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

"divergence detected in AMG solver: omega"

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

Reply
 
LinkBack Thread Tools Display Modes
Old   June 14, 2010, 05:13
Default "divergence detected in AMG solver: omega"
  #1
New Member
 
Jon
Join Date: Mar 2010
Posts: 10
Rep Power: 7
Sidewinder is on a distinguished road
I am having a problem with my simulation for university. I keep getting this error:

divergence detected in AMG solver: omega

I have tried changing the relaxation factors for the turbulence and the specific dissipation rate. But to no success. the gas is compressbile and I have specified a mass flow inlet and a pressure outlet. I am using the k-omega model for this simulation.
But i cant seem to get away from this error. I am thinking to turn off the energy equation.

Does enybody have some help or hints for me? I would greatly appreciate it.

Thanks!

Last edited by Sidewinder; June 17, 2010 at 05:01.
Sidewinder is offline   Reply With Quote

Old   March 6, 2012, 17:41
Default
  #2
Member
 
Arun
Join Date: Mar 2012
Location: Vellore,TN,India
Posts: 35
Rep Power: 5
arunintn is on a distinguished road
Hi,
I have the same error. I'm doing analysis on T106A turbine blade simuli. I think you have the solution for that. If it so please let me know what is the solution.
Thank you
arunintn is offline   Reply With Quote

Old   March 7, 2012, 01:11
Default
  #3
Member
 
arjun
Join Date: Oct 2011
Location: Tokyo, JAPAN
Posts: 66
Rep Power: 5
arjun3020 is on a distinguished road
in URF go to advance settings, and change the cycle to F.
arjun3020 is offline   Reply With Quote

Old   March 7, 2012, 04:45
Default
  #4
Member
 
Arun
Join Date: Mar 2012
Location: Vellore,TN,India
Posts: 35
Rep Power: 5
arunintn is on a distinguished road
Quote:
Originally Posted by arjun3020 View Post
in URF go to advance settings, and change the cycle to F.
thanks for replying.. I have another problem divergence detected in AMG solver: Temperature". I like to know this troubleshooting method. I quit new to CFD.
arunintn is offline   Reply With Quote

Old   March 9, 2012, 00:57
Default
  #5
Member
 
arjun
Join Date: Oct 2011
Location: Tokyo, JAPAN
Posts: 66
Rep Power: 5
arjun3020 is on a distinguished road
Reduce URf for temperature. and check all Boundary conditions. hope it will help.
arjun3020 is offline   Reply With Quote

Old   March 9, 2012, 06:50
Default
  #6
Member
 
Arun
Join Date: Mar 2012
Location: Vellore,TN,India
Posts: 35
Rep Power: 5
arunintn is on a distinguished road
I solved the problem.. I made some mistake in boundary.. thank you for you help
arunintn is offline   Reply With Quote

Old   March 10, 2012, 01:15
Default
  #7
Member
 
arjun
Join Date: Oct 2011
Location: Tokyo, JAPAN
Posts: 66
Rep Power: 5
arjun3020 is on a distinguished road
Ok... these are common errors with fluent, to resolve it 1. check URF.
2. Check BC
3. Change advance cycle to F.
arjun3020 is offline   Reply With Quote

Old   March 10, 2012, 06:33
Default
  #8
New Member
 
lida
Join Date: Feb 2012
Posts: 4
Rep Power: 5
wujinlao5 is on a distinguished road
hi ,man
there are 5 to 6 dropdown list in urf advance setting ,x-momnetum\y-momnetum...
when you say " change cycle to F" for this problem, which one do you refer to?
dont tell me it is the omega relevant one.
Quote:
Originally Posted by arjun3020 View Post
Ok... these are common errors with fluent, to resolve it 1. check URF.
2. Check BC
3. Change advance cycle to F.
wujinlao5 is offline   Reply With Quote

Old   June 9, 2012, 10:02
Default
  #9
New Member
 
Fariborz Soroush
Join Date: Oct 2009
Location: Tehran, Iran
Posts: 14
Rep Power: 7
faudiS8 is on a distinguished road
I've the same problem
what do you mean by advanced cycle while there is not such a thing in Under relaxation factors section!?
Thanks for clarification
faudiS8 is offline   Reply With Quote

