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

3D LES simulation of a circular cylinder

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   June 19, 2005, 01:35
Default 3D LES simulation of a circular cylinder
  #1
fpz
Guest
 
Posts: n/a
Hi Everybody! I am simulating a circular cylinder by using 3D LES. It puzzled me that I can not get a perfact harmonic time sequence of lift coefficent. However I can do it by using other methods such as k-e model. Considering LES can get more information of fluctuating velocity, Is it a nessary of reasonable result by using 3D LES? Thanks!
  Reply With Quote

Old   June 20, 2005, 05:25
Default Re: 3D LES simulation of a circular cylinder
  #2
andy
Guest
 
Posts: n/a
Why do you expect a perfect harmonic time sequence? Have you compared with measurments or LES simulations of other researchers at the flow conditions you are studying?

Vortex shedding does not always produce a pure tone and this may well be the case for the flow you are studying. On the other hand, you may have numerical, modelling or bug issues with the code.

LES is a substantially more reasonable modelling assumption for large scale vortical motions than eddy viscosity models like ke which represent all the turbulent transport with a big diffusion coefficient. However, this is not necessarily the case near the surface of the cylinder where the modelling assumptions in typical LES codes can be relatively poor.
  Reply With Quote

Old   June 20, 2005, 13:21
Default Re: 3D LES simulation of a circular cylinder
  #3
Mani
Guest
 
Posts: n/a
If you should expect a perfect periodic solution mainly depends on the Reynolds number. In the 2D laminar case, yes, it should be perfectly periodic. In your 3D turbulent case I wouldn't expect that. The easy way to find out: Look at other researcher's results (experiments and computations). You will find that a lot of people did this with RANS and LES already, so you should be able to verify your results.
  Reply With Quote

Old   June 20, 2005, 20:50
Default Re: 3D LES simulation of a circular cylinder
  #4
fpz
Guest
 
Posts: n/a
Thanks!(no content)
  Reply With Quote

Reply

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
benchmark: flow over a circular cylinder goodegg Main CFD Forum 12 January 22, 2013 12:47
Circular cylinder delayed separation on star-ccm+ lovecraft22 STAR-CCM+ 6 March 9, 2010 18:24
Turbulent steady flow around a circular cylinder Mirek Kabacinski FLUENT 0 July 23, 2003 19:40
LES: vortex shedding past a 2D and 3D circular cylinder Rocchi Daniele Main CFD Forum 7 April 9, 1999 13:05
Simulation of the Flow past a circular cylinder using STAR-CD M. S. GUEROUACHE Main CFD Forum 0 October 1, 1998 11:51


All times are GMT -4. The time now is 04:56.