LIGGGHTS® - User Forum

Hi,

If possible can anyone provide the reference of hertz time provided in the LIGGGHTS manual?

dt_h = 2.87*(m_eff^2/(r_eff*Y_eff^2*v_max))^0.2.

Thank you.

Hello everyone! i tryed to use this command (you could see it below) to initiate simulation with parallel computing
The manual says that i should use this command
mpirun -np 8 liggghts -in in.script
i used for the chute_wear example
mpirun -np 8 liggghts -in in.chute_wear

But is doesn't work properly, i mean, it uses only one processor and the log says:
1 by 1 by 1 MPI processor grid
Loop time of 115.306 on 1 procs for 99999 steps with 834 atoms

Hi,

I'm looking for an open source / free DEM software for simulating the packaging process of a packed bed reactor. I need to calculate the voidage fraction of the resulting packed bed.

The bed consists of spherical and cylindrical particles of different sizes. I could not find this information in the documentation so I'm going to ask here: Is liggghts capable of running a simulation similar to this video: https://www.youtube.com/watch?v=C3uTXLfkY-Q

Hello Liggghts Team,

i am currently writing my thesis about analyzing the homogeneity of Packings created with LIGGGHTS and need to know which particle placement algorithm is implemented in the program.
It seems to be a Random Sequential Addition algorithm, but i don't know how it works exactly/if it uses any special implementations of RSA.
I tried studying the Sourcecode, but it's much to complex for someone with my limited programming experience :-).

Hello guys,

I want to loop every particle at the end of every time-step,then do some calculations about the arrays, reserve the values and return the values. So if I want to achieve this, what should I do?

Best regards,

LEO

Hi,

While setting up a case for a CFDEM simulation, we encountered a problem with the perceived packing density.

We first inserted the particles mid-air and let them settle. The bed height after settling was much higher than in reality, which is why we tried a higher gravity as well as shrinking the particles and cycling between growing and relaxing, to no avail.

Has anyone had a similar issue before? We would appreciate any response.

Hello guys,

I want to use DLVO forces in my simulation model. Therefore I need to use the pair_style colloid and yukawa, I guess.
I have read the manual of LAMMPS (http://lammps.sandia.gov/doc/Section_packages.html), but I still don't know, how to install the package colloid.

Hi,

I have a question to the combination of Hertz contact model and rolling model. Consider a particle with high overlap rotating in elastic region -> that results in a stiffer k_n and k_t -> results in a stiffer k_r in rolling behaviour. Now the overlap is reduced and the particles roll back -> kn kt is lower, also kr is lower -> results in a larger back rotation because of the lower k_r now. Attached is a sketch of this rolling case. So do I have to use hook if I want to use the epsd rolling model?

kind regards
Joshua

I'm trying to run a compilation using a hybrid granular molecular atom_style, but when i run LIGGGHTS, this error appears:

ERROR: Invalid atom_style command (../atom_vec.cpp:72)

I'm trying to solve this problem but even reading the documentation, i cannot find a solution.

PD: I'm using the 3.2.0 LIGGGHTS version

Cheers, Nicolás

Is there a way to simulate multispheres in LIGGGHTS without the particletemplate/multisphere command?. I'm currently working in a SAG mill simulation with a partner, and our boss ask to do the same simulation with multispheres... please, a hint would be more than useful.