CFD Online Logo CFD Online URL
Home > Forums > CFX

Convergence of an Annular Jet Model

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

LinkBack Thread Tools Display Modes
Old   February 28, 2007, 06:38
Default Convergence of an Annular Jet Model
Posts: n/a
Hello I am a final year university student and am trying to model an annular jet flow expanding into a cylindrical downstream expansion chamber using CFX. The boundary conditions in the expansion chamber are specified as 'Opening' to permit jet entrainment. I am currently having problems getting the solution to convergene (the radial and tangential momemtum eqns) when I make the mesh finer (I am using a structured mesh produced in ICEM). Also the model is a 30 deg wedge segment with periodic boundaries.

As CFX had no under-relaxation factor I have tried changing the Timestep between 10e-3 and 10e-5 in the Solver Options but to no avail. Does anyone have any suggestions? Thanks in advance Richard
  Reply With Quote

Old   February 28, 2007, 17:21
Default Re: Convergence of an Annular Jet Model
Glenn Horrocks
Posts: n/a

What Reynolds number? What mesh resolution are you using? What turbulence model? How far downstream is your exit? Compressible or incompressible? Need more details.

And forget about under-relaxation factors. That's from the old days with uncoupled solvers and is very rarely used with CFX these days.

Glenn Horrocks
  Reply With Quote

Old   March 1, 2007, 12:59
Default Re: Convergence of an Annular Jet Model
Posts: n/a
Thank you Glenn for your response, I stopped playing with under-relaxation factors and instead realised from your further questions that my solution domain was rather small and this was the problem. I have since increased it and found that it now convergenes. Thanks again
  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
Convergence Centurion2011 FLUENT 26 November 24, 2015 15:46
about Subgrid-scale model impecca OpenFOAM Running, Solving & CFD 4 December 20, 2013 11:36
Heat Transfer convergence Problem mit a 1/6 compressor model chili023 CFX 1 January 15, 2011 07:41
Convergence problems with SSG turbulence model Ram CFX 1 June 19, 2006 10:08
convergence problem with FLUENT cavitation model Belete Kiflie FLUENT 3 February 20, 2006 11:16

All times are GMT -4. The time now is 02:26.