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

how to report y+ in paper?

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

Like Tree1Likes
  • 1 Post By LuckyTran

Reply
 
LinkBack Thread Tools Display Modes
Old   May 15, 2016, 15:46
Default how to report y+ in paper?
  #1
New Member
 
Join Date: Feb 2016
Posts: 19
Rep Power: 2
BigJoe is on a distinguished road
As the title says, when you write an paper, you will mention your turbulence model(k-w SST) and y+. But here y+ is area-weighted average of the whole wall region? or Maximum value? The reason why I ask it is that I will have a a higher y+(1~2) on the other side of the wall when I create a flow angle in transonic flow but the overall area-weighted average is still below 1(0.72)...Anyone has suggestions on how to report y+? or I just report the 'maximum area-weighted average y+ in all cases is 0.72'?
BigJoe is offline   Reply With Quote

Old   May 16, 2016, 10:31
Default
  #2
Senior Member
 
Lucky Tran
Join Date: Apr 2011
Location: Orlando, FL USA
Posts: 1,372
Rep Power: 20
LuckyTran will become famous soon enough
This is also why it's sooooo important to plan your approach. I've always found that it was much better to report cell sizes for this exact reason. In other words, what were your meshing constraints that eventually gave rise to the mesh that would produce such a solution? Cell sizes are unambiguous and give you all the information that you need to repeat the problem, whereas y+ changes depending on the solver and settings used.

The maximum and average value of y+ gives some useful guidelines. The location where the maximum y+ occurs is also very useful, because it tells the next person where they want to focus their attention. Presenting y+ works really well in a presentation, but in a paper, just give me the damn grid spacing and I'll know what your resolution is. I only need to know y+ to understand what modelling regime you are in. e.g. if your mesh is globally y+>30 or globally y+<5. Or some hybrid. The rest of the information is just details. In general, nobody cares if your mesh has an average y+ of 0.1, 0.11, or 0.23. Although there is a "cool factor" to showing off that your y+ is smaller than the next person, do we really need a dick measuring contest in scientific publications? What matters is that y+ ~1. If you are just targeting y+ ~1 then simple state so.

If y+ is very important to your particular scenario, a detailed 1D line plot of y+, 2D contour plot, or full 3D surface plot might be better suited than trying to report a simple number. For example, what information do you want to convey? Use the appropriate figure for doing so.

The real question is: what actually matters?
BigJoe likes this.
LuckyTran is offline   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
Export report value per boundary CfdAero CD-adapco 0 May 28, 2015 18:07
Publish REPORT from a CFD-Post macros rubiconf CFX 0 August 8, 2014 04:58
default values of kOmega (Wilcox) different from paper romant OpenFOAM Running, Solving & CFD 2 August 3, 2011 06:43
How to reference paper which is in review Zonexo Main CFD Forum 4 June 10, 2008 23:13
Report > Discrete Phase > Report > How to commands Francesco Micchetti FLUENT 1 January 23, 2008 07:10


All times are GMT -4. The time now is 00:47.