CFD Online Logo CFD Online URL
Home > Forums > General Forums > Main CFD Forum

LES,Periodic Boundary Conditions

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

LinkBack Thread Tools Search this Thread Display Modes
Old   January 15, 2003, 12:55
Default LES,Periodic Boundary Conditions
Posts: n/a

I'm conducing a study to insert in an existing CFD code developed in my department a computational model based on LES. Specifically, this is the " Combined LES and time dependent RANS" proposed by Speziale in 1997 (a reference: "A combined Large-Eddies Simulation and Time-Dependent RANS Capability for High-Speed Compressible Flows",C.G.Speziale,Journal of Scientific Computing, Vol 13,No3 ,1998). Briefly: subgrid scale models are dimensionless functions of the computational mesh size times a Reynolds stress model based on a two equations model. A LES go continuously to a RANS computation as the mesh becomes successively more coarse or the Reynolds number becomes much larger ; the level of dicretization is parameterised by the nondimensional ratio of the mesh size to the Kolmogorov length scale. I have to write a new FORTRAN algorithm to insert in the old code, than to test it in the classic backward facing step.

Have you got any experience of this model ? Furthermore, I have some doubt about the lateral boundary conditions in the channel: I must apply periodic boundary conditions, but does this simply mean that the variables (velocity,pressure,ecc.,) are identical but unknowed in the two opposite walls ? And in LES should I make any particular adaptations to impose this conditions?

Thanks for Your help.
  Reply With Quote

Old   January 19, 2003, 08:03
Default Re: LES,Periodic Boundary Conditions
Posts: n/a
hello,I'm a beginer in LES,and i wrote my code using fortran my code does not work well furthermore,i didn't read the paper Combined LES and time dependent RANS?proposed by Speziale in 1997. i use the periodic boundary in my code in spanwise, and set the velocity(pressure,etc) of front as the same as the behind,that is to say the first grid==the lastest grid. Perhaps it's not real! you can read the book "Turbulence:the legacy of Komogrove".
  Reply With Quote

Old   January 21, 2003, 06:44
Default Re: LES,Periodic Boundary Conditions
Posts: n/a
Hi ,Tom I think that the method of Speziale is not the best for a beginner, to understand the LES. I'm also beginner,but i have before studied the theory of the LES,and now i begin the applications. I use periodic conditions in spanwise, but i think that this mean , for example in a channel, that the lateral wall are identical. If the first grid = lastest grid, we have a streamwise periodic condition.


  Reply With Quote


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
Impinging Jet Boundary Conditions Anindya Main CFD Forum 25 February 27, 2016 12:58
symmetry boundary conditions in cfx lost.identity CFX 41 May 22, 2013 07:21
Boundary conditions for 2D Navie-Stockes simulation L1011 OpenFOAM 5 December 13, 2012 08:17
[Commercial meshers] Trimmed cell and embedded refinement mesh conversion issues michele OpenFOAM Meshing & Mesh Conversion 2 July 15, 2005 04:15
A problem about setting boundary conditions lyang Main CFD Forum 0 September 19, 1999 18:29

All times are GMT -4. The time now is 00:41.