CFD Online Logo CFD Online URL
Home > Forums > Software User Forums > Siemens

coarse grid to fine grid crashing

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

LinkBack Thread Tools Search this Thread Display Modes
Old   February 22, 2005, 10:58
Default coarse grid to fine grid crashing
Posts: n/a

I have a quick question,

First, we ran transient successfully with a coarse grid. After using the coarse grid solution to restart the fine grid case using the same time step and the default solution parameters, the code crashed with negative densities. Is this a symptom of having too big a time step or relaxation parameters? Can anyone recommend some values?
  Reply With Quote

Old   February 22, 2005, 12:27
Default Re: coarse grid to fine grid crashing
Posts: n/a
The Courant number is inversely proportional to the cell size, so if you have the same velocity and time-step, Co will increase. The higher Co, the more likely instability. If you refine the mesh, it's good practice to reduce the time-step accordingly.
  Reply With Quote


Thread Tools Search this Thread
Search this Thread:

Advanced Search
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 Off
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
HOW turbulene Grid (avoid too fine or too coarse)? Toulouser FLUENT 1 February 1, 2007 03:47
Nonlinear Multigrid: Coarse Grid Operators Greg Lewin Main CFD Forum 0 December 1, 2006 09:39
CFdesign behaviour in coarse and fine mesh Farhad Autodesk Simulation CFD 0 May 30, 2006 10:10
How to coarse my grid Luca Main CFD Forum 0 March 15, 2006 02:56
Fine grid embedding Philip Peeples Phoenics 1 July 3, 2002 18:32

All times are GMT -4. The time now is 03:16.