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

DPM model problem

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   April 21, 2010, 06:07
Default DPM model problem
  #1
wwa
New Member
 
wwa's Avatar
 
Join Date: May 2009
Location: France
Posts: 14
Rep Power: 17
wwa is on a distinguished road
Hello all,

i have a problem with increasing number of particles tracked after each DPM iteration. Normally the number of particles is around 100000, but later it goes up to several millions and takes more time to calculate. i don't know why this happens . anybody has experienced similar problem?

i run steady simulation of combustion in 3D, standard k-epsilon, species transport model - EDC concept (with mechanism of 22 species and 49 reactions)

As for DPM, in total there are 36 injections of combusting particles, released from 2 symmetrical surfaces, with rosin-rammler diameter distribution. Each injection has different particle size range and devolatilizing species.

i also use udf for species source terms in one part of the volume, which is porous.

thanks in advance for any comments.

Peter
wwa is offline   Reply With Quote

Old   May 3, 2010, 05:00
Default Particle tracks
  #2
Member
 
ali
Join Date: May 2009
Posts: 58
Rep Power: 17
alikami is on a distinguished road
I think for staedy state , when you check particle tracks, It gives history of all particles tracked ...
meaning evry DPM iteration , it tracks particles from defined injection .
At end it gives results of all. so that if your dpm runs n times you have
n*100000 tracks , I hope i am correct.
Regards ali
alikami is offline   Reply With Quote

Old   May 3, 2010, 09:13
Default
  #3
New Member
 
Sydney Miles TEKAM
Join Date: Apr 2010
Posts: 7
Rep Power: 16
sydney_tekam is on a distinguished road
HI

Do you run couple or segregated solutions?
Are you simulations steady or unsteady for dpm?
sydney_tekam is offline   Reply With Quote

Old   May 3, 2010, 09:50
Default
  #4
wwa
New Member
 
wwa's Avatar
 
Join Date: May 2009
Location: France
Posts: 14
Rep Power: 17
wwa is on a distinguished road
thanks for replies.
dpm is also steady, and the solver is pressure-based so i guess it's segregated (i use Fluent 6.3).
also, i have to mention that it does happen only in one specific case. there is no problem in other cases with slightly modified mesh and very similar boundary conditions. total number of particles tracked there is always the same.

peter
wwa is offline   Reply With Quote

Old   May 3, 2010, 11:16
Default
  #5
New Member
 
Sydney Miles TEKAM
Join Date: Apr 2010
Posts: 7
Rep Power: 16
sydney_tekam is on a distinguished road
ok
is the option unsteady tracking activated?
sydney_tekam is offline   Reply With Quote

Old   May 3, 2010, 11:18
Default
  #6
wwa
New Member
 
wwa's Avatar
 
Join Date: May 2009
Location: France
Posts: 14
Rep Power: 17
wwa is on a distinguished road
no, unsteady tracking is disabled. i have never used it.
wwa is offline   Reply With Quote

Old   May 3, 2010, 16:26
Default
  #7
New Member
 
Sydney Miles TEKAM
Join Date: Apr 2010
Posts: 7
Rep Power: 16
sydney_tekam is on a distinguished road
You said that you were modeling combustion .
Have you activated droplet break up or coalescense?
Can you post a sample of your TUI report please?

Regards,
sydney_tekam is offline   Reply With Quote

Old   May 4, 2010, 10:26
Default
  #8
wwa
New Member
 
wwa's Avatar
 
Join Date: May 2009
Location: France
Posts: 14
Rep Power: 17
wwa is on a distinguished road
no, i didn't use droplet break-up as it is related to unsteady tracking.

to be more precise, i'm modelling wood particles combustion.
in total there are 36 injections released from 2 surfaces (18 per each).

or to break it down further there are 3 sets of injections by size (small, normal and large) per 6 devolatilizing species (co, co2, h2, ch4, c2h4 and c2h6). all injections have rosin rammler diameter distribution.

i'm not sure which part of the tui report are you interested exactly.
here is the sample of DPM iteration:

DPM Iteration ....
number tracked = 158040, escaped = 104527, aborted = 0, trapped = 0, evaporated = 0, incomplete = 53513, incomplete_parallel = 0
Parallel particle tracking concurrency: 38%


regards,
peter
wwa is offline   Reply With Quote

Reply

Tags
combustion, dpm, particles


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
DPM mass problem Henrik Ström FLUENT 9 May 20, 2016 12:00
Problem on EDC model for coal combustion lei FLUENT 4 September 3, 2015 10:39
lenght and number of nodes for an orifice meter flow problem - k-eps model fofo FLUENT 0 November 15, 2009 04:49
problem about DPM of cyclone separator simulation jason FLUENT 4 November 12, 2007 04:15
how to do with the DPM problem? x.p.lee FLUENT 1 June 26, 2003 14:07


All times are GMT -4. The time now is 18:37.