 |
 |
 |
|
|
|
[Sponsors] | ||||
June 1, 2010, 04:40
|
unsteady divergence simple case
|
#1 |
|
New Member
Francis
Join Date: Apr 2010
Posts: 13
Rep Power: 16  |
im curently workin on a cylindrical obstacle in a pipe... i hav some convergence issues...my calculation is unsteady.
i really need help, regards |
|
|
|
|
|
June 9, 2010, 08:21
|
Timestep control
|
#2 |
|
Super Moderator
Hans Bihs
Join Date: Jun 2009
Location: Trondheim, Norway
Posts: 377
Rep Power: 17 |
Hei,
possibly your time step is too large. Especially if you use explicit time treatment or implicit time stepping without under relaxation, high CFL numbers (CFL>1) cause numerical instability. In case you use your own program and have access to the source code, consider adaptive timestep control. Regards Hans |
|
|
|
|
|
|
June 10, 2010, 04:24
|
|
#3 |
|
New Member
Francis
Join Date: Apr 2010
Posts: 13
Rep Power: 16 |
my parameters are fine. i changed the URF's and it is workin but i had to increase the inner iterations...at least it is converging even if itll be longer
by the way im using implicit scheme with URF's regards, Francis |
|
|
|
|
|
 |
|
|
Similar Threads
|
||||
| Thread | Thread Starter | Forum | Replies | Last Post |
| autosave output of x-y plot for unsteady case | Eric | Siemens | 3 | August 10, 2008 03:35 |
| how to predict unsteady flow from case definition? | Felix | Main CFD Forum | 6 | August 28, 2007 16:40 |
| Simple Q. How to complete a Case? | W.A. | Siemens | 3 | April 23, 2006 19:41 |
| Unsteady SIMPLE solver | hani | OpenFOAM Running, Solving & CFD | 3 | October 25, 2005 13:43 |
| Unsteady state case setup | Christian | FLUENT | 2 | February 16, 2003 17:11 |
Linear Mode
