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

extreme strange problem about unsteady calculation

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

Reply
 
LinkBack Thread Tools Display Modes
Old   June 27, 2008, 09:12
Default extreme strange problem about unsteady calculation
  #1
nashiong
Guest
 
Posts: n/a
I'm doing a unsteady calculation about flow past sphere with an acceleration. We know that when Rep<<1, we could describe this flow using N-S equation without convection term. when the Rep number grows larger than 1 as the time goes by, the calculation results seems also to be dominated by N-S equation without convection term!! it means that no matter Stokes force, history force, or added mass force, all just variate linearly, but actually, it should not. I has already try to vary my time step and magnitude of acceleration, but all of them remain ineffective. Is there anyone who ever met a similar problem? thanks a lot for your concerns some paraments: Vstart=0, a=1e-4, time step=0.01 radius of sphere 5e-3, so rep number variates 0.01 each time step
  Reply With Quote

Old   June 27, 2008, 09:22
Default Re: extreme strange problem about unsteady calcula
  #2
nashiong
Guest
 
Posts: n/a
it just seems that fluent sticks to the initial statement even the rep number is growing. (in addition, I use 2ddp to promise the accuracy)
  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
Unsteady calculation. Q FLUENT 2 April 10, 2006 12:29
extreme points problem Lipo Wang Main CFD Forum 2 August 18, 2004 03:15
Need help: strange problem of unsteady B.C. UDF Z. T. FLUENT 0 April 11, 2003 19:03
unsteady calculation bjcz Main CFD Forum 5 May 9, 2002 18:57
Unsteady Calculation Tom Main CFD Forum 4 July 14, 1999 08:12


All times are GMT -4. The time now is 13:45.