LIGGGHTS® - User Forum

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?

Hello,

My final year part time master thesis is based on the shrinkage problem during the HIP (Hot Isostatic Pressing) process, which is based on my actual working experiences using the HIP process for an offshore oil and gas project.

Consequently I have a constructed the same dimensional cylinder (large volume cylinder) in autoCad Inventor replicating the same overall dimensions as previously used for this project. My thesis aim is to determine the various packing density values in the cylinder when raw particles are poured into the cylinder.

Hi Everyone,

For my simulations I'm slowly growing the simulation domain using a change_box command with scaling in the z direction.

The docs tell me that "the mapping of processors to the simulation box is not changed from its initial 3d configuration".

Does this mean that the processors on the z boundaries of the domain get the extra simulation domain? If so, is there a clever way to perform a "fools" load balancing step?

Thanks in advance,

Victor