Particle tracking inside LIGGGHTS

Submitted by e.derakhshani on Tue, 10/08/2013 - 17:06

Dear all,

I am going to track particles in my fluidised bed simulation. For instance , 1000 particles are inserted into the domain and I am going to track particles with the ID between 200 to 500.

Does anyone have an idea about how I can track particles based on their ID in LIGGHTS.

Best regards,
Ebrahim

Forums:

cstoltz | Wed, 10/09/2013 - 03:58

What do you mean by tracking them? Are you interested in just dumping out information related to those particles, or visualizing just that set, or what?

Regards,
Chris

e.derakhshani | Wed, 10/09/2013 - 11:28

first: I would like to tag some particles inside the fluidized bed and then I will check by running simulation how they are move between the other particles. Now I do not know how to tag particles.

Second: I need to measure void fraction in the specific height of fluidized bed. for this idea I should average void fraction every 10 ms of DEM simulation for 25 seconds. Do you have any idea about measuring void fraction in the DEM ?

P.S. All particles have the same properties.

cstoltz | Wed, 10/09/2013 - 12:37

You can dump information on specific sets of particles by creating groups and then only dumping the attributes of the particles in that group. Sounds like this will accomplish what you're describing trying to do.

For void fraction, I have always just dumped particle positions and then calculate offline using a post-processing script.

Regards,
Chris

e.derakhshani | Wed, 10/09/2013 - 17:08

Dear Chris,

Thanks for your help.

Best regards,
Ebrahim

e.derakhshani | Thu, 10/10/2013 - 15:52

Dear All,
I have currently changed pair_style from gran/hertz/history to gran/hertz/history/stiffness .
And then I had to change wall/gran/hertz/history to wall/gran/hertz/history/stiffness.

But after inserting particles into the domain, particles can not recognize the walls and move through the walls.
Also I have tested two types of wall: primitive and mesh and the result was same.

I have copy/paste some part of my code in the below.

I do appreciate to help me.

Best regards,
Ebrahim

atom_style granular
atom_modify map array
communicate single vel yes
processors 4 1 1
boundary f f p
newton off
units si

region reg block 0.0 0.044 0.0 0.120 0.0 0.01 units box
create_box 2 reg

neighbor 0.005 bin
neigh_modify delay 0

#Material properties required for new pair styles
#==========================================================
fix m1 all property/global gamman peratomtypepair 1 0.005
fix m2 all property/global gammat peratomtypepair 1 0.98
fix m3 all property/global kn peratomtypepair 1 1556
fix m4 all property/global kt peratomtypepair 1 888
fix m5 all property/global coefficientFriction peratomtypepair 1 0.1

#New pair style=================================================================
pair_style gran/hertz/history/stiffness
pair_coeff * *

# timestep, gravity
#==========================================================
timestep 0.000005
fix gravi all gravity 9.81 vector 0.0 -1.0 0.0

#granular walls
#==========================================================
fix inface all mesh/surface file ../DEM/geometery/insert.stl type 1 surface_vel 0. 0. 0.

fix bx all mesh/surface file ../DEM/geometery/box.stl type 1 surface_vel 0. 0. 0.
fix wall all wall/gran/hertz/history/stiffness mesh n_meshes 1 meshes bx

#fix x1walls all wall/gran/hertz/history/stiffness primitive type 1 xplane 0.0
#fix x2walls all wall/gran/hertz/history/stiffness primitive type 1 xplane 0.044
#fix ywalls all wall/gran/hertz/history/stiffness primitive type 1 yplane 0.0