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

Improving the CFD Case Imbalances

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   April 7, 2022, 05:43
Default Improving the CFD Case Imbalances
  #1
New Member
 
Join Date: Feb 2022
Posts: 5
Rep Power: 2
arv2995 is on a distinguished road
I have created a CFD Steady State Case and have run the case for 3000 iterations.

After the case was fully run, I checked the .res file in CFX Solver Manager to check the imbalances of the variables. I want to achieve imbalances below 10, if possible below 5.

But for a few variables, the imbalances are as high as 80(mainly the mass imbalance).
My question was, what are the methods I can use to achieve better imbalances in the next simulation for the same case? ( I want to keep the entire mesh constant).

Looking forward to your reply.
arv2995 is offline   Reply With Quote

Old   April 7, 2022, 06:10
Default
  #2
Senior Member
 
Gert-Jan
Join Date: Oct 2012
Location: Europe
Posts: 1,643
Rep Power: 25
Gert-Jan will become famous soon enough
In the solver manager, you need to create a plot in which you monitor all imbalances. Then you can see that the imbalances are not correct, so you need more iterations.
You can also see the imbalances at the bottom of the output file. There you'll probably get confirmed that the imbalances are not within your requirements.
To be on the safe side, you should specify 10000 iterations in Pre and add a convergence criteria of 0.01 for the Conservation target = 1%

BTW, better ask these CFX quesitons in the CFD forum

Also I can recommend to read this: https://www.cfd-online.com/Wiki/Ansy...ated_questions
Gert-Jan is offline   Reply With Quote

Old   April 7, 2022, 06:50
Default
  #3
New Member
 
Join Date: Feb 2022
Posts: 5
Rep Power: 2
arv2995 is on a distinguished road
Thank you for the reply.

I already checked the individual imbalances values. The problem is that the imbalances are reducing and increasing in a cyclic manner from -80 to + 80 for mass flow imbalance specifically speaking.

If I run the case again the same pattern is getting repeated unfortunately. Do you think any other change should be made , than running the case for more iterations. Like, will changing the physical timescale improve the imbalances?
arv2995 is offline   Reply With Quote

Old   April 7, 2022, 07:09
Default
  #4
Senior Member
 
Gert-Jan
Join Date: Oct 2012
Location: Europe
Posts: 1,643
Rep Power: 25
Gert-Jan will become famous soon enough
It can depend on anything. You need to give details on the case if you want more help.
Most likely, the solution is transient, so you need to do a transient calculation.
Gert-Jan is offline   Reply With Quote

Old   April 7, 2022, 07:29
Default
  #5
New Member
 
Join Date: Feb 2022
Posts: 5
Rep Power: 2
arv2995 is on a distinguished road
The solution is a steady-state model.

Also, what other points does this depends on? Also what details would you like to know?
arv2995 is offline   Reply With Quote

Old   April 13, 2022, 18:27
Default
  #6
Senior Member
 
Gert-Jan
Join Date: Oct 2012
Location: Europe
Posts: 1,643
Rep Power: 25
Gert-Jan will become famous soon enough
You can tell the software to look for a steady state solution.
But if there is no steady state solution, it will never find it, and your numerical solution will fluctuate for ever.
Gert-Jan is offline   Reply With Quote

Reply

Tags
ansys cfd and cfx, imbalances, solver manager, steady flow

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
Artificial Intelligence in CFD Naresh yathuru Main CFD Forum 71 March 30, 2021 00:32
Future CFD Research Jas Main CFD Forum 10 March 30, 2013 13:26
CFD Post Case Comparison akarlin CFX 0 March 3, 2013 21:52
Need help on simple CFD case. (using CFD-ACE+) Sean Main CFD Forum 1 September 30, 2005 11:05
Which is better to develop in-house CFD code or to buy a available CFD package. Tareq Al-shaalan Main CFD Forum 10 June 13, 1999 00:27


All times are GMT -4. The time now is 19:49.