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

Opening BC for multiphase problem

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

Reply
 
LinkBack Thread Tools Display Modes
Old   October 25, 2005, 11:06
Default Opening BC for multiphase problem
  #1
John
Guest
 
Posts: n/a
Hi, all

Does someone have expeience of defining an opening BC for a gas-liquid phase problem? It seems that I need to input both gas liquid velocities. However I do not know that.

Please give some comments, Thanks!

Best regards!

John
  Reply With Quote

Old   October 25, 2005, 11:22
Default Re: Opening BC for multiphase problem
  #2
Rui
Guest
 
Posts: n/a
Hi,

Whether it's a multi-phase or a single-phase problem, on an Opening BC you may input the pressure instead of velocity.

Take a look at the Documentation, Solver Modelling - Boundary Condition Modelling - Opening, and Solver Theory - Basic Solver Capability Theory - Boundary Conditions - Opening

Regards,

Rui
  Reply With Quote

Old   October 25, 2005, 11:37
Default Re: Opening BC for multiphase problem
  #3
John
Guest
 
Posts: n/a
Hi, Rui

Thanks for your reply.

Yes, I can choose to input pressure, however in that case I need to input volume fractions of gas and liquid as well. I also need to know the values of the additional variables at opening location, which I do not know.

Thanks!

John

  Reply With Quote

Old   October 25, 2005, 12:46
Default Re: Opening BC for multiphase problem
  #4
Rui
Guest
 
Posts: n/a
Hi,

The volume fractions and the additional variables values at the Opening BC will only be used for flow into the domain.

If in your Opening BC there is actually flow into the domain, you have to know the volume fractions and the additional variables values that are flowing into your domain.

But there's another option which isn't mentioned in the Documentation, and which you may only be set editing the .ccl file: BOUNDARY : out
Boundary Type = OPENING
Location = out
BOUNDARY CONDITIONS :
MASS AND MOMENTUM :
Option = <font color="red">Extrapolation</font>
END
END
END




However, this was told to me by the CFX support: "Note that this type of treatment of the b.c. should not be used for a steady state case, as it is not constrained enough"I never used this type of definition, so I don't know if it works well or not.

Regards,

Rui
  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
Problem Importing Geometry ProE to CFX fatb0y CFX 3 January 14, 2012 20:42
Can I solve this problem by Fluent? Kai_kc FLUENT 1 October 27, 2010 05:29
problem opening case and data in fluent Adam FLUENT 1 February 15, 2007 17:53
Opening Andrew CFX 4 April 20, 2006 14:00
problem in opening CFX-pre and CFX-post 10.0 eka CFX 0 April 14, 2006 14:47


All times are GMT -4. The time now is 05:20.