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

semipermeable membrane

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

Reply
 
LinkBack Thread Tools Display Modes
Old   January 13, 2003, 09:37
Default semipermeable membrane
  #1
Roman
Guest
 
Posts: n/a
Dear all!

I want to simulate a module with a semipermeable membrane in CFX 5.5.1. I thought about using a thin surface but that is not porous/permeable. Ideally it should be fluid on the one side and gas on the other side. The membrane is permeable for two component of a tree component mixture. Has anybody an idea?

Thanks, Roman
  Reply With Quote

Old   January 13, 2003, 10:27
Default Re: semipermeable membrane
  #2
Mads Bang
Guest
 
Posts: n/a
To hinder passage of one fluid (scala equation) you simply set the a-coefficients to zero at the given boundary.

E.g. if you define your membrane domain as porous and at the interface to the free flow domain set the a-coefficients to zero (in fortran routine "userfds" in CFX4.3) I dont know how to access them in CFX 5.5. But at least you now got the principle.

Cheers, Mads
  Reply With Quote

Old   January 14, 2003, 09:44
Default Re: semipermeable membrane
  #3
Roman
Guest
 
Posts: n/a
Tanks, Mads

I fear the a-coefficients and the userfds don't exist in CFX 5.5.1. Anyway I don't know it and I can't find it. The user fortran subroutines which there are in CFX 4.3 don't exist in CFX 5.5. I suppose because of the many changes of the structure of CFX. Now the user can set all parameters in CFX Build or in the CCL-file so that own fortran subroutines are unusual.

Do you have a other idea?

Bye, Roman
  Reply With Quote

Old   January 14, 2003, 10:38
Default Re: semipermeable membrane
  #4
Mads Bang
Guest
 
Posts: n/a
Ok, if the a-coefficients are not accessible for the user (I certainly find that stupid!) then another option is to set the diffusivity of the specie to a very low value.

Generally speaking this is the most physical thing to do for many problems since there will nearly always be some crossover of your separated fluid.

However it will possible take longer to get a converged solution with this approach.

Cheers, Mads
  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
porous filtration membrane area in model catherina CFX 3 October 27, 2011 06:05
gas diffusion through membrane sosat1012 CFX 0 September 8, 2010 08:14
Membrane porous jump problem in VOF Hema kothimbare FLUENT 0 August 7, 2009 01:22
semipermeable membrane Muhammad Shakaib FLUENT 5 November 9, 2005 12:36
mass transfer from fluids to membrane Peter FLUENT 0 August 2, 2002 14:27


All times are GMT -4. The time now is 07:05.