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

Passive Scalar boundary conditions

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   December 2, 2012, 08:41
Default Passive Scalar boundary conditions
  #1
New Member
 
Francesco
Join Date: Dec 2012
Posts: 3
Rep Power: 13
francesco12 is on a distinguished road
Hello,

I am performing a simulation of the advective-diffusive mass transfer for the oxygen in a fluid.
I have a bifurcating pipe (an artery and a vein), with a velocity inlet, a velocity outlet, and a pressure outlet as boundary conditions.
I'm using the passive scalar model to simulate the oxygen, and I would like to impose the normal concentration gradient, on the two outlets,
but since I'm using a velocity and a pressure as boundary conditions, I can only impose a specified value on those faces.
For what concerns the other boundaries, I have a concentration sink on the wall of the pipes (with a specified value of 0), and a constant concentration on the inlet.
I have also tried to use the flow-split condition, but sometimes the solution start diverging because of a recirculation on the cells of the boundary layer, even if I try extend the pipe to damp the recirculation.
The Schmidt number I'm using is quite high (2700), and I noticed that if I change the constant value on the outlets from 0 to 1 the solution for the passive scalar remains the same, on the other hand, imposing the gradient would be conceptually more correct.
Does anyone have any suggestion?

Thanks in advance,

Francesco
francesco12 is offline   Reply With Quote

Old   December 13, 2012, 04:15
Default
  #2
Senior Member
 
siara817's Avatar
 
siamak rahimi ardkapan
Join Date: Jul 2010
Location: Copenhagen, Denmark
Posts: 220
Rep Power: 18
siara817 is on a distinguished road
I hope I understood correct. If you want to have a normal distribution of a phase (oxygen) you can use lagrangian multiphase mode. Then the second phase will be defined as a normal distribution.
__________________
Good luck
Siamak
siara817 is offline   Reply With Quote

Reply

Tags
boundary condition, passive, scalar, schmidt, starccm+


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
Domain Imbalance HMR CFX 5 October 10, 2016 06:57
Impinging Jet Boundary Conditions Anindya Main CFD Forum 25 February 27, 2016 13:58
CFX13 Post Periodic interface EtaEta CFX 7 December 8, 2011 18:15
Update boundary conditions calculated by an external program CedricVH OpenFOAM 2 January 15, 2010 12:55
RPM in Wind Turbine Pankaj CFX 9 November 23, 2009 05:05


All times are GMT -4. The time now is 00:50.