LIGGGHTS® - User Forum

Hi

I would like to impress a force on each atom depending on his mass, velocity an position. While searching through the manual i have found the fix command addforce. I have read "the vector is the total force on the group of atoms". So thats not what I need. But I couldn't find any other fix command that would enable my additional force. In the forum I've read that in a coming version of liggghts variables could be used in fix addforce. Is this in the newest version 1.5 possible? Would that help?
How would you impress an additional force to each atom?

I am trying to simulate mixing of granular particles in a rotary drum mixer. How can give different values to young modulus, coef of restitution, etc for particle particle interaction and particle vessel interaction cause.

Hello everyone!

I am new to this site and forum.
Therefore I want shortly introduce myself:

I am a student from Düsseldorf, Germany
working on my master thesis now.

My job is to simulate a ball mill for grinding processes.
It is similar to the one you have on this site.
A rotating cylinder with steel balls in it should be simulated.

I am new to LAMMPS and LIGGGHTS.
Moreover, I never used Linux, nor have I used or programmed in C++.

What is a best/efficient way to start?

Should I at first get familiar with LAMMPS/LAMMPS manual
or something else?

Hey all, I just wanted to share this. I'm working on a tool-soil interaction problem in which both the displacement of the soil and the deformation of the tool is important. I will be coupling LIGGGHTS and Code Aster to perform the simulation. I have started a blog to document my progress (and to keep me motivated!!!)

It can be found at http://coolsimulations.wordpress.com

Hello all, hi Moritz!

Because of the forum threat SPH and walls you find attached my input script.

@Moritz: Two mistakes were in your input script:

• Regions may not overlap in areas, which should be treated as walls.
• In your case the union-command creates additional convex corners, which are not calculated accurately.

I inserted also comments to my modifications.

I modified your script only for bug fixing. I did not check any physical properties (viscosity,...), time step, ...

Hello! Does anyone have any good ideas if I'm trying to create a follower force. In other words, I want a force that changes direction as a particle rotates. I cannot find any commands to create mobile coordinate systems on particles, is there another way?

Thanks,
Zamir

Hello dear liggghts community members !

I'm interested to simulate using the SPH pairstyle cooling and subsequent solidification of a mixture of 2 liquid phases.
I know there's a heat conduction fix in liggghts , but i'm not sure if the sph particle parameters actually depend on temperature\pressure so the material properties could change appropriately to liquid->solid phase transition.

Is liggghts capabale of simulating solidification ? What would be a good start towards this direction ?

Hi Christoph,

I was wondering, how do you generate non-spherical particles in LIGGGHTS according to the mesh scanned from Laser Scanner?

1) Simply fill in single particle inside the mesh manually with minimum number of particles?

2) or fill in automatically by means of certain algorithm according to the points or surfaces?

Hi Friends:

I don't know why I can not completely fill the container. Here is the snip of my code.

boundary p p f
region reg cylinder z 0.0 0.0 10 0.00 50 units box
create_box 1 reg
fix m1 all property/global youngsModulus peratomtype 5.e9
fix m2 all property/global poissonsRatio peratomtype 0.45
fix m3 all property/global coefficientRestitution peratomtypepair 1 .3
fix m4 all property/global coefficientFriction peratomtypepair 1 .5

pair_style gran/hertz/history 1 0 #Hertzian without cohesion
timestep 0.00001

fix gravi all gravity 9.81 vector 0.0 0.0 -1.0

Hi all,

I'm trying to write the total torque to an output file. For doing this I've read:
(1) Torque on axle exerted by particles (Forum-Post at 27.07.2011)
(2) Compute pair/gran/local (Forum-Post at 16.12.2010)
(3) fix print command (in the LIGGGHTS-doc)
(4) fix mesh/gran/stressanalysis command (in the LIGGGHTS-doc)
(5) fix_mesh_gran_stressanalysis.cpp (sourcecode)

But I do still not know how to write the total torque out. The question in (1) describes exactly what I will do.