CFD Online Logo CFD Online URL
Home > Forums > Main CFD Forum


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

LinkBack Thread Tools Display Modes
Old   November 11, 1999, 08:30
Default AXIS BOUNDARY-CONDITION in Dispersed Phase Flow
Remesh K
Posts: n/a
Dear friends,

I am simulating dispersed flow using Fluent V 4.32. I have a problem with axis boundary condition. I set the CELL-TYPE of centre line of the Nozzle as the AXIS. But in SETUP-2 LIST-BOUNDARY the boundary condition is seen to be taken as SYMMETRY REFLECT and the particle found to reflect on hitting the AXIS. But this is undesirable and the particles should pass through as if in the LIVE cell. How to change the BOUNDARY-CONDITION of AXIS to a suitable one, so that the particles will pass through?

Could anyone help me? Your help will be greatly appreciated.


  Reply With Quote

Old   November 11, 1999, 11:34
Default Re: AXIS BOUNDARY-CONDITION in Dispersed Phase Flow
John C. Chien
Posts: n/a
(1). I think, the axis is only related to the coordinate system, the flow does not know whether there is an axis or not. (2). I would say that it is a 3-D problem. In the 3-D problem, there is no boundary condition at the axis.
  Reply With Quote

Old   November 11, 1999, 21:03
Default Re: AXIS BOUNDARY-CONDITION in Dispersed Phase Flow
Jin Wook LEE
Posts: n/a
Mathematically, axis does not have any volume, and it is treated similarly as 'symmetry line in 2D case'. So, I think that there is no way(I am not quite sure) except to impose symmetry reflect boundary condition'. I think that it is perfect for 2D case(in Fluent, symmetry cells), and it might be fairly O.K. to use default 'symmetry reflect' if you have enough cells near the axis for 3D case. After reflecting small distance, it will proceed to its own way. There might be small error.

If you really want to impose passing condition, you should not generate your grid system by polar(or cylindrical) coordinates. Instead, you should generate grid system by BFC or UNS based on Cartesian coordinates, then there is finite volume cells at the axis. Then your axis is consist of live cells with finite volume, not any more boundary cells, and particle does pass the axis.

Sincerely, Jinwook
  Reply With Quote

Old   November 16, 1999, 23:44
Default Re: AXIS BOUNDARY-CONDITION in Dispersed Phase Flow
Guosheng Kang
Posts: n/a
I guess you forgot to change the boundary type when you set the boundary, Change it from "symmetry" type to "axis" type, it will work. By the way, the inlet direction should be in x-direction. Hope this is not too late.

  Reply With Quote


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
Volume of Flow Rate (VFR) boundary condition therockyy FLOW-3D 0 May 23, 2011 14:19
External Radiation Boundary Condition (Two sided wall), Grid Interface CFD XUE FLUENT 0 July 8, 2010 06:49
Mass flow boundary condition Renato. Main CFD Forum 0 July 21, 2006 22:07
compressible two phase flow in CFX4.4 youngan CFX 0 July 1, 2003 23:32
Problem on boundry of two phase flow youngan CFX 0 June 30, 2003 02:32

All times are GMT -4. The time now is 11:52.