CFD Online URL
[Sponsors]
Home > Forums > Main CFD Forum

about the discretization of unsteady term

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

Reply
 
LinkBack Thread Tools Display Modes
Old   May 9, 2004, 17:57
Default about the discretization of unsteady term
  #1
jay
Guest
 
Posts: n/a
Hi..everyone..

I have question for the unsteady methods.

one is three time level method, another is Adam-bashforth methos. Usually, the most of LES is using the adams-bashforth method for the convection terms and the Crank-Bicolson for the diffusion term.

I'm making code for LES using three-time level method(SIMPLE scheme is used)

What's the difference three time level and Adam-Bashforth ones?

Does have any problems if I use the three time level methd in SIMPLE for LES code?

If it is wrong, How to apply the adams-bashforth method to SIMPLE scheme?

Thank you for your concerned

  Reply With Quote

Old   May 10, 2004, 13:01
Default Re: about the discretization of unsteady term
  #2
noName
Guest
 
Posts: n/a
Crank Nicholson is a single step implicit scheme.

Adams Bashforth is a multi-step scheme, which reads as,

u_n+1 = u_n + 1/2*(3*u_n - u_n-1)

I don't know what is a three time level scheme. Most likely, it is a three step scheme (possibly BDF) or a three stage Runge Kutta, (which can be second order accurate at best).

You can find details of such schemes in any numerical book on ODEs. I recommend: E Hairer, SP Norsett and G Wanner, Solving ordinary differential equations, second edition (2 vols.). But it may be too advanced for beginers.

Hope this helps.
  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
advection term discretization N.R. CFX 8 December 8, 2014 15:22
ATTENTION! Reliability problems in CFX 5.7 Joseph CFX 14 April 20, 2010 16:45
Adequate discretization scheme for term titio OpenFOAM Pre-Processing 0 July 17, 2009 13:51
FVM discretization of diffusion term on crvlnr gr Michail Main CFD Forum 3 March 14, 2008 08:52
Convection Term Discretization Maciej Matyka Main CFD Forum 3 October 7, 2004 05:32


All times are GMT -4. The time now is 21:22.