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

scalable wall function, 3<y+<11

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

Reply
 
LinkBack Thread Tools Display Modes
Old   March 20, 2013, 00:55
Default scalable wall function, 3<y+<11
  #1
Senior Member
 
François Grégoire
Join Date: Jan 2010
Location: Laval University, Canada
Posts: 366
Rep Power: 8
macfly is on a distinguished road
I obtain a wide range of y+ values (5-200) with a coarse mesh, realizable k-e and scalable wall function. And there is lots of y+ values (40 %) in the buffer layer, which is supposed to be pretty bad.

Is it a good idea to use scalable wall function and refine only the first layer of near-wall mesh in order to obtain 100 % of y+<11? Heat transfer will be included in the model eventually. I can't afford a fine mesh with y+<1 and 10-20 layers on the walls. Geometry is too complex and conditions are changing significantly in time, so adjusting the mesh locally is not an option either.

Thanks ahead for your suggestions
macfly is offline   Reply With Quote

Old   December 10, 2014, 11:13
Default
  #2
Member
 
Andrea
Join Date: Feb 2012
Location: Leeds, UK
Posts: 79
Rep Power: 6
Andrea1984 is on a distinguished road
Hi,

I know it is a quite an old post but I find myself in exactly the same situation. What approach did you follow?

Cheers
Andrea
Andrea1984 is offline   Reply With Quote

Old   December 10, 2014, 22:53
Default
  #3
Senior Member
 
François Grégoire
Join Date: Jan 2010
Location: Laval University, Canada
Posts: 366
Rep Power: 8
macfly is on a distinguished road
In the end I used enhanced wall treatment because it blends linear and logarithmic laws. From theory guide 15.0 section 4.14.5.2: This formula also guarantees the correct asymptotic behavior for large and small values of y+ and reasonable representation of velocity profiles in the cases where y+ falls inside the wall buffer region (3 < y+ < 10).
macfly is offline   Reply With Quote

Old   December 11, 2014, 06:55
Default
  #4
Member
 
Andrea
Join Date: Feb 2012
Location: Leeds, UK
Posts: 79
Rep Power: 6
Andrea1984 is on a distinguished road
I was thinking to do the same. What do you reckon is the minimum number of prism layers to be used with this approach? I am aware that if you want to integrate NS equations up to the wall (i.e. EWT with first cell y+ at about 1) you need at least 10 cells within the boundary layer.

However this not the approach I am going to follow, since most of my cells are in the log layer (y+ of about 60) and I only have three prism layers. Is that enough with EWT? and with scalable wall functions?

Andrea
Andrea1984 is offline   Reply With Quote

Old   December 11, 2014, 10:52
Default
  #5
Member
 
davide basso
Join Date: Jan 2012
Posts: 47
Rep Power: 5
rolloblues is on a distinguished road
Hi all,

since (if I got it right) near wall analysis it's not a goal for you, maybe you could just coarsen the mesh in order to have y+>30 everywhere and then use the standard wf.
rolloblues 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
Radiation interface hinca CFX 15 January 26, 2014 18:11
error message with modeling a cube with a hold at the center hsingtzu OpenFOAM Native Meshers: blockMesh 2 March 14, 2012 10:56
channelFoam for a 3D pipe AlmostSurelyRob OpenFOAM 3 June 24, 2011 13:06
ParaView for OF-1.6-ext Chrisi1984 OpenFOAM Installation 0 December 31, 2010 07:42
Wall function in adverse pressure gradients stephane baralon Main CFD Forum 11 September 2, 1999 04:05


All times are GMT -4. The time now is 04:23.