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

why did the message always come out?

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   June 25, 2003, 18:49
Default why did the message always come out?
  #1
Lee
Guest
 
Posts: n/a
When I run a roundpipe model(which is a semi-circe,at one end of the pipe the bounday type is inlet,the other end is outlet,and there is a symmetry boundary),I set the outlet boundary as the prescribed flow split(fs=1),but the information file always shows one warning message:

*** WARNING #001 *** FLUID INFLOW DETECTED AT SOME OUTFLOW BOUNDARIES WHERE MASS FLUXES ARE FORCED TO ZERO.

IF THIS CONDITION PERSISTS, YOUR RESULTS MIGHT BE WRONG

THE OUTFLOW BOUNDARY MIGHT NOT BE WELL SPECIFIED OR THE GRID MIGHT BE TOO COARSE NEAR THE OUTFLOW BOUNDARY

but I think I the meshs created are enough fine,so what is the reason to cause this warning message?

Thank you very much for your help!

Best Regards, Lee

  Reply With Quote

Old   June 26, 2003, 07:37
Default Re: why did the message always come out?
  #2
4xF
Guest
 
Posts: n/a
You get back flow at the outlet boundary. Solution: Use a pressure boundary instead.
  Reply With Quote

Old   June 26, 2003, 08:24
Default Re: why did the message always come out?
  #3
Lee
Guest
 
Posts: n/a
First,thank you very much! Second,I just want to know why the warning message always comes out and what is the proble reason to cause the problem.

I think if the model simply like this one can't be modeled by the inlet and outlet boundary type(note,the inlet flow velocity is 50+20*sin(time),and diameter is 38 milimeters),how can the star-cd model the other complex models?

So I really want to know where the problem is.

Thanks a lot for who can help me out this problem!

lee

  Reply With Quote

Old   June 27, 2003, 04:48
Default Re: why did the message always come out?
  #4
marco
Guest
 
Posts: n/a
Hallo!

If you are doing a subsonic transient calculation you shouldn't use 'OUTLET' but 'PRESSURE'. Look at the methodology manual, page 5-5.

Marco
  Reply With Quote

Old   June 28, 2003, 09:58
Default Re: why did the message always come out?
  #5
4xF
Guest
 
Posts: n/a
Small hint: Flow is unsteady with an unsteady boundary layer. So, it is most likely that you get back flow at the outlet and therefore a pressure boundary condition has to be applied instead of an outlet BC.
  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
I got "Error Message" Young CFX 0 April 25, 2008 13:00
Error message mbouda FLUENT 0 July 16, 2007 04:45
What is this message? David Baker Siemens 0 March 14, 2006 01:02
Error message Luc FLUENT 1 December 12, 2002 14:22
What does this message mean? Marc FLUENT 0 November 14, 2001 12:45


All times are GMT -4. The time now is 15:25.