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

Injection of specific number of particles in DPM

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

Reply
 
LinkBack Thread Tools Display Modes
Old   October 20, 2006, 23:41
Default Injection of specific number of particles in DPM
  #1
DH
Guest
 
Posts: n/a
Hi, I am trying to inject specific number of particles on a wall boundary with 3-D DPM model. I am running Fluent in windowXP.

Could anyone tell me if I can use the DEFINE_DPM_INJECTION_INIT to specify

1. the number of particles

2. location of injection

3. particle size

I tried to follow the 4.6.5 Fluent UDF manual. But, it is not the the similar case with the model I want to make. I just want to inject solid particles on the wall surface & track them in 3-D airflow.

If you tell me any way to inject specific number of particles, it would be great?

If possible, could you send me simple code doing this?

Thank you ahead

DH
  Reply With Quote

Old   October 23, 2006, 12:09
Default Re: Injection of specific number of particles in D
  #2
Allan Walsh
Guest
 
Posts: n/a
Why are you using a UDF to do this? Why don't you just use the Set Injection menu? Or if your set-up is more complicated, make a file with particle data and read that in - according to the specifications given in the manual.
  Reply With Quote

Old   October 23, 2006, 15:17
Default Re: Injection of specific number of particles in D
  #3
DH
Guest
 
Posts: n/a
Thank you for the reply, Allan. You are right. I can use the group injection panel to inject specific number of particles.

But I would like to ask you how I can inject specific number of particles having different diameters. For example, if I want to inject 10 paricles of 1 micron and 5 particles of 10 micron in a specific location, how can I manage it?

Also, the manual was saying "looping over particle". Does that mean I first inject particles in the specific location then adjust parameters such as particle diameter or density by using UDF function? Sorry, I am a novice and confused.

Could you help with this? Thanks ahead

DH

  Reply With Quote

Old   October 27, 2006, 15:18
Default Re: Injection of specific number of particles in D
  #4
Allan Walsh
Guest
 
Posts: n/a
Make two injections - particles of 1 micron and particles of 10 microns. Why does the particle diameter change? If reacting, then you need to set up specific laws. In general, the UDF's are not for novices.
  Reply With Quote

Old   October 27, 2006, 15:48
Default Re: Injection of specific number of particles in D
  #5
DH
Guest
 
Posts: n/a
You mean I can make different two injections on the same location?
  Reply With Quote

Old   October 30, 2006, 09:35
Default Re: Injection of specific number of particles in D
  #6
Abigail
Guest
 
Posts: n/a
Yes you can, for each injection you specify the particle position, velocity, diameter, mass flow. If you wish to keep the position the same for several injections you can.

It is also possible to do a group injection and specify a range of diameters.

  Reply With Quote

Old   July 12, 2010, 13:55
Default how can I increase the number of injected particles?
  #7
Member
 
Shawn Fotovati
Join Date: Jul 2009
Location: Cincinnati, OH
Posts: 41
Rep Power: 9
sfotovati is on a distinguished road
Dear users,
I know that the maximum number of injected particles from any surface is equal to the total number of mesh points over that surface. is there any way that I can increase the injected particles number more than number of cells?
sfotovati is offline   Reply With Quote

Old   July 13, 2010, 02:49
Default
  #8
New Member
 
Rok Sibanc
Join Date: Sep 2009
Posts: 9
Rep Power: 8
snow is on a distinguished road
Why not use file injection?
snow is offline   Reply With Quote

Old   October 18, 2011, 12:58
Default Injection for a while but once from each point
  #9
New Member
 
Join Date: Feb 2011
Posts: 7
Rep Power: 7
Gold is on a distinguished road
i am doing some resuspension study, i am doing unsteady simulation and the effect of flow on resuspension, i use UDF for knowing whether the removal force of particles are enough for resuspension or not but the problen is injection takes place several times from one point but in reality the amount of particles in each cell are limited and once they resuspend it should not exist there?

do you please give me some idea about this situation?

thanks
Gold is offline   Reply With Quote

Old   October 18, 2011, 15:02
Default Re
  #10
Member
 
Domenico
Join Date: Sep 2011
Location: Atlanta
Posts: 39
Rep Power: 6
doronzo is on a distinguished road
Hello

One thing, I think, important to keep in mind in this discussion is that Lagrangian particles here are clusters of particles, and the total number of clusters calculated in a DPM solution is related to mesh and time step. The total mass injected in time (kg/s) is thus subdivided in a discrete number of clusters, and this number is the number of cells through which the injection occurs. If I want to inject for example 10 particles, probably I need a boundary that has 10 cells; in that case, the number of clusters corresponds to the actual number of particles I want to track. What do you think?

Regards
doronzo is offline   Reply With Quote

Old   October 20, 2011, 02:35
Default
  #11
Member
 
Join Date: Apr 2009
Location: Pune
Posts: 37
Rep Power: 9
Sushilkumar is on a distinguished road
You can use 'Random Walk Model' to increase the number of particles in multiple of the cells you have on a specified surface. e.g. for 10 cells you and define the number of tries in Random walk model as 5 and you will get 50 particles.
Sushilkumar is offline   Reply With Quote

Old   October 20, 2011, 07:50
Default
  #12
Member
 
Domenico
Join Date: Sep 2011
Location: Atlanta
Posts: 39
Rep Power: 6
doronzo is on a distinguished road
50 particles, or 50 clusters of particles?

In other words, given the total mass of solid to be injected, is that mass subdivided in 50 entities? (in a specific time)

Thanks
doronzo is offline   Reply With Quote

Old   March 16, 2016, 22:04
Default
  #13
New Member
 
Fangfang Sun
Join Date: Mar 2016
Posts: 3
Rep Power: 2
ffsun is on a distinguished road
Could you tell me how to write injection file ?

Actually i know the format of the file,but the question is: if i want to injection a large number of parcels,i will write and write so many lines,and i don't know the x y z position the parcels should be.

If i use surface file,it should be on core of every mesh,but how to get every core's coordinate?

and how to write this file using c language ?

ffsun is offline   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
DecomposePar unequal number of shared faces maka OpenFOAM Pre-Processing 6 August 12, 2010 09:01
Dense DPM Injection Help (basic sedimentation) sgelman FLUENT 0 July 21, 2010 14:19
air bubble is disappear increasing time using vof xujjun CFX 9 June 9, 2009 07:59
Two-Phase Buoyant Flow Issue Miguel Baritto CFX 4 August 31, 2006 12:02
DPM, UDF, Injection Type Zhang FLUENT 0 June 8, 2005 15:51


All times are GMT -4. The time now is 05:44.