar Below minimum James CD-adapco 0 November 9, 2004 11:44
XY plot minimum? HP FLUENT 2 August 27, 2004 10:50
What will be the minimum scale? windhair CFX 1 August 19, 2004 18:23
Minimum timestep Pascale Fonteijn CFX 3 June 10, 2003 04:53


All times are GMT -4. The time now is 02:40.