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

K-omega SST at values of y+ greater than 1

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

Like Tree3Likes
  • 1 Post By sbaffini
  • 1 Post By sbaffini
  • 1 Post By spelletier

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   July 4, 2019, 22:38
Question K-omega SST at values of y+ greater than 1
  #1
New Member
 
Sebastian Pelletier
Join Date: May 2019
Posts: 12
Rep Power: 7
spelletier is on a distinguished road
Hello all,


I have a rather unique situation that I am not sure exactly how to handle. I am using the kw-SST model to resolve the heat transfer coefficients on an impingement surface at which the y+ is < 1. For this I need the k-w SST model as its one of the best for the impingement case. However my model also has inlet pipes that I don't care about wall fluxes and am simply developing a velocity profile. I would resolve these inlets to a y+ of 1 although the geometry is very prohibitive causing inflation to be not exactly an option and the number of cells needed to be very high.

My question is essentially If I leave the y+ at the inlet pipes greater than 1 in the 30-100 range. Is the kw sst model defaulting to wall functions or will it attempt to resolve and give garbage results? Should I just remove the inlet pipes and develop a separate velocity profile?
spelletier is offline   Reply With Quote

Old   July 5, 2019, 09:21
Default
  #2
Senior Member
 
sbaffini's Avatar
 
Paolo Lampitella
Join Date: Mar 2009
Location: Italy
Posts: 2,176
Blog Entries: 29
Rep Power: 39
sbaffini will become famous soon enoughsbaffini will become famous soon enough
Send a message via Skype™ to sbaffini
It depends from the specific implementation. A wf is just a bc, it has nothing to do, formally, with the kw sst model.

Actually, the model is known to be among the few being able to go down to low y+ values.

Thus, the implementer of the kw sst model in the specific code you are using, might have actually decided to not implement wf at all.

Once you find out what is the specific implementation in the code you are using you will actually find out what is happening at your inlet.
spelletier likes this.
sbaffini is offline   Reply With Quote

Old   July 5, 2019, 09:27
Default
  #3
Senior Member
 
sbaffini's Avatar
 
Paolo Lampitella
Join Date: Mar 2009
Location: Italy
Posts: 2,176
Blog Entries: 29
Rep Power: 39
sbaffini will become famous soon enoughsbaffini will become famous soon enough
Send a message via Skype™ to sbaffini
If you are using Fluent, let me suggest you to either go to that forum or please give people reading you here sufficient contest and interest to answer you here on an otherwise software specific issue.

The fluent implementation of all kw models uses an y+ insensitive wf treatment, which means that your wf will be active wherever y+ is above 3-5
spelletier likes this.
sbaffini is offline   Reply With Quote

Old   July 7, 2019, 20:04
Default
  #4
New Member
 
Sebastian Pelletier
Join Date: May 2019
Posts: 12
Rep Power: 7
spelletier is on a distinguished road
Thank you very much for your time and replies, I was unaware that the wf implementation would be program and not model specific, my apologies. As I am using Fluent you essentially answered my question thank you again
sbaffini likes this.
spelletier is offline   Reply With Quote

Reply

Tags
k-w sst, wall functions, y plus selection

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
oscillatingRotatingMotion: simulation time change with omega and amplitude values decibelle OpenFOAM Running, Solving & CFD 3 November 14, 2018 06:28
Setting change from k omega to k omega SST bingo641 OpenFOAM Programming & Development 0 May 22, 2018 05:15
K-Omega SST BC set up for omega and K joneill053 OpenFOAM Pre-Processing 2 July 10, 2017 14:29
k-w SST freestream values for w hazari.aaquib Main CFD Forum 4 March 18, 2016 04:29
SST k-w model--the parameter 'omega' does not convergence zyy95900 FLUENT 4 May 6, 2012 23:58


All times are GMT -4. The time now is 06:31.