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

Backflow occuring at a pressure outlet?

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

Reply
 
LinkBack Thread Tools Display Modes
Old   August 12, 2004, 05:05
Default Backflow occuring at a pressure outlet?
  #1
Dave
Guest
 
Posts: n/a
Hi

I was wondering if anybody knew how I can stop backflow occuring at a pressure outlet? In my unsteady problem I have four ports that open one at a time and to simulate this I have a udf which changes the pressure at these pressure outlets. When a port is closed I set the pressure to be the same as the pressure inlet pressure as I do not know how to change the boundary condition to a wall. However, I get backflow from the "closed" ports which is completely messing up my results. How do I stop this from happening? Do I need to write a udf that changes the boundary condition from a pressure outlet to a wall and if so how do I do this?

Any help would be greatly appreciated. Dave
  Reply With Quote

Old   August 12, 2004, 17:39
Default Re: Backflow occuring at a pressure outlet?
  #2
Zhihua
Guest
 
Posts: n/a
I have never done simulations during which the boundary conditions are varied. I guess backflow appears because the interior pressure based on last calculation is lower than the inlet pressure in the flow direction. Seting the outlet pressure=inlet pressure means the outlet pressure is higher than the interior too. That's why backflow appears.
  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
Outlet pressure for compressible flow Michelle CFX 12 Today 18:38
UDF to adjust pressure outlet a.lynchy FLUENT 3 February 13, 2012 05:03
Using pressure outlet BC Shreyansh FLUENT 0 November 5, 2010 15:57
Gas pressure question Dan Moskal Main CFD Forum 0 October 24, 2002 22:02
Hydrostatic pressure in 2-phase flow modeling (CFX4.2) HB &DS CFX 0 January 9, 2000 14:19


All times are GMT -4. The time now is 23:43.