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Mohsin April 9, 2010 04:02

can anybody please tell me how to use "group" injection type in DPM model.

I have a circle having a diameter of 7.6 mm and all the particles will flow through it uniformly. Can anybody tell me how can I work on Group injections to make it flow throughh the circel unifomrly.


sydney_tekam April 12, 2010 05:43


Make a "surface injection" .
As a surface to release your particle from select your circle.

Mohsin April 12, 2010 10:00

Thank you

At last somebody replied here:) Actually I need to increase the number of particles

As u may know that for increasing number of particles there are 2 ways. First you can change the mesh size or u can use group injection. So i opt for group injection coz uincreasing number of mesh size is not a good way.


When i used "group" injections in DPM injection panel, The track summary gave me the message "104 particles not found in injection-0 ", My injection center point is (0,0,60) from center (0,0,0).

First point Last point
X position=-3.8 X position=3.8
Y position=-3.8 Y position=3.8
Z position=60 Z position=60

The upper inlet is 60 (positive z direction) from the center (0,0,0). The upper inlet circle's radius is 3.8 from where the coal will come. So from -3.8 to 3.8 in x and y directions the 104 particles would be injected (as the particle stream is 104).

Your suggestion may of help to me:)

sydney_tekam April 12, 2010 10:25

is it a 2D or 3D case?
I was under the impression that group injection is only to inject particle on a straight line pattern????!!!
so what do you expect with this type of injection (group onjection i mean)

Mohsin April 12, 2010 10:38

Yes it will inject particles through a line. for example

X position=-3.8 X position=3.8 with particle streams =3

then from -3.8 to 3.8 on the line 3 particles will be injected. first at -3.8 second at 0 and the third at 3.8. Thats what i know.

For my case I have a circle (3d case). I have to inject particles throughout the crcle for that reason what i can do is to divide the circle among several lines and create groups.

But its giving me error when i include z direction. I dont know what is the problem.

My querry has been discussed before as well. But actually i still dont understand what to do. They are talking about tolerance. I did what they said but still it didnt work. If u understand. It would be a great help for me:)

and here question number 1

alikami May 3, 2010 04:10

Do check units of mesh and injection are they same..

Marta December 13, 2010 11:18

Dear all, I am trying to set up a test case where i need to have the injection of particles from a surface.
I would like to use the dpm for this and to use one of the injectors model available.
Anyway, I am unable of setting the model correctly and i also have problems with the boundary conditions, since the dpm window says that it is not available and that it is impossible to specify any data/BC for particles.
Can you help me solving my problem?

Thanks a lot,


alikami December 13, 2010 11:45

your case ,,,2D axisymetric or 3D?

Marta December 13, 2010 11:56

Thanks for the quick reply, it is a 3D case.

alikami December 13, 2010 14:03

normally iits easy to define a surface injection just slectting the surface ( which may be inlet boundary or out let or somewhere in between flow)thats all...
you can give temperature , density , mass fraction and distribution ... not able to understand if you are mentioning the same or anything else?

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