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

suggest solution for reverse flow

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

Reply
 
LinkBack Thread Tools Display Modes
Old   January 23, 2012, 02:20
Default suggest solution for reverse flow
  #1
New Member
 
alimoddin
Join Date: Jan 2012
Posts: 1
Rep Power: 0
alimoddin is on a distinguished road
Hi Users

i am working on CFD analysis of thermocompressor which comprises two inlet steams pressure at 10 bar and 1.5 bar and output pressure is 3.5 bar.For meshing i used ICEM software and postprocessing is done in FLUENT.
i used unstructured volume meshing,quality of which is more than 0.3 which is sufficient. continuity value i took as 1e-6,after run given solution converges ,used k Epsilon model,
Initially i kept energy equations OFF.
After various RUN , i am getting reverse flow .
please give me suitable suggestion to eliminate reverse flow.or else suggest me suitable alternating model.
please reply fast.
Thanking YOU.
alimoddin is offline   Reply With Quote

Old   January 23, 2012, 14:14
Default
  #2
Senior Member
 
Join Date: Jun 2011
Posts: 108
Rep Power: 6
mali28 is on a distinguished road
Quote:
Originally Posted by alimoddin View Post
Hi Users

i am working on CFD analysis of thermocompressor which comprises two inlet steams pressure at 10 bar and 1.5 bar and output pressure is 3.5 bar.For meshing i used ICEM software and postprocessing is done in FLUENT.
i used unstructured volume meshing,quality of which is more than 0.3 which is sufficient. continuity value i took as 1e-6,after run given solution converges ,used k Epsilon model,
Initially i kept energy equations OFF.
After various RUN , i am getting reverse flow .
please give me suitable suggestion to eliminate reverse flow.or else suggest me suitable alternating model.
please reply fast.
Thanking YOU.

What are your boundary conditions?
mali28 is offline   Reply With Quote

Old   January 23, 2012, 14:59
Default
  #3
Senior Member
 
Real Name :)
Join Date: Jan 2010
Location: United States
Posts: 180
Rep Power: 7
ComputerGuy is on a distinguished road
While I don't know what your geometry or boundary conditions are, reversed flow is usually reported when an outlet (i.e., the one at 3.5 bar) begins drawing mass into the system. This seems like a reasonable condition, given that your "inlet" has a lower pressure than the outlet. I don't know about thermocompressors, but just ensure that the boundary conditions you've imposed (along with system dynamics/gravity/etc) wouldn't actually cause reversed flow.

Another thing to check: often, in flows with heavy swirl or pulsation, a few of the cells on an outlet will have some degree of backflow. This is consistent with "real life" and isn't really anything to be worried about. Thus:
1) Compare the number of faces which have reported backflow to the number of faces on the outlet
2) Assess whether the flow has pulsation

If 1 is small and 2 is a "yes" or a "maybe," then I wouldn't be worried. Additionally, often times the error resolves itself as the system reaches a natural steady state, as opposed to the initial guess you provided.

ComputerGuy

Quote:
Originally Posted by alimoddin View Post
Hi Users

i am working on CFD analysis of thermocompressor which comprises two inlet steams pressure at 10 bar and 1.5 bar and output pressure is 3.5 bar.For meshing i used ICEM software and postprocessing is done in FLUENT.
i used unstructured volume meshing,quality of which is more than 0.3 which is sufficient. continuity value i took as 1e-6,after run given solution converges ,used k Epsilon model,
Initially i kept energy equations OFF.
After various RUN , i am getting reverse flow .
please give me suitable suggestion to eliminate reverse flow.or else suggest me suitable alternating model.
please reply fast.
Thanking YOU.
ComputerGuy 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
Accuracy and convergence pawan1989 FLUENT 5 April 15, 2010 17:17
Strange Solution for a simple pipe flow!! shekharc Main CFD Forum 4 May 9, 2005 09:21
about Reacting Flow with solution knight FLUENT 4 July 18, 2001 10:26
Discussion about Mesh independant solution Seb Main CFD Forum 13 May 22, 2001 13:37
CFX 4 for two continuous fluid flow solution sinjae CFX 1 May 19, 2001 03:07


All times are GMT -4. The time now is 22:24.