LIGGGHTS® - User Forum

HI,
Can anybody help me how to find total number of slip events in a time step in granular simulation.
I tried adding a counter in pair_gran_hooke and also a compute flag in compute/pair/gran/local. But it is not working. Can anyone help please.

saikat

Hi all,

I am doing my master thesis (simulation of roller compaction-pharmaceutical powder).

I have verry big problems with high number of particles (mean diameter is 120 µm).

For 1 g of powder I need 700 000 particles. That is a lot because for filling volume of roller compactor I need "rough estimation" 20 milion particles.

So for that many particles I don't have proper hardware.

In roller compactor I must meausre density in specific regions (picture "Density measure").

Hi All,

I have a physical system (fully loaded material bin with stones) which physically discharges the material contents in 95 seconds.

I have the same system in DEM (same physical dimensions for the geometry and particle sizes), with a time step of 1.0E-6 sec. The DEM system completely discharges in 20 seconds (20.0E6 time steps).

I mean to ask if there is a relationship between physical discharge time and simulation time. Is there anything wrong with this simulation? Does the DEM system really need to discharge in 95 seconds as in physical system?

Hi

May someone assist with how to upgrade liggghts to the current version. I am currently using version 3.4

Thank you

Hi

May someone help me with how to compute the total mass of multispheres in the computational domain please.

Thank you

Hi everyone,

I am running a simulation and observe a kinetic energy shift between runs

this is a part of the log file of my simulation. after the following run start, the kinetic energy shift up. what may be the reason? Between two runs, I only add dump command without changing any properties.

Hello everyone,

Do i need to import a CAD-File (such as .stl) in order to be able to create a moving wall or can i just define a moving domain/plane?

Thanks!

Hi everyone,

I just update liggghts into 3.7 from 3.6. I did a test with the same input file in both 3.6 and 3.7. however, the fix move/mesh gave me different result.

fix vibra all move/mesh mesh bottom viblin axis 0. 0. 1. order 1 amplitude 0.0025 phase 1.57 period 0.02

What is the motion produced by this command ?

According to the documentation, in 3.7, it seems this command has a different meaning. I can't remember the meaning in 3.6. In practice, 3.7 give the wiggle command to produce a sine motion of the mesh while 3.6 didn't (I think).

I can see from the new version of LIGGGHTS that dissipated energy can be tracked. Can anybody help me in how to dump the dissipated energy. Thanks in advance

computeDissipatedEnergy values = 'on' or 'off'
on = the normal model saves the dissipated energy for each contact for the
use in fix calculate/dissipated_energy

Hi

May someone assist on how to get the total mass of particles in the domain when using multispheres. i discovered that creating a group variable does not work with multispheres.

Regards