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

FSI time

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

Reply
 
LinkBack Thread Tools Display Modes
Old   April 25, 2008, 12:38
Default FSI time
  #1
YY
Guest
 
Posts: n/a
Hi guys,

I am very confused with the time in an FSI simulation. I'm basically doing an FSI which is steady for both the structural part and fluid part.

The first time which I could set is the Coupling Time. As I know this does not have any meaning in a static analysis, so I just input the total time as 1s and the substep time as 1s as well. Is this correct?

Second, its the time under solver control, I think that is for the fluid part. People have said that its a pseudo time which I dont really know what it means. Anyway i treat this like a substep, so I use a physical time scale and i use a 0.01s time. Does this mean that when CFX solves in 1 stagger iteration, the whole load step which is 1s will be divided into 100 substeps? and if so, if I set the outer loop max iteration to be 100, would it mean 100 for each substep or 100max for the entire 100 substeps. Please advice.

Another thing is for the under-relaxation factor, if I have convergence difficulty say negative volume, do I lower the under relaxation factor or do I lower the pseudo time for the CFD? I am modelling a flow in a pipe where the pipe can be severely collapsed. I would think that its the displacement of the pipe which is too much that is causing the fluid mesh to crash. I tried lowering this under-relaxation factor but the solution crashes earlier. Why is that so? Thanks guys.

  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
SLTS+rhoPisoFoam: what is rDeltaT??? nileshjrane OpenFOAM Running, Solving & CFD 4 February 25, 2013 05:13
Floating point exception error Alan OpenFOAM Running, Solving & CFD 10 April 6, 2012 14:02
Upgraded from Karmic Koala 9.10 to Lucid Lynx10.04.3 bookie56 OpenFOAM Installation 8 August 13, 2011 04:03
Error while running rhoPisoFoam.. nileshjrane OpenFOAM Running, Solving & CFD 8 August 26, 2010 12:50
initial file for fsi modeling? mortazavi CFX 0 July 21, 2009 02:06


All times are GMT -4. The time now is 20:53.