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

Round jet model in FLUENT

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

Reply
 
LinkBack Thread Tools Display Modes
Old   April 8, 2009, 14:10
Default Round jet model in FLUENT
  #1
New Member
 
Andrew
Join Date: Apr 2009
Posts: 5
Rep Power: 7
PurdueME is on a distinguished road
I'm trying to do a turbulent analysis of a simple round jet in Fluent 6.3 and am struggling to get a correct solution. I have tried everything I can think of with no success. The "best" settings I have found so far are below, but I still don't get a self-similar solution.

My control volume looks like this:
----------------
| |
|------| |
|------| |
| |
|--------------|

The top boundary is set to outflow (I'm using incompressible flow.)
The right boundary is set to outflow.
The bottom boundary is set to an axis (jet centerline).
The left-bottom boundary is set to a velocity inlet (velocity specified such that Re ~ 5000).
The left-top boundary is set to outflow.
The left-middle boundary and all internal boundaries are set to wall (jet wall).

I'm trying to compare the S-A, k-eps, and k-w equations with default constants (none give me a correct solution).
Second-order solvers for pressure and momentum.
SIMPLE solver for pressure-velocity coupling.

My grid is spaced such that I have 20 grid points along the jet radius.
Control volume extends 20 diameters downstream of jet exit and 5 diameters above jet wall.

Any other settings are default.

Any ideas? This is my first real Fluent project, so maybe there's something obvious I'm missing.
PurdueME is offline   Reply With Quote

Old   April 8, 2009, 14:59
Default
  #2
Member
 
Newton KF
Join Date: Mar 2009
Posts: 36
Rep Power: 7
NewtonKF is on a distinguished road
Have you tried to turn some of the outflows conditions to wall condition??? Some numerical problem may occur if you use outflow condition in the left-top region, due to recirculation in this zone... Are you trying to correlate those results to some specific paper??? If not, i recommend the paper of Hussain: Velocity measurements in a high-Reynolds-number, momentum-conserving, axisymmetric, turbulent jet...
Good luck...
NewtonKF is offline   Reply With Quote

Old   April 8, 2009, 16:41
Default
  #3
Senior Member
 
Andrew
Join Date: Mar 2009
Location: Washington, DC
Posts: 193
Rep Power: 7
mettler is on a distinguished road
are you getting an answer at all? This is basically just a flow problem, correct? If you plot the residuals you can see if it is diverging or flat-lining. What is your overall grid count? I would try to mesh it a little finer and see what happens. I do agree with the above post about treating the right upper bc as a wall first. I believe you can post pics on here, so a gambit screen shot might help out too.
mettler is offline   Reply With Quote

Reply

Tags
fluent, round jet, turbulent

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
FLUENT cavitation model CFDtoy FLUENT 4 October 15, 2008 10:31
Aspect Ratio of 2D model in FLUENT Francis FLUENT 1 July 25, 2008 22:09
Reynolds Stress Model in Fluent Vs CFX Tim FLUENT 0 December 6, 2005 22:03
Mixing length models and zero-hvac model in fluent sarah_ron FLUENT 0 November 27, 2004 23:29
how to model a free jet in gambit Dr.V.Ilangovan FLUENT 1 November 15, 2004 17:45


All times are GMT -4. The time now is 01:17.