|
[Sponsors] |
Difference results between Steady and Unsteady? |
|
LinkBack | Thread Tools | Search this Thread | Display Modes |
April 30, 2004, 06:51 |
Difference results between Steady and Unsteady?
|
#1 |
Guest
Posts: n/a
|
Hi all! I got different results when I change my model from steady to unsteady state (both states are converged successfully). What makes the unsteady results differ from the steady ones with the same conditions? thanks for help. Giang T Vu
|
|
April 30, 2004, 09:00 |
Re: Difference results between Steady and Unsteady
|
#2 |
Guest
Posts: n/a
|
I think in steady State in the Navier stokes equation they do not have transient terms. While in unsteady State case they have it. When you are problem is steady you will get convergence whether you use steady State or unsteady State solver. Pratap
|
|
April 30, 2004, 09:01 |
Re: Difference results between Steady and Unsteady
|
#3 |
Guest
Posts: n/a
|
I think in steady State in the Navier stokes equation they do not have transient terms. While in unsteady State case they have it. When you are problem is steady you will get convergence whether you use steady State or unsteady State solver. bob
|
|
May 1, 2004, 06:15 |
Re: Difference results between Steady and Unsteady
|
#4 |
Guest
Posts: n/a
|
Thanks Bob, yes, mine is a steady state problem, when I change to run it under unsteady state it should give me the same result, correct? What would you say if I got the same pressure and velocity distribution and DIFFERENT vapor product (I'm modeling cavitation) when I switch from steady to unsteady mode?
|
|
May 4, 2004, 04:24 |
Re: Difference results between Steady and Unsteady
|
#5 |
Guest
Posts: n/a
|
hi giang
what about your time step size and time dicretisation scheme? |
|
May 6, 2004, 10:07 |
Re: Difference results between Steady and Unsteady
|
#6 |
Guest
Posts: n/a
|
Hi Vladimir, The time step size deduced from Courant number and I estimated around 0.001. I used 1st order implicit segregated solver with standard k-epsilon turbulent model. Giang.
|
|
May 22, 2004, 07:37 |
Re: Difference results between Steady and Unsteady
|
#7 |
Guest
Posts: n/a
|
I'm confused, how can an unsteady and a steady simulation give the same answer ? For an unsteady simulation you have transient effects, pertubations in the flow etc which if averaged over enough time, MAY give you a similar result to a steady state simulation, but more by luck than anything else ? or is my understanding of steady and unsteady not correct ?? Bob
|
|
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
What difference is betw. steady and unsteady simul | matrix-1.0 | FLUENT | 3 | August 5, 2007 11:30 |
using steady state results for unsteady flow | siva appanna | Main CFD Forum | 3 | February 20, 2006 06:29 |
Unsteady vs Steady simulation - any difference? | Sally | Main CFD Forum | 16 | December 16, 2005 10:15 |
steady or unsteady? (in dpm) | winnie | FLUENT | 1 | April 28, 2003 12:30 |
About the difference between steady and unsteady problems | Lisa | Main CFD Forum | 11 | July 5, 2000 15:37 |