CFD Online Logo CFD Online URL
Home > Forums > CFX

About the zero eqration mode of transition in CFX

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

LinkBack Thread Tools Display Modes
Old   April 10, 2008, 11:00
Default About the zero eqration mode of transition in CFX
Posts: n/a
Hi,everyone. Has anyone used the zero equation model of transition in CFX before? According to the 'ANSYS CFX-Solver Modeling Guide', one can prescribe laminar zones at the leading edges of the wings by setting the intermittency to 0(laminar) or 1(turbulent) over different regions. So what I want to ask is, should I need to write a Fortran routine to setting the intermittency over different regions? Or I can do it with the CEL expressions in CFX? And should I set the intermittency over the whole compute domain,or just near the wall?
  Reply With Quote

Old   April 10, 2008, 13:04
Default Re: About the zero eqration mode of transition in
Posts: n/a
Hi leo1985,

You only need to set it at the wall. If you have geometric regions which delineate the laminar and turbulent parts, you should be able to specify the intermittency directly by inputting a value on boundary conditions associated with each.

If you don't have grid regions, you can do it with a CEL expression. If the geomtry is simple, a step function or linear interpolation function may do, but if it is complex, I would recommend going back to your CAD model or mesh and creating the appropriate regions.

Note that you can also create new regions on your mesh in CFX-Pre, which would allow you to visually pick the areas that are laminar vs. turbulent.

  Reply With Quote

Old   April 11, 2008, 10:29
Default Re: About the zero eqration mode of transition in
Posts: n/a
Thank you very much , CycLone. Now comes the new problem. I just try to set the intermittency on a plane wall, when solving the flow over a plane wall. I use the zero equation mode of transition, and set the intermittency to 0 on one part of the wall and 1 on the other part of the wall by user function (by choosing user function->interpolation->three dimensional->import data from file).The latter part is located downstream of the former part. However, when I see the Turbulence intermittency distribution at the wall in the CFX-post, it doesn't like what I have set them to be. Actually, I think I didn't set the transition position successfully. Why? By the way, are there any examples available showing how to set the transition mode? I have spent so much time on it, God.
  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
Compressible Flow in Ansys CFX bcheruk CFX 15 July 6, 2017 06:30
the intermittency in the CFX transition model leo1985 CFX 0 June 14, 2008 12:13
How to specify the mesh moving mode in CFX Jemy CFX 2 August 27, 2007 20:04
Meshing-only mode in CFX ? Nena CFX 0 August 10, 2007 05:03
CFX 4.4 installation problem Pandu Sattvika CFX 1 December 1, 2001 05:07

All times are GMT -4. The time now is 05:19.