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

doubt in post processing

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   December 3, 2011, 00:45
Default doubt in post processing
  #1
New Member
 
murugesan
Join Date: Aug 2011
Posts: 8
Rep Power: 14
murugesanjeyabalan is on a distinguished road
Hi,
I have a small question: during iterations I get the warning message "reversed flow in xxxx faces on pressure outlet". The number xxxx goes down with iterations. then the solution converges and there are still about 1000 faces in the outlet with reversed flow. If I continue the iterations the number keeps falling, and probably it will reach zero (no more warnings). What does this mean? Is the solution not really converged when FLUENT says so
(according to the default residuals criteria)? IS the solution converged when finally there are no more faces with reversed flow or when this number stays constant?
thanks
murugesanjeyabalan is offline   Reply With Quote

Old   December 3, 2011, 04:18
Default Hi
  #2
Senior Member
 
shoeb khan
Join Date: Nov 2011
Posts: 179
Rep Power: 14
shk12345 is on a distinguished road
Hi
may be i am wrong, but according to me
Many times there is a reverse flow problem at the starting of the simulation.
But as we proceed, the reverse flow problem vanishes and it doesn't comes back after a quite a long spam of iteration then surely i can say that the solution is converged.

Correct me if i am wrong please.

SHK
shk12345 is offline   Reply With Quote

Old   December 3, 2011, 07:10
Default
  #3
New Member
 
kamran
Join Date: Apr 2011
Posts: 17
Rep Power: 14
mashinsazi is on a distinguished road
In every turbulent model we have some large eddies which may bring about Reversed Flow.That's something normal.
mashinsazi is offline   Reply With Quote

Old   December 3, 2011, 13:56
Default
  #4
Senior Member
 
shoeb khan
Join Date: Nov 2011
Posts: 179
Rep Power: 14
shk12345 is on a distinguished road
No turbulence models doesn't create reverse flows
it just depend on ur geometries

u can switch on turbulence models when ur solution is converged
hope that will help u

shk
shk12345 is offline   Reply With Quote

Old   December 4, 2011, 02:47
Default
  #5
New Member
 
kamran
Join Date: Apr 2011
Posts: 17
Rep Power: 14
mashinsazi is on a distinguished road
Model and geometry are both important.
mashinsazi is offline   Reply With Quote

Old   December 13, 2011, 03:13
Default
  #6
Member
 
Join Date: Mar 2009
Posts: 41
Rep Power: 17
mehulkumar is on a distinguished road
Hi,

According to my understanding, criterion for solution convergence and reverse flow are two different things.

You can always check your solution is converged OR not by simulating for higher criterion of solution convergence.

You can adjust related parameters in pressure-outlet BC if reverse flow is occurring and it is not desirable!

Mehulkumar
mehulkumar is offline   Reply With Quote

Reply

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
Ansys Post processing ano999 ANSYS 1 May 27, 2011 17:24
NO model vs post processing in coal combustion,CFX sakalido CFX 1 April 15, 2011 15:07
post processing for KIVA dirga Main CFD Forum 5 April 23, 2009 11:58
Post Processing in FEM Abhijit Tilak Main CFD Forum 0 April 26, 2004 12:59
post processing in CFD MANISH BHARGAVA Main CFD Forum 0 October 17, 1998 21:51


All times are GMT -4. The time now is 13:01.