CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > CFX

y+ range

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   March 11, 2009, 04:55
Default y+ range
  #1
Adam Stuchlik
Guest
 
Posts: n/a
if I use SST without transitonal turbulence is it possible that values are wrong calculated when my y+ ranges from ~0.15 up to ~40?? briefly have I to model a grid with 30 < y+ < 300 w/o tt and 1 < y+ < 5 with tt to avoid wrong calculations? best wishes adam
  Reply With Quote

Old   March 11, 2009, 21:24
Default Re: y+ range
  #2
Glenn Horrocks
Guest
 
Posts: n/a
Hi,

It is always possible to get wrong results. There are a lot of things to get right before you get an accurate simulation.

If your question does SST need 30<y+<30 without the transition model and 1<y+1<5 with it the answer is no and no. The normal SST model is good for pretty much any y+ and the transition model requires y+<1.

Regards, Glenn

  Reply With Quote

Old   March 12, 2009, 03:44
Default Re: y+ range
  #3
Adam Stuchlik
Guest
 
Posts: n/a
Yes, this was the question. Thanks.

But how to generate efficiently a y+<1 grid? start with one, looking in post for regions y+>1 and then refining them? Or is there a way to precalculate y+ for a given grid??
  Reply With Quote

Old   March 12, 2009, 16:20
Default Re: y+ range
  #4
Glenn Horrocks
Guest
 
Posts: n/a
Hi,

The manual discusses techniques for estimating necessary grid resolution.

Otherwise do a simulation, work out the y+ and refining/coarsening based on the result.

Glenn Horrocks
  Reply With Quote

Reply


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 Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
unexpected range in pressure level CFD-Post stefank CFX 4 February 2, 2011 05:27
how to create contour surface for some range sa CFX 6 January 28, 2009 14:36
Y+ Range for RNGk-epsilon Turbulence Method Velan Main CFD Forum 1 January 6, 2009 10:50
Y+ range suitable for a 650000Reflow of an airfoil Johari Gregorio FLUENT 0 January 1, 2007 14:46
[OpenFOAM] Automatic range in paraview animations arno ParaView 1 August 29, 2006 04:00


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