LIGGGHTS® - User Forum

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

Hi

I am using multispheres in my simulation. I have created variables because i would want certain quantities to be printed to screen as the simulation proceeds however i am getting an error "Variable command group may not be used together with fix multisphere". May someone assist on how i should use variables in a multisphere simulation

Thank you

I need to insert spherical particles of size varying from 0.0001m to 0.00001m (diameter) into a container until the container fills completely. Without feeding no of particles as input data how can i formulate the syntax for this condition.