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

question of DPM model

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   October 10, 2002, 17:19
Default question of DPM model
  #1
Cindy Jones
Guest
 
Posts: n/a
Hi, everyone I have two questions on the DPM model. 1. If my volume friction is larger than 10%, let say about 40%, can I still use DPM model to get rough results. If not, which kind of model I should use. ( I need to know the partical distribution)

2. How can I know the grid resolution is collect for the DPM model. I have a simple case, with different size of grids. One has 20,000 grids, for this case, I got 2500 particles. The other has 50,000 grids, I got more than 5000 particles.

Many thanks
  Reply With Quote

Old   October 10, 2002, 17:52
Default Re: question of DPM model
  #2
CFD Newbie
Guest
 
Posts: n/a
If your volume fraction is greater than 10% you must use the granular model as DPM won't account for particle-particle interactions that are important.

For the other question, the grid resolution is immaterial.

regards.

CFD Newbie
  Reply With Quote

Old   October 10, 2002, 18:30
Default Re: question of DPM model
  #3
Cindy Jones
Guest
 
Posts: n/a
Thanks for your reply.

Could you tell me that why the grid resolution is not important? how can I tell my result is correct if I got different results by using differnt number of grids? And why I got differnt particle number? Sorry for so many question.

Many Thanks

Cindy
  Reply With Quote

Old   October 10, 2002, 23:21
Default Re: question of DPM model
  #4
CFD Newbie
Guest
 
Posts: n/a
For the sake of the particles, resolution is not important but you must do the grid analysis until you obtain independence for the resolution of the flow equations.

Fluent releases a particle for every cell you have in the surface, so the more cells you have the more particles.

If you analyse impact of particles, look at the percentages instead of the absolute number.

The only way to know if your simulations are OK is by comparing them with quality experimental results.

Cheers

Newbie
  Reply With Quote

Old   October 11, 2002, 14:54
Default Re: question of DPM model
  #5
Cindy Jones
Guest
 
Posts: n/a
Thanks so much for your help.

Have a nice weekend

Cindy
  Reply With Quote

Old   October 17, 2002, 04:46
Default Re: question of DPM model
  #6
Laika
Guest
 
Posts: n/a
some comments:

--with volume fraction of 40 % you should indeed not use DPM. Granular can be an option, but maybe the particles are not granular. What kind of particles do you have, Cindy? Droplets, powder, ...?

--CFD Newbie tells Fluent releases one particle per cell. That's indeed the case with a surface-injection (and more correctly: it's one particle per face), but there are numerous other possibilities. You can also create an injection-file and release as much particles as you want.

--The grid resolution needed for good results have indeed nothing to do with the dpm-model. If you don't have experience with modelling for your application, you should test several grids and compare the results.

good luck,

Laika, still orbiting
  Reply With Quote

Old   October 25, 2002, 00:51
Default Re: question of DPM model
  #7
yawi
Guest
 
Posts: n/a
where is Granular model?
  Reply With Quote

Old   October 25, 2002, 04:51
Default Re: question of DPM model
  #8
Laika
Guest
 
Posts: n/a
it's one of the options for Eulerian multiphase simulation.

Laika, still orbiting
  Reply With Quote

Old   November 18, 2002, 22:58
Default Re: question of DPM model
  #9
revalin herdianto
Guest
 
Posts: n/a
Hi Newbie, you said that fluent releases particles at every cell? Does not fluent release particles on the surface that you define (for instance, inlet surface?)
  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
Question on introducing new terms into an existing model 351Cleveland OpenFOAM Programming & Development 0 January 26, 2011 07:48
C_UDMI Question in DPM Prashanth FLUENT 5 August 20, 2009 05:35
URGENT QUESTION ABOUT DPM EROSION!!!!!! alex FLUENT 2 October 28, 2005 07:33
DPM model in FLUENT Jürgen Schmidt FLUENT 0 October 27, 2005 15:39
DPM vs Species transport model osh FLUENT 0 August 19, 2005 23:15


All times are GMT -4. The time now is 04:12.