Dividing Domain into number of sections?

Submitted by kashif saeed on Mon, 08/28/2017 - 20:04

Hi everyone,

Can I divide my simulation domain into the number of section or parts in the paraview to find the number of particles in each sub section of the domain to find mixing index.

I have also attached the image of my simulation. I want to divide this into the number of subdomains to find the subdomain based mixing index.
Please help me
thanks

AttachmentSize
Image icon after_mixing.jpg107.53 KB

Forums:

kashif saeed | Tue, 09/05/2017 - 06:04

Thanks Omid dorostkar,
Can you let me know how can i creat these geometrical sections in liggghts.
You said that after making sections put it as a group, Did you mean making a whole one group?
Actually my problem is that i required subdomains/sections in which i want to find total number of particles in each section and also the type of particles separately.
Example
If in 1 section
Total particles 100
Type1 30
Type2 45
Type3 25

Can you help me. Thanks

ishaandesai | Thu, 09/07/2017 - 08:51

Hi Kashif,

You can define an atom style variable with the geometric limits of your sub-domain in x y z direction and then using this variable, you can group those particular particles under one group name.
Here is a small example of how you can go about this:

variable sub1 atom "z >= 0.13"
group subdomain1 variable surf1

This will pick all particles satisfying the geometric condition and put them in that particular group. Later you can try to output that group of particles in a dump file and then work your way to counting them as per your requirement.

kashif saeed | Fri, 09/08/2017 - 09:26

Hi ishaandesai,
I couldn't understand how to create subdomains. Now i am trying to explain my problem again.

I am using open source software LIGGGHTS, which uses DEM (discrete element method), My simulation contains a cylinder and 4 bladed impeller which rotates inside the cylinder. I have inserted 3 types of particles in the cylinder and rotate the impeller which causes mixing of particles that process is done using LIGGGHTS software.

Now for post processing, i am using ParaView. In Paraview, I can see the particles mixed each other. but I want to find out the mixing status for that purpose I want to use Subdomain based mixing index (SMI).

For SMI calculation, it requires dividing the domain into subdomains like 3D mesh and to find the total number of particles and number of particles of each type in each cell of mesh/subdomain.

Please let me know how can I create these subdomains in ParaView?
Or these sub domains be created in LIGGGHTS input script if it should be created in input file then let me know how can I create this in the input file.
For example
100 sub sections of portion of the domain in which particles exisits as shown in the uploaded figure.
And want to find total number and each type of particles in each sub section separately.
thanks

ishaandesai | Tue, 09/12/2017 - 06:34

Hi Kashif,
Do you need these sub domains to be in odd shapes ? Or are they just rectangular boxes / planar divisions of 3D space ?

I do not know how to define such sub-domains in LIGGGHTS and may be direct implementation will not be possible. But I have had the need to do such calculations for particulate systems and you can explore many commands given in LIGGGHTS to reach the result you need.
For example:
Once you have given 3 types to your particles, you can distribute them in groups according to their co-ordinate positions by the way I have suggested earlier. These coordinate restrictions will indirectly signify your sub-domains. When you have grouped the particles according to their positions, you can use a dump command to take the output in a vtu / vtk file for each timestep. Then you can open these files in ParaView and see the number of particles of each type in each sub-domain, as one group will now signify one sub-domain.

Cutting domains in ParaView might be possible, but I do not have any direct information on it.

Regards