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

Rough wall

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

Like Tree1Likes
  • 1 Post By nellio75

Reply
 
LinkBack Thread Tools Display Modes
Old   November 9, 2009, 11:59
Question Rough wall
  #1
New Member
 
Bruyère
Join Date: Oct 2009
Posts: 9
Rep Power: 8
nellio75 is on a distinguished road
Hello everybody,

Do you have any experience about the rough wall treatment. I want to run simulations with smooth and rough wall : it deals a throttle pressure loss. My problem is to know if I can set as a CFX roughness height hs, the roughness height that I got from a test measure. my measure corresponds to a roughness depth of 1.6 um. So Can I set hs=1.6 um in CFX?

Nota : Sandgrain diameter is hs in CFX : have a look at cfx help about rough wall treatment.

Thanks in advance
nellio75
Attached Files
File Type: doc RoughWallTreatment.doc (41.0 KB, 84 views)
nellio75 is offline   Reply With Quote

Old   November 17, 2009, 04:07
Default
  #2
Senior Member
 
Join Date: Nov 2009
Posts: 125
Rep Power: 8
mactech001 is on a distinguished road
Try the following:
1) Insert a 'Boundary' within your Domain
2) Change 'Boundary type' to 'Wall'
3) Goto 'Boundary Details' tab
4) Expand the 'Wall Roughness' option
5) insert your hs in the 'Roughness Height' in meters
__________________
Thank you for your kind attention.

Kind regards,
mactech001
Currently using: ANSYS v13
mactech001 is offline   Reply With Quote

Old   November 18, 2009, 10:03
Default height of the sand grain
  #3
New Member
 
Bruyère
Join Date: Oct 2009
Posts: 9
Rep Power: 8
nellio75 is on a distinguished road
Thanks for your reply but I'm afraid my question wasn't very understandable : if you have looked at the attached file, I 'm looking for an equivalence between a real measure of a wall roughness and the diameter of a sand grain used in CFX: the sand grain layer is used in CFX to modelise the roughness. Anyway, in the meantime, I've found an extract of a book where there's an example of different real roughness. I think it will be sufficient for the purpose of my study. So I can close my question for this forum.

Anyway, I thank you for having paid attention of my question.

Best Regards
nellio75
nellio75 is offline   Reply With Quote

Old   November 19, 2009, 01:12
Default
  #4
Senior Member
 
Join Date: Nov 2009
Posts: 125
Rep Power: 8
mactech001 is on a distinguished road
Hi nellio75.

glad you've found a possible solution.

would you mind sharing info on the real roughness please?
__________________
Thank you for your kind attention.

Kind regards,
mactech001
Currently using: ANSYS v13
mactech001 is offline   Reply With Quote

Old   November 19, 2009, 06:23
Default
  #5
New Member
 
Bruyère
Join Date: Oct 2009
Posts: 9
Rep Power: 8
nellio75 is on a distinguished road
Please find attached the extract of the book as asked.

Best Regards
Nellio75
Attached Images
File Type: jpg equivlence_schlichting.jpg (90.4 KB, 162 views)
afah7524 likes this.
nellio75 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
Fluent3DMeshToFoam simvun OpenFOAM Other Meshers: ICEM, Star, Ansys, Pointwise, GridPro, Ansa, ... 48 May 14, 2012 05:20
Errors running allwmake in OpenFOAM141dev with WM_COMPILE_OPTION%3ddebug unoder OpenFOAM Installation 11 January 30, 2008 21:30
SST model with rough wall? David CFX 4 November 30, 2005 12:22
Multicomponent fluid Andrea CFX 2 October 11, 2004 05:12
the law of the wall for rough surface maximus Main CFD Forum 0 January 31, 2004 09:45


All times are GMT -4. The time now is 03:10.