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

Preventing backflow from occuring

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

Like Tree1Likes
  • 1 Post By ThomasZiegenhein

Reply
 
LinkBack Thread Tools Display Modes
Old   March 3, 2012, 10:57
Question Preventing backflow from occuring
  #1
New Member
 
BButler
Join Date: Jan 2012
Posts: 3
Rep Power: 5
bb21 is on a distinguished road
Im am working on a horizontal pipe resembling part of the lungs bronchioles. Instead of working with a pressure difference (between the inlet and outlet) I am focusing on volumetric flow rates therefore I am using a velocity inlet and a flow split outlet.
I am entering velocities using a time table as it is time dependent, air is entering the tube at a certain velocity for a certain time period. Then when the time is reached the velocity drops to 0 m/s and air no longer enters the tube.

The problem is that when the velocity drops to zero m/s the air starts to flow backwards, this does not occur in the body.
Is there anyway of entering a function or table to ensure the air flows out the tube once the velocity drops to 0m/s
I want to work like an on/off switch

Any help would be greatly appreciated
bb21 is offline   Reply With Quote

Old   March 3, 2012, 11:19
Default
  #2
New Member
 
Thomas Ziegenhein
Join Date: Feb 2012
Posts: 8
Rep Power: 5
ThomasZiegenhein is on a distinguished road
you don't give the pressure difference at the pressure outlet, the pressure is depending on the wall shear stress (in a pipe). So use pressure outlet and you don't have problems with backflow. Because of continuity i think you can not deactivate the backflow.

Greetings Thomas
siara817 likes this.
ThomasZiegenhein 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
Modeling Backflow for a 3D Airfoil (Wing of Finite Span) Josh CFX 9 August 18, 2009 11:31
backflow temperature specification jonglee FLUENT 0 April 20, 2007 04:57
Problem with integrals and averages if backflow?? Amit FLUENT 0 October 19, 2006 18:54
Backflow occuring at a pressure outlet? Dave FLUENT 1 August 12, 2004 17:39
Swirl in backflow on pressure outlets Jonas Larsson FLUENT 17 February 3, 2000 03:14


All times are GMT -4. The time now is 02:20.