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

LES for 2D case?

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

Reply
 
LinkBack Thread Tools Display Modes
Old   July 30, 2013, 09:58
Default LES for 2D case?
  #1
Member
 
Xiangyin Meng
Join Date: Jun 2012
Location: London
Posts: 66
Rep Power: 4
mxylondon is on a distinguished road
Dear Foamers,

When I use LES model for a 2D case, it suggests that 'LES is not strictly applicable.....'
So, it means it is not ok to use LES for 2D case? A little bit confused.
mxylondon is offline   Reply With Quote

Old   July 30, 2013, 16:51
Default
  #2
Senior Member
 
Nima Sam
Join Date: Sep 2009
Location: Tehran, Iran
Posts: 1,075
Blog Entries: 1
Rep Power: 14
nimasam is on a distinguished road
Send a message via Yahoo to nimasam
it can be used numerically, but when i asked an expert in turbulence it says using LES for 2D cases is non-sense as it LES using spatial filter
__________________
Training Course on OpenFOAM at (http://www.isme.ir/)
My Weblog (http://openfoam.blogfa.com/)
nimasam is offline   Reply With Quote

Old   July 30, 2013, 16:57
Default
  #3
Senior Member
 
Alex
Join Date: Jun 2012
Location: Germany
Posts: 1,034
Rep Power: 17
flotus1 will become famous soon enough
Two-dimensional turbulence has different physical behavior than three-dimensional turbulence.
That is why LES on a 2-dim. domain should not be used to obtain reliable results for 3-dim. flows.
flotus1 is offline   Reply With Quote

Old   July 31, 2013, 03:58
Default
  #4
Member
 
Xiangyin Meng
Join Date: Jun 2012
Location: London
Posts: 66
Rep Power: 4
mxylondon is on a distinguished road
Emmm, I am using a 2D case to test my own developed solver, coz 3D case is bloody time-waste, if put too many grid inside the layer Y+<30.
I mean, is it a possible way to confirm the LES model's working well?
mxylondon is offline   Reply With Quote

Old   July 31, 2013, 06:42
Default
  #5
Senior Member
 
Alex
Join Date: Jun 2012
Location: Germany
Posts: 1,034
Rep Power: 17
flotus1 will become famous soon enough
If you are comparing your results to the results from another 2D LES solver, you should be fine.
flotus1 is offline   Reply With Quote

Old   July 31, 2013, 08:59
Default
  #6
Senior Member
 
Lieven
Join Date: Dec 2011
Location: Mol, Belgium
Posts: 294
Rep Power: 11
Lieven will become famous soon enough
Hi Xiangyin,


Both Alex and Nima are correct. You need to make a distinction between validating your implementation and validating your model.
* If you purely want to validate your solver (so the numerical implementation), you can compare your results with other solvers.
* However, if you want to validate it, doing a 2D LES is basically pure non-sense. Turbulence is by definition a 3D effect. As soons as you neglect this, you will probably end up with pure rubbish.

Cheers,

Lieven
Lieven is offline   Reply With Quote

Old   July 31, 2013, 10:21
Default
  #7
Member
 
Xiangyin Meng
Join Date: Jun 2012
Location: London
Posts: 66
Rep Power: 4
mxylondon is on a distinguished road
Thank you guys! That's really what I want to know.
My plan is to make sure every step is OK before using real 3D running, otherwise it is too long to try something in setup.
Thanks again!
mxylondon 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
Transient case running with a super computer microfin FLUENT 0 March 31, 2009 12:20
How many BC do I need for a single LES case wuwen OpenFOAM Running, Solving & CFD 0 November 17, 2008 08:58
Help! Should I use LES in this case. Thanks. Feng FLUENT 4 April 25, 2008 18:04
Differences between a laminar code and a les one ben Main CFD Forum 9 February 17, 2005 00:40
Body force - Does it work? Jan Rusås CFX 5 August 27, 2002 10:50


All times are GMT -4. The time now is 20:00.