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

LES Starting Conditions

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

Reply
 
LinkBack Thread Tools Display Modes
Old   August 4, 2003, 05:31
Default LES Starting Conditions
  #1
Bob
Guest
 
Posts: n/a
Hi, I'm wanting to do an LES simulation of flow around a circular cylinder using CFX5.6. Due to the small time steps required for the simulation I was wondering if the following would be a valid option. Start my simulation with a much larger time step - say 2 orders of magnitude, then once I have something representing a steady oscilation of my forces on the cylinder, then drop the timestep back down to the lower desirable level (1e-4sec). The other option I thought of was to use a restart from a transient ke model which I ran and then just use the small time step right from the start. Are there any issues I should be wary about if I adopt either approach ? Cheers for any help Bob
  Reply With Quote

Old   August 8, 2003, 07:02
Default Re: LES Starting Conditions
  #2
sudar
Guest
 
Posts: n/a
Hi. I am also working in LES with CFX, but using the TASCflow for the same. There are two option available in TASCflow for LES models. viz. Samgorinsky and dynamic model. where as in CFX5.6 there is only one model implementedi.e. Smagorinsky. regarding the part of the initialisation, I also still doubtful over this issue. But firstly starting with a traditional k-e model and then shifting to LES model is a good choice, I feel. So once the flow has traversed through the domain, you can switch to the LES model and use an appropriate time step.
  Reply With Quote

Old   August 8, 2003, 07:06
Default Re: LES Starting Conditions
  #3
Bob
Guest
 
Posts: n/a
Cheers Sudar I guess its the only reasonable approach, else excessive solution time is waisted. Bob
  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
LES basic and simple questions. dshawul Main CFD Forum 0 October 4, 2010 10:56
Turbulence dampening due to magnetic field in LES and RAS eelcovv OpenFOAM 0 June 8, 2010 11:35
LES grid mesh L3munoz Main CFD Forum 0 April 7, 2010 05:05
LES and combustion model Margherita Cadorin CFX 0 October 29, 2008 06:24
Differences between a laminar code and a les one ben Main CFD Forum 9 February 17, 2005 00:40


All times are GMT -4. The time now is 07:18.