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

Periodically occuring reverse flow after residuals have converged

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   October 29, 2014, 10:47
Default Periodically occuring reverse flow after residuals have converged
  #1
New Member
 
zack
Join Date: Oct 2014
Posts: 13
Rep Power: 11
zackufairu is on a distinguished road
Greetings CFD users
I have found an interesting problem on a tutorial on electronics cooling by forced convection

https://confluence.cornell.edu/displ...lectronics+Box

As mentioned I have used velocity inlet and pressure outlet.

The graph of residuals for momentum and continuity will become a straight zero slope line.So naturally people will assume convergence and stop the iterations.
However after every 100 or so iterations after that,there will be continous messages of reversed flow at pressure outlet for the next 20 iterations
After this the number of reverse flow iterations steps will increase to the point that all steps show reverse flow.
and finally divergence also occurs.

This is true even if velocity at inlet is increased substansially.
Thus no matter how many times this process is done there will be this same pattern repeated.

In such a case can I trust the results have converged?If not what things do I need to change?
Also being a physics student could someone tell me why this "repeating"reverse flow occurs ?
Thank you
zackufairu is offline   Reply With Quote

Old   October 29, 2014, 17:59
Default
  #2
New Member
 
zack
Join Date: Oct 2014
Posts: 13
Rep Power: 11
zackufairu is on a distinguished road
Why is no one answering is the problem not well explained?
zackufairu is offline   Reply With Quote

Reply

Tags
convection dominated, convergence fluent, convergence issues, reverse 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
About Some Concepts:Laminar flow, turbulent flow, steady flow and time-dependent flow Jing Main CFD Forum 8 October 5, 2018 18:02
Review: Reversed flow CRT FLUENT 1 May 7, 2018 06:36
Reverse flow warning and solution divergence SH_P FLUENT 0 May 27, 2012 16:26
Reverse Flow Problem. (Hull with a Bulbous Bow )Towing Tank simulation. Nyarla Siemens 2 March 13, 2012 20:04
flow field residuals into posdat? nicola Siemens 0 February 9, 2007 11:54


All times are GMT -4. The time now is 09:54.