LIGGGHTS® - User Forum

Im trying to insert particle into a cylindrical container and apply axial load on it over the top plate. But it is showing error
ERROR: Fix wall/gran (id geometry): More than one wall of type 'mesh' is not supported (/build/buildd/liggghts-3.0.3+repack/src/fix_wall_gran.cpp:505)

# Shear Cell example
### Initialization
# Preliminaries
units si
atom_style sphere
boundary f f f
newton off
communicate single vel yes
#processors 2 2 2

Dear community,

I am trying to understand the formula in the description of the gran Hertz model. Here is the question, do the Sn and St parameters have any physical meaning? Or they are just introduced for the sake of simplicity of the formula? And the second question: is it right that the gamma depends on the 1/4 power of the overlap?

Any reference for the formula origin are welcome? because the references in the manual do not contain it.

Thank you,
Oksana

Dear All

I have problem when I insert particles.
When I insert particle in cylindrical vessel, the particles stand like a pile.
How I can insert particles which the surface of particles will be flat.

I use below command to insert particles:
fix ins all insert/pack seed 1001 distributiontemplate pdd1 insert_every once overlapcheck yes particles_in_region 15000 region insert_reg

Best Regards
Esmaeil

I need to simulate a loose packing of polypropylene particles.
What are the physical parameters I have to change and where can I found the right values for them?

Hello,

I have set up a 24-processors simulation that simulates slurry flow in an open-ended pipe. The slurry flows in from one end and flows out through the other end of the pipe. Fixed DEM boundary is used. Particles are counted and deleted using fix massflow/mesh with delete_atoms function. My simulation works fine for dilute slurry with large particles. But it almost always crashes when I use small particles and a concentrated slurry. (The total number of particles is on the order of millions.)

Dears,
I'm simulating a vibrating box with particles inside (see box.png) that it moves in the y-axis.
In my simulation particles explodes at certain instant time (see exp.gif). I saw some forum topics about this, but it isn't help me.

I try changing some parameters and when I change Young's modulus(from 23 MPa to 5 MPa) it isn't exploit.
I attach input script and geometries.

How i can solve this without change the Young's modulus?

Best regards,

I am attempting to make LIGGGHTS with openmpi and I am getting the following error near the end:

atom.o: In function `LAMMPS_NS::Atom::new_avec(char const*, char*, int&)":
atom.cpp: (.text+0x12a8): undefined reference to `LAMMPS_NS::AtomVecTri::AtomVecTri(LAMMPS_NS::LAMMPS*)'
atom.cpp: (.text+0x13b7): undefined reference to `LAMMPS_NS::AtomVecTri::AtomVecTri(LAMMPS_NS::LAMMPS*)'
colect2: error ld returned 1 exit status

Could someone provide some guidance on how to resolve this issue? What step/steps am I missing?

Thank you!

Hi all

I'm a new user of LIGGGHTS 2.2. I'm trying to build a simulation to calculate slury flow with large particles.
Unfortunately I have one problem. I need to change the drag force on the particle with the velocity. (Ex. drag = 0.0 when v = 0.0, drag = 1.0 when v > 0.0 ) So I try to use the if-statement in the script but I can not access to the velocity information of the particle in the if statement. I don' why. Maybe I guess if-statement part is no good.

Please give me advise and helpful information !

# Slary Flow in Inclined Pipe

Hi everyone,
I am using sjkr and sjkr2 cohesion model in my simulation, but I cannot find any reference about these two models. Could anyone provide me some information about how those models are derived from the JKR model ?

Best,
xpqiu

Hi everyone, I have a question.
The command compute contact/atom define a computation that calculates the number of contacts for each atom in a group.

The contact number is defined for finite-size spherical particles as the number of neighbor atoms which overlap the central particle, meaning that their distance of separation is less than or equal to the sum of the radii of the two particles.

For spherical particles, all with the same diameter, the maximum contact number should be 6, but I've got also 7,8 or 9 contacts. Is it possible?