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

Wall functions!

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

Reply
 
LinkBack Thread Tools Display Modes
Old   September 19, 2002, 08:44
Default Wall functions!
  #1
stephen
Guest
 
Posts: n/a
What is the general concenous on the aplication of wall functions within turb models? i.e. the use of adaptive grid, coles Law, shape function, etc.
  Reply With Quote

Old   September 20, 2002, 04:17
Default Re: Wall functions!
  #2
S. S. Mudathir
Guest
 
Posts: n/a
Although I will not directly answer your questions (because I don't know the answers) but i may direct you to where you might get them. In an adaptive grid, the physics of the problem at hand must ultimately direct the grid points to distribute themselves so that a functional relationship on these points can represent the physical solution with sufficient accuracy. The idea is to have the grid points move as the physical solution develops, concentrating in regions of large variation in the solution as they emerge. The mathematics controls the points by sensing the gradients in the evolving physical solution, evaluating the accuracy of the discrete representation of the solution, communicating the needs of the physics to the points, and finally by providing mutual communication among the points as they respond to the physics. The basic techniques involved then are as follows:

(1) a means of distributing points over the field in an orderly fashion, so that neighbors may be easily identified and data can be stored and handled efficiently.

(2) a means of communication between points so that a smooth distribution is maintained as points shift their position.

(3) a means of representing continuous functions by discrete values on a collection of points with sufficient accuracy, and a means for evaluation of the error in this representation.

(4) a means for communicating the need for a redistribution of points in the light of the error evaluation, and a means of controlling this redistribution.

for further information on the grid problem you can contact the good text (availabe online) about the numerical grid generation: http://www.erc.msstate.edu/publications/gridbook/ The whole chapter XI in this book is about adaptive grids so you might get the answer there. About the shape functions you can contact of the good reference of the finite elements, the shape function is heavily discussed.
  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
Modelling Turbulent Wall Functions victorwfreire CFX 11 January 14, 2015 16:48
LES with wall functions, wall boundary, Re 10000 subba CFX 4 July 10, 2007 05:04
Wall Functions pierre OpenFOAM Running, Solving & CFD 0 October 1, 2005 13:13
Wall functions - iterative approach agg Main CFD Forum 1 May 13, 2005 12:25
LES wall functions barrat Main CFD Forum 10 September 1, 2004 08:29


All times are GMT -4. The time now is 06:14.