LIGGGHTS® - User Forum

Hi, I have a question about the value of the force and how it come from.

I did the simulation and dumped the file for contact and atom.

I get the atom data using 'dump aa all custom time id type x y z vx vy vz fx fy fz ...'

And the contact data using 'compute bb all pair/gran/local id pos force_normal' and dump it.

Hello Everybody,

I am absolutely new to LIGGGHTS. I tried to run template script on cluster. When I run from cmd it works, but when I try to integrate it with slurm, I get this error:

ERROR: Invalid command-line argument (../lammps.cpp:271)
Can anyone help me to solve this problem?

Thanks in advance,
Omid.

Hello LIGGGHTS forum.

Really thank you for your help. You guys have been amazing in my research journey.

I have one more question regarding cohesion.

I am trying to add cohesion model in my simulation. Right now I am using following model as mentioned below:

pair_style gran model hertz tangential history #Hertzian without cohesion

Right now I am using inclined surface with atom style granular.
I went through liggghts tutorial regarding `gran cohesion sjkr model`. But couldn't find the exact way to apply cohesion with value.

Hello LIGGGHTS forum,

I am confused regarding region bc coordintes.

Could you please explain me about the coordinates which are used as 0.0, 0.0. 0.15, 0.05, 0.12 ?

In this command :

region bc1 cylinder z 0.0 0.0 0.012 0.01 0.05 units box

I know this is a silly question. I went through the LIGGGHTS tutorial but still couldn't make my self clear?.

Thank you

Hello,

Hello everyone,
This post is to follow up with a problem of "isolated particles" (particles having no contacts with other particles) having such a high and unreasonable omega, especially around the base of the pile. This problem was mentioned a few years ago in this thread: https://www.cfdem.com/forums/constant-high-omega-few-particles-close-bas....
I just wonder:
1) Does anyone know how to fix or work around this problem? Any ideas are highly appreciated.

I am currently doing my research on metal 3-d printing and I was hoping if anyone can help me set up a powder bed using liggghts.
Thanks in advance.

I am currently doing my research on metal 3-d printing and I was hoping if anyone can help me set up a powder bed using liggghts.
Thanks in advance.

I'm trying to simulate particles with radius 0.0002m (200 micrometers). If I used "SI" units the required dt is about 1e-6 second.

Does using "micro" units in liggghts instead of "SI" units accelerate the run time since the time unit in "micro" unit system is microseconds not second, so dt will be equal to 1 microsecond?

Is there any differences in the output results if simulating the same problem with different unit system?

I'm generating particles in script (1) then save a restart file. Then apply some forces on the particles in script (2) after reading the restart file.

My question is can I define different inter-particle interactions in script (2) without changing it in (1) or they must be the same since script (2) reads the restart file of (1).

I want to do that to avoid running script (1) each time I need to change these parameters to save time.