Something about raindrops simulation by DPM

Byron · July 25, 2009, 05:23

hi ,everybody.
I meet some troubles about raindrops simulation by DPM.
I want to simulate full-scale raindrops by DPM.I use the surface injection.

the computional domain is 3D and is very large,900*900*3000(height).
So, the number of raidrops in domain is very very large with exceeding 1E+12.

The bounded face was adopted as surface injection.

Now, if I want to simulate this project, the grid faces in bounded face (surface injection) were very very large numbers .And , it must exceeds the capitcy of the Computer .

Is any other way which I can choose to avaoid this problem?
please.

Geisel · July 25, 2009, 09:19

As I suppose, you want to decrease the number of raindrops tracked by DPM analyse.

The number of tracked particles in surface injections depend of the number of cells used to create this surface... something like that

And there is no option to change the numbers.

There are two options...

You can use UDF (I have readen somewhere here about it, but never used it)

or you can use injections from file...
just create a file in notepad. Rename it to blabla.inj
And inside write some lines (you can use Excell to compute this) like:

Code:

(( x y z u v w diameter temperature mass-flow) name )
x,y,z - location
u,v,w - velocities
each in SI units

eg:
((0.01 0.03 -2.1 0 0 -4.5 0.00004 123 0.001) 1)
((0.02 0.05 -1.9 0 0 -4.5 0.00004 123 0.001) 2)
...
...
((0.121 0.123 -67.1 0 0 -4.5 0.00004 123 0.001) 1131)

Check User Guide for more information.

Hope it will be works.
Regards

Byron · July 25, 2009, 21:01

Thanks for Geisel

your reply give me a lightpoint,especially the second option would fit my problem well.I will try it immediately.

Lastnight,I also thought another way that I will divide the full-scale computational domain into 12 parts by 30 degrees each part ,because the domain is axial symmetrical. I will carry out calculation only on one part.
Then ,the domain is redued and the total drops is also reduced spontaneously.

July 25, 2009, 05:23	Something about raindrops simulation by DPM	#1
Byron New Member Join Date: May 2009 Posts: 8 Rep Power: 17	hi ,everybody. I meet some troubles about raindrops simulation by DPM. I want to simulate full-scale raindrops by DPM.I use the surface injection. the computional domain is 3D and is very large,9009003000(height). So, the number of raidrops in domain is very very large with exceeding 1E+12. The bounded face was adopted as surface injection. Now, if I want to simulate this project, the grid faces in bounded face (surface injection) were very very large numbers .And , it must exceeds the capitcy of the Computer . Is any other way which I can choose to avaoid this problem? please.

July 25, 2009, 09:19		#2
Geisel New Member Luk Join Date: Jun 2009 Posts: 24 Rep Power: 17	As I suppose, you want to decrease the number of raindrops tracked by DPM analyse. The number of tracked particles in surface injections depend of the number of cells used to create this surface... something like that And there is no option to change the numbers. There are two options... You can use UDF (I have readen somewhere here about it, but never used it) or you can use injections from file... just create a file in notepad. Rename it to blabla.inj And inside write some lines (you can use Excell to compute this) like: Code: (( x y z u v w diameter temperature mass-flow) name ) x,y,z - location u,v,w - velocities each in SI units eg: ((0.01 0.03 -2.1 0 0 -4.5 0.00004 123 0.001) 1) ((0.02 0.05 -1.9 0 0 -4.5 0.00004 123 0.001) 2) ... ... ((0.121 0.123 -67.1 0 0 -4.5 0.00004 123 0.001) 1131) Check User Guide for more information. Hope it will be works. Regards __________________ *******************************

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July 25, 2009, 21:01		#3
Byron New Member Join Date: May 2009 Posts: 8 Rep Power: 17	Thanks for Geisel your reply give me a lightpoint,especially the second option would fit my problem well.I will try it immediately. Lastnight,I also thought another way that I will divide the full-scale computational domain into 12 parts by 30 degrees each part ,because the domain is axial symmetrical. I will carry out calculation only on one part. Then ,the domain is redued and the total drops is also reduced spontaneously.