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

Yplus

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

Like Tree3Likes
  • 2 Post By sbaffini
  • 1 Post By sbaffini

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   June 20, 2013, 16:37
Default Yplus
  #1
Member
 
rayan
Join Date: Jun 2013
Posts: 65
Rep Power: 12
rayan24 is on a distinguished road
Hi,

I want to know what's the "Y+" and what's the effect of YPLUS, WHY i MUST CHOISE az define value for Yplus,

in LES model why i must choise Yplus =1?

Thanks for your explications
rayan24 is offline   Reply With Quote

Old   June 21, 2013, 05:22
Default reply of Y+
  #2
New Member
 
CHAO
Join Date: Feb 2013
Posts: 6
Rep Power: 13
CONVERGE LEARNER is on a distinguished road
Hi.
Y+ represents the suitability evaluation of boundary layer thickness.
CONVERGE LEARNER is offline   Reply With Quote

Old   June 21, 2013, 07:50
Default
  #3
Senior Member
 
sbaffini's Avatar
 
Paolo Lampitella
Join Date: Mar 2009
Location: Italy
Posts: 2,149
Blog Entries: 29
Rep Power: 39
sbaffini will become famous soon enoughsbaffini will become famous soon enough
Send a message via Skype™ to sbaffini
Y+ is importsant in relation to the known features of turbulent velocity profiles near the wall. For Equilibrium boundary layers, at low y+ (<5) it is linear, for high values (>30-50) and up to 0.1 delta (thickness of the boundary layer) it is logarithmic. For the first point near the wall in your grid you can define a value for y+, then you know if it is too high to resolve the full velocity profile or not. If not, you need a low Re turbulence model (which can go down to the wall), otherwise you will need a standard model with wall functions.

This is the basic matter in RANS.

For LES it is quite different and y+ alone is useless. Wall parallel grid spacings matters as well. But this is a much longer story...
aylalisa and rayan24 like this.
sbaffini is offline   Reply With Quote

Old   June 21, 2013, 08:05
Default another question
  #4
New Member
 
CHAO
Join Date: Feb 2013
Posts: 6
Rep Power: 13
CONVERGE LEARNER is on a distinguished road
That is a wonderful explanation.
Well,may I know if you know about the Detailed chemical reaction mechanism of gasoline and suitable references on this matter? Any help would be greatly appreciated.
CONVERGE LEARNER is offline   Reply With Quote

Old   June 21, 2013, 08:07
Default
  #5
Senior Member
 
sbaffini's Avatar
 
Paolo Lampitella
Join Date: Mar 2009
Location: Italy
Posts: 2,149
Blog Entries: 29
Rep Power: 39
sbaffini will become famous soon enoughsbaffini will become famous soon enough
Send a message via Skype™ to sbaffini
I'm sorry, but this not my field of experience.

Regards
rayan24 likes this.
sbaffini is offline   Reply With Quote

Old   June 21, 2013, 09:48
Default
  #6
Member
 
rayan
Join Date: Jun 2013
Posts: 65
Rep Power: 12
rayan24 is on a distinguished road
Verry good explanation

Thanks a lot I begin to undestund the importance of Y+

Thanks


Quote:
Originally Posted by sbaffini View Post
Y+ is importsant in relation to the known features of turbulent velocity profiles near the wall. For Equilibrium boundary layers, at low y+ (<5) it is linear, for high values (>30-50) and up to 0.1 delta (thickness of the boundary layer) it is logarithmic. For the first point near the wall in your grid you can define a value for y+, then you know if it is too high to resolve the full velocity profile or not. If not, you need a low Re turbulence model (which can go down to the wall), otherwise you will need a standard model with wall functions.

This is the basic matter in RANS.

For LES it is quite different and y+ alone is useless. Wall parallel grid spacings matters as well. But this is a much longer story...
rayan24 is offline   Reply With Quote

Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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 Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
[Other] Contribution a new utility: refine wall layer mesh based on yPlus field lakeat OpenFOAM Community Contributions 58 December 23, 2021 03:36
How can Modify yPlus function to be yPlus not yStar? immortality OpenFOAM Running, Solving & CFD 0 May 5, 2013 14:16
which yplus (SST) sanchezz CFX 17 January 11, 2010 05:45
X-Y plot of Yplus in Fluent 5.3 Luo FLUENT 24 April 11, 2000 07:07
heat transfer coefficients with "bad" yplus Andrew Main CFD Forum 4 April 8, 1999 05:43


All times are GMT -4. The time now is 03:49.