CFD Online Logo CFD Online URL
Home > Forums > Software User Forums > ANSYS > FLUENT

y+ values!!

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

LinkBack Thread Tools Display Modes
Old   June 18, 2009, 05:24
Default y+ values!!
New Member
Chris Turner
Join Date: Jun 2009
Location: Belfast
Posts: 12
Rep Power: 10
chrisoturner is on a distinguished road

I am currently modelling a diffusing cone under steady flow conditions (eventually the model will be under transient flow conditions, but I am using steady flow at the minute to get a better understanding of Fluent).

The y+ values on the wall of the diffuser have a very large range when plotted, the minimum is 28 and the maximum is 834! I'm not sure if this is anywhere near normal? There is a lot of turbulentce in the diffuser, with a large annular votrex forming.

Also, I have used a cooper mesh, which means the cell size actually increases as the diffusers cross sectional area increases, could this be what is causing the variance in y+ value?

Any help would be great!

Thanks in advance

chrisoturner is offline   Reply With Quote

Old   June 18, 2009, 07:55
New Member
Join Date: Jun 2009
Posts: 15
Rep Power: 10
Piotrek is on a distinguished road
you can adapt the mesh in fluent basing on y+ value
Just go to Adapt->Iso-region

basically you want to have the y+ value around 5-30 depending on the model you use
Piotrek is offline   Reply With Quote

Old   June 18, 2009, 10:55
Senior Member
Join Date: Mar 2009
Posts: 133
Rep Power: 10
coglione is on a distinguished road
Just a comment on pioteks post.

using standard wall functions, y+ should be above 30 larger values up to some limit are acceptable! Thus the grid of Chris is not so bad, a refinement of boundary layers should be restricted to values of y+ > ~200 and only necessary, if these values are found in regions of interest = prostcessing.

coglione is offline   Reply With Quote


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
TimeVaryingMappedFixedValue irishdave OpenFOAM Running, Solving & CFD 31 January 25, 2018 04:03
Ensight - node values -cell values leo FLUENT 1 May 12, 2010 08:47
strange node values @ solid/fluid interface - help JB FLUENT 2 November 1, 2008 13:04
node values or cell values? aPpA FLUENT 0 November 10, 2006 09:56
Plotting raw data values Wilesco Siemens 0 January 5, 2006 06:34

All times are GMT -4. The time now is 14:38.