CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > OpenFOAM > OpenFOAM Running, Solving & CFD

Rough baundary in atmospheric wind

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   August 18, 2008, 09:51
Default Hi! I am modeling the wind
  #1
New Member
 
Majid Hojjat
Join Date: Mar 2009
Location: Munich, Germany
Posts: 3
Rep Power: 17
majidhojjat is on a distinguished road
Hi!

I am modeling the wind effect on a cubic building. and first, to get the proper approaching flow (similar to experimental data) I am modeling an empty wind channel.
prescribing the inlet velocity, I produce the Ux profile. but for turbulence intensity (or k) using the inlet is not hopeful and I guess I should use a rough wall function to get the desired profile.

I tried using nutStandardRoughWallFunction but it was not really effective. even changing value of roughness length or... did not change anything.
To have a rough wall, is it enough just to add nutStandardRoughWallFunction as the physical type in boundary file and to specify roughness length and other parameters in /0/k ?

I am using OF 1.4.1 and I tried the mentioned problem in kEpsilon and kOmegaSSt as well as LES models.

Thanks!
majidhojjat is offline   Reply With Quote

Old   August 18, 2008, 10:11
Default nut boundary conditions are on
  #2
Senior Member
 
Eugene de Villiers
Join Date: Mar 2009
Posts: 725
Rep Power: 21
eugene is on a distinguished road
nut boundary conditions are only effective in conjunction with the SpalartAllmaras model.
eugene is offline   Reply With Quote

Old   August 18, 2008, 10:30
Default thank you for your answer, so
  #3
New Member
 
Majid Hojjat
Join Date: Mar 2009
Location: Munich, Germany
Posts: 3
Rep Power: 17
majidhojjat is on a distinguished road
thank you for your answer,
so, there is no ready rough wall function to be used in other models?
and to maintain turbulence intensity profile I just have the choice of modifying the inlet values?
majidhojjat is offline   Reply With Quote

Old   August 18, 2008, 11:15
Default For the other models the wall
  #4
Senior Member
 
Eugene de Villiers
Join Date: Mar 2009
Posts: 725
Rep Power: 21
eugene is on a distinguished road
For the other models the wall functions are hard-coded.

Not sure about the turbulence intensity profile.
eugene is offline   Reply With Quote

Reply


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
flow in rough pipes Purushotham FLUENT 0 April 17, 2007 05:06
Atmospheric Wind Profile - Inlet Subroutine Roger Siemens 3 December 12, 2002 10:00
Rough walls in CFX 4.X Søren Pedersen CFX 0 March 12, 2002 05:38
Rough Walls in CFX4.x David Hargreaves Main CFD Forum 2 August 23, 1998 09:52


All times are GMT -4. The time now is 09:14.