Old   June 10, 2012, 02:07
Default
  #10
Member
 
Arun
Join Date: Mar 2012
Location: Vellore,TN,India
Posts: 35
Rep Power: 5
arunintn is on a distinguished road
Quote:
Originally Posted by faudiS8 View Post
I've the same problem
what do you mean by advanced cycle while there is not such a thing in Under relaxation factors section!?
Thanks for clarification
you need to find this option in advanced settings and you'll get a pop-up window.

My case i don't need to switch on energy equation because i'm not finding temperature. My problem converged after i switched off the energy equation. If possible you can tell me what you are doing?
arunintn is offline   Reply With Quote

Old   June 10, 2012, 03:35
Default
  #11
New Member
 
Fariborz Soroush
Join Date: Oct 2009
Location: Tehran, Iran
Posts: 14
Rep Power: 7
faudiS8 is on a distinguished road
Quote:
Originally Posted by arunintn View Post
you need to find this option in advanced settings and you'll get a pop-up window.

My case i don't need to switch on energy equation because i'm not finding temperature. My problem converged after i switched off the energy equation. If possible you can tell me what you are doing?
hi
I'm modeling combustion and when I change the density calculation method to ideal gas this problem happens. How do I cope with? I let incompressible ideal gas method to iterate enough (about 300) and then it's residuals are little enough. So by changing to ideal gas method, it converges.
but it's still a question for me!
where is the advanced setting option in the window you say!?
Do we talk about the following link's window!?(Under relaxation window)
http://hpce.iitm.ac.in/website/Manua...ution_Controls

thanks alot
faudiS8 is offline   Reply With Quote

Old   June 10, 2012, 04:02
Default
  #12
Member
 
Arun
Join Date: Mar 2012
Location: Vellore,TN,India
Posts: 35
Rep Power: 5
arunintn is on a distinguished road
I have attached a picture file. I think you can find now. Pleas let me know your fluent version. I'm using Fluent 13.

I like to say URF is is an advanced settings. Try to be careful when you work in that.
Attached Images
File Type: jpg CFD.jpg (67.6 KB, 53 views)
arunintn is offline   Reply With Quote

Old   June 10, 2012, 07:57
Default
  #13
New Member
 
Fariborz Soroush
Join Date: Oct 2009
Location: Tehran, Iran
Posts: 14
Rep Power: 7
faudiS8 is on a distinguished road
goood!
I found out why! I use Fluent 6.3.26! the last dedicate fluent version)
Ansys in 13 version change it too much! Also I think This option- means F cycle- is available for multigrid, isn't it?
by the way....thank you for your attachment!
faudiS8 is offline   Reply With Quote

Old   June 27, 2012, 04:31
Default
  #14
New Member
 
Fariborz Soroush
Join Date: Oct 2009
Location: Tehran, Iran
Posts: 14
Rep Power: 7
faudiS8 is on a distinguished road
hi every body
the problem i found! for changing the solver scheme to F-cycle in fluent 6.3.26 you may go to this path:
Solve>Control>Multigrids...>
here a window will be opened and you may change to F-cycle.

Note: I would appreciate any one who help me to find out the exact mechanism change by this method. In the other words I want to know how this mechanism works, why it diverges, and what does this scheme change do. I heard of a CFD book by someone like choe(?!?) on this. but i'm not sure.
faudiS8 is offline   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
Divergence detected in AMG solver: pressure correction jimmer FLUENT 2 August 7, 2010 06:47
AMG solver _divergence detected Shamoon FLUENT 6 March 11, 2009 08:59
Error: divergence detected in AMG solver: temperat Rubén FLUENT 3 December 11, 2007 12:48
user subroutine error CFDUSER CFX 2 December 9, 2006 07:31
user defined function cfduser CFX 0 April 29, 2006 10:58


All times are GMT -4. The time now is 02:13.