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

Particles not been tracked

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   March 15, 2013, 14:04
Default Particles not been tracked
  #1
New Member
 
Mack Johnson
Join Date: Mar 2013
Posts: 1
Rep Power: 0
mack_johnson is on a distinguished road
Hi,

I am trying to simulate a human head being sneezed on. My particle inlet is set 0.5m away from the human mouth, with a 20m/s velocity. The partilce injection is a surface injection. the max number of steps is set at 10,000,000. I have meshed the mouth appropriately.

The problem I am encoutering is that the partilces tracks are not picked up. I have set it so 10,000 particles are to be sprayed on to the human head. Though when i run the simulation and go to the particle tracking results only 10% of the particles I input are being tracked. Of those tracked, the majority are also incomplete. Can anyone please help me?

Thankyou,

Mack
mack_johnson is offline   Reply With Quote

Old   March 15, 2013, 14:58
Default
  #2
Senior Member
 
A CFD free user's Avatar
 
A-A Azarafza
Join Date: Jan 2013
Posts: 226
Rep Power: 14
A CFD free user is on a distinguished road
Hi mack
The success in DPM model to track particles needs somehow trick. First you gotta receive a converged single phase solution which is either gas or liquid, then injecting your particles. I had your problem once, but I did it myself in my case. Stick in your mind that you need to adjust both time step and step size correctly to be able to track all particles. The first thing is that you need to increase the maximum number of steps. There's a rule of thumb, I recall that the multiplication of the numbers of cell in flow direction by step size should be equal to Max number of iteration. Hope it help
A CFD free user is offline   Reply With Quote

Old   April 27, 2013, 06:02
Default
  #3
Member
 
sajeesh
Join Date: Feb 2013
Posts: 52
Rep Power: 13
sajeesh is on a distinguished road
hello....
There's a rule of thumb, I recall that the multiplication of the numbers of cell in flow direction by step size should be equal to Max number of iteration.

i am not getting that.
How i get the number of cells in the flow direction.


two doubts also
what is DPM concentration


It is show that Residence time *mass flow rate of particle /cell volume

What is the meaning of residence time and cell volume...


How exactly i can select certain number of particle in the domain
sajeesh is offline   Reply With Quote

Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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 Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
how to determine the number of particles injected. welch FLUENT 2 January 18, 2024 05:08
UDF for deleting particles in DPM imanmirzaii Fluent UDF and Scheme Programming 12 November 25, 2020 20:27
trying to simulate two-phase jet flow with particles in surface injection ajkratos FLUENT 5 March 3, 2015 22:33
Straight through cyclone with particles rogerhoffmann CFX 1 May 21, 2012 19:42
particles model ati_ros61 FLOW-3D 3 December 6, 2009 17:03


All times are GMT -4. The time now is 16:16.