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

hybrid RANS/LES in CFX?

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

Reply
 
LinkBack Thread Tools Display Modes
Old   February 17, 2009, 01:00
Default hybrid RANS/LES in CFX?
  #1
Hao
Guest
 
Posts: n/a
Hi, does anybody know whether hybrid RANS/LES simulation is feasible in ANSYS CFX or not?
  Reply With Quote

Old   February 17, 2009, 17:57
Default Re: hybrid RANS/LES in CFX?
  #2
Glenn Horrocks
Guest
 
Posts: n/a
Hi,

The SAS and DES turbulence models are hybrid RANS/LES models. I think you will find CFX is the best commercial code for hybrid RANS/LES models because of these options.

Glenn Horrocks
  Reply With Quote

Old   February 20, 2009, 01:31
Default Re: hybrid RANS/LES in CFX?
  #3
Hao
Guest
 
Posts: n/a
Thanks for the reply, Glenn. Is it possible to realize a zonal hrbrid RANS/LES simulation by using multiply domains in CFX?
  Reply With Quote

Old   February 24, 2009, 17:32
Default Re: hybrid RANS/LES in CFX?
  #4
Glenn Horrocks
Guest
 
Posts: n/a
Sorry, I don't know what you mean. Read the CFX documentation and/or talk to CFX support for further details of what is possible with SAS and DES.

Glenn Horrocks
  Reply With Quote

Old   February 25, 2009, 04:38
Default Re: hybrid RANS/LES in CFX?
  #5
Timon
Guest
 
Posts: n/a
I guess he means to ask if it's possible to assign different turbulence models for separated domains. If so: no this not possible, you need to use the same turbulence model everywhere.

The RANS/LES switch in DES is based on the local turbulence length scale and local grid scale, switching on LES when the grid is sufficiently fine to represent the local eddy size.

SAS is not a hybrid method, but basically an URANS method in which the resolved turbulence length is locally adaptive.

Note that there is a distinction between hybrid RANS-LES and DES. Hybrid RANS-LES is a zonal approach: SST in one domain and LES in the other domain. The SGS-model is then a typical LES-SGS model, e.g. Smagorinsky. DES is an adaptive approach, where all eddy sizes that cannot be represented by the grid are modeled with RANS. The SGS model used in LES-mode is RANS as well (as opposed to e.g. Smagorinsky in normal LES).
  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
[ICEM] Proper way to name boundaries on 2D model for use in CFX? RossFS ANSYS Meshing & Geometry 4 November 10, 2011 03:38
Pros and Cons for CFX, CFdesign, COMSOL Val Main CFD Forum 3 June 10, 2011 02:20
PhD using CFX Rui CFX 9 May 28, 2007 05:59
Can CFX Automatically generate hybrid meshes? JJ CFX 0 August 28, 2003 21:18
CFX 4.4 installation problem Pandu Sattvika CFX 1 December 1, 2001 05:07


All times are GMT -4. The time now is 02:41.