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

If the gas flows out of the inlet boundary,...

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   November 1, 2002, 06:08
Default If the gas flows out of the inlet boundary,...
  #1
Miles
Guest
 
Posts: n/a
I'm doing some transient analysis of pipes. If the gas escape from the inlet boundary,what will happen? Can Star-CD deal with this kind problem?
  Reply With Quote

Old   November 1, 2002, 06:39
Default Re: If the gas flows out of the inlet boundary,...
  #2
Joern Beilke
Guest
 
Posts: n/a
If you have outflow you can use inlet or pressure boundary conditions.
  Reply With Quote

Old   November 1, 2002, 06:43
Default Re: If the gas flows out of the inlet boundary,...
  #3
Miles
Guest
 
Posts: n/a
I've used inlet boundary conditions.It seems that Star-cd hasn't processed the problem.
  Reply With Quote

Old   November 1, 2002, 08:20
Default Re: If the gas flows out of the inlet boundary,...
  #4
guang ai
Guest
 
Posts: n/a
Hi Miles, since upwind scheme has been used, inlet boundary as i see could not handle reverse flow. why not extrude the inlet for a distance.
  Reply With Quote

Old   November 1, 2002, 09:25
Default Re: If the gas flows out of the inlet boundary,...
  #5
Anders
Guest
 
Posts: n/a
If you mean that you INTEND to use a velocity inlet as outlet boundary (i.e. apply a negative inlet flow - like a suction point) it should be alright. That is if you put a pressure boundary where the flow should enter, to be able to specify turbulent quantities.
  Reply With Quote

Old   November 6, 2002, 16:14
Default Re: If the gas flows out of the inlet boundary,...
  #6
Miles
Guest
 
Posts: n/a
It seems that Star-CD cannot deal with this problem.
  Reply With Quote

Old   November 7, 2002, 06:33
Default Re: If the gas flows out of the inlet boundary,...
  #7
Joern Beilke
Guest
 
Posts: n/a
It seems to me that you are not able to describe your problem in a way that we know what you are doing and what you intend to do.

  Reply With Quote

Old   November 7, 2002, 08:48
Default Re: If the gas flows out of the inlet boundary,...
  #8
deloubie
Guest
 
Posts: n/a
I'm sorry. I'm trying to simulate the gas flow through pipes. And the boundary conditions is that the flow of the inlet boundary can be positive and negative.
  Reply With Quote

Old   November 7, 2002, 12:26
Default Re: If the gas flows out of the inlet boundary,...
  #9
Joern Beilke
Guest
 
Posts: n/a
You have about 3 possibilities to do this.

1.) use a user defined subroutine and describe the velocity as a function of time

2) use a table with the values of the velocity

3) use the transient calculation with different load steps. For each load step you can select you boundary values and ramp between them.

If you have an analytical function for the vel vs. time the subroutine should be the most straightforward way to go. Otherwise use the second or third way.

  Reply With Quote

Old   November 7, 2002, 14:07
Default Re: If the gas flows out of the inlet boundary,...
  #10
Miles
Guest
 
Posts: n/a
I'll use the first method. Thank you very much.
  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
Pressure inlet boundary conditions for open channel flows jack2000 OpenFOAM Running, Solving & CFD 5 December 6, 2018 11:00
Inlet turbulent boundary condition: external flows ROOZBEH FLUENT 3 August 28, 2015 15:34
Inlet turbulent boundary condition, external flows ROOZBEH Main CFD Forum 1 February 6, 2009 12:37
Non-matched Boundary Flows Roger CFX 7 April 6, 2006 07:27
length scales at inlet for internal flows Anne-Marie Giroux Main CFD Forum 3 July 5, 1999 21:28


All times are GMT -4. The time now is 13:18.