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

Injections

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

Reply
 
LinkBack Thread Tools Display Modes
Old   August 26, 2002, 05:07
Default Injections
  #1
Atholl
Guest
 
Posts: n/a
Hi all,

I've defined an injection (i.e. particle density, diameter and position in my geometry) using previously converged case & data files of horizontal two-phase flow in an annulus. After some preliminary sessions of playing around with the settings, I've found a couple of problems:

1) My geometry length is around 6m, but no matter what settings I seem to alter, the particle track terminates around half of the length. What's wrong here?

2) When I alter the particle diameter, small diameters (c. 0.0001m) show the particle staying around the low side of the annulus (where it was defined initially). However, if I change the diamter to something larger (i.e. 0.1m) the track shows the particle being lifted up from the low side to the top side. Obviously, the larger the particle, the less likely it is to be lifted or dragged along by the fluid, so why am I getting this contradictory result?

Thanks in advance,

Atholl
  Reply With Quote

Old   August 26, 2002, 14:07
Default Re: Injections
  #2
Shiping Liu
Guest
 
Posts: n/a
For the question 1,I think you might set a too small step number or too short time.
  Reply With Quote

Old   August 27, 2002, 03:54
Default Re: Injections
  #3
Atholl
Guest
 
Posts: n/a
Yes, you are right: I altered some of these settings and it fixed the problem. Thankyou!

Has anyone had any experience with defining injections? I want to find out if a spherical particle of a certain diameter and density will be moved by the prevailing flow field. Is the injection method the correct way to go about this?

I know if the fluid velocity is insufficient, the particle will not move. At higher velocities, the particle may roll, slide or bounce along, and at even higher velocities, the particle will be lifted up into suspension. Can Injections give me this information?

Thanks again in advance

Atholl
  Reply With Quote

Old   August 27, 2002, 10:38
Default Re: Injections
  #4
xjrocket
Guest
 
Posts: n/a
Maybe u would try to calculate Saffman Lift Force.
  Reply With Quote

Reply

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
Defining DPM Particle Injections with a UDF TedBrogan FLUENT 0 April 18, 2011 16:45
Coal Injections problem Carlo FLUENT 0 September 30, 2009 06:15
DPM injection ritmat FLUENT 6 June 26, 2007 02:38
injections Donia FLUENT 4 June 2, 2007 06:40
How to define injections in DPM model lingo FLUENT 5 December 16, 2003 11:22


All times are GMT -4. The time now is 07:55.