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

scalar flux boundary condition

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

Reply
 
LinkBack Thread Tools Display Modes
Old   May 21, 2003, 21:56
Default scalar flux boundary condition
  #1
Murali
Guest
 
Posts: n/a
<font face = "arial">Does anybody know how to specify the following boundary condition ?


dq
flux = -D---- = q^0.5
dx



where q is a user-defined scalar. Any idea which user-subroutine is to be used and how ?

</font>
  Reply With Quote

Old   May 22, 2003, 07:49
Default Re: scalar flux boundary condition
  #2
John
Guest
 
Posts: n/a
Define the wall region where you want to specify the species flux as constant flux region and use user code bcdefw to change the flux according to solution.
  Reply With Quote

Old   May 22, 2003, 14:18
Default Re: scalar flux boundary condition
  #3
Murali
Guest
 
Posts: n/a
<font face = "arial">Hello John,

nice suggn. Thanx. The subroutine BCDEFW requires me to RETURN the value of SCALAR(IS). Are you suggesting that if I have the previous boundary condition, I specify a constant flux say A close to te value of q^0.5 ? i.e.
dq
flux = -D---- = q^0.5 = approx A where A is a constant
dx


So if I specify A as the constant flux, I would then correct it to the required flux using a finite difference expression, involving the values at the centre of the adjacent cell and value at wall ??? i.e.Since,
SCALC(IS) - SCALAR(IS)
flux = -D ---------------------
deltax


does that mean,

SCALAR(IS) = SCALC(IS)+flux*deltax/D ? Are you suggesting I iterate on this value locally ?

Regards
Murali

http://groups.yahoo.com/group/fuel_cells/
</font>
  Reply With Quote

Old   May 23, 2003, 06:28
Default Re: scalar flux boundary condition
  #4
John
Guest
 
Posts: n/a
Since you already know A, just put A in whichever scalar, say:

IF(IREG.EQ.1) THEN scalar(1)=a endif

SEE nom.inc file in ufile directory because for BCDEFW, scalar is either mass fraction or its flux depending on what boundary condition you specified in prostar.
  Reply With Quote

Old   May 23, 2003, 11:50
Default Re: scalar flux boundary condition
  #5
Murali
Guest
 
Posts: n/a
John,

wonderful. thanx a lot.

Regards Murali
  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
User defined scalar boundary condition Philip FLUENT 1 December 4, 2013 11:23
How do I set scalar boundary condition? D.K lLee CD-adapco 1 December 5, 2012 14:24
what specified flux mean in boundary condition? lucy FLUENT 0 January 5, 2009 05:13
Scalar boundary condition inside the fluid domain Ethan CD-adapco 3 May 2, 2007 16:02
zero flux boundary for diffusion scalar cmv CD-adapco 1 April 15, 2005 05:42


All times are GMT -4. The time now is 10:13.