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

BFS: steady?

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

Reply
 
LinkBack Thread Tools Display Modes
Old   September 9, 1999, 11:03
Default BFS: steady?
  #1
Jan Ramboer
Guest
 
Posts: n/a
Hello,

I am solving a backward facing step at a Re=37000. Stepratio=8/9 and inletvelocity= 44.2m/s From the literature I understood this is a steady-state problem. Howver I have problems with convergence solving this with RANS-Baldwin Lomax model. Now I found an article claiming that it isn't steady-state. What is your opinion on this?

Greetings,

Jan R.
  Reply With Quote

Old   September 9, 1999, 14:04
Default Re: BFS: steady?
  #2
John C. Chien
Guest
 
Posts: n/a
(1). The backward facing step problem is a steady-state problem. (2). Are you using the steady-state formulation or the transient formulation? (3). If you are having the convergence problem with the steady-state formulation, then try to use a more stable first-order scheme to get the converged solution first. From there you can then switch to a high-order method. (4). If you are having the convergence problem with the transient formulation, there is no much you can do, except to use a more smooth mesh, a lower order scheme, and a smaller time step. (5). There could be a feed back effect between the flow field and the turbulence model. So, in this area, you can use a relaxation factor to slow down the change between iterations. (6). It is likely that the method you used is not very stable. This would be the case when using the transient formulation.
  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
Solver for transonic flow? Martin Hegedus OpenFOAM Running, Solving & CFD 21 April 27, 2015 11:02
turbulent channel Flow - simpleFoam Michel_HB OpenFOAM Running, Solving & CFD 2 August 6, 2010 02:07
CFX steady simulation gharek CFX 1 April 7, 2010 18:41
How to determine whether flow is steady or unstead Maliya,Barth Main CFD Forum 7 October 7, 2006 02:26
steady or unsteady? (in dpm) winnie FLUENT 1 April 28, 2003 11:30


All times are GMT -4. The time now is 12:15.