LIGGGHTS® - User Forum

Hello Friends, Greetings.

Lets say we have a cuboid container defined by 6 primitive planes oriented along X-Y-Z axes, filled with spherical particles to a certain height, gravity acting along Z. When this system is at rest,

1. How can we calculate net downward force acting on bottom wall (as a single value)? This must be equal to weight of all particles combined.
2. Is it possible to get force field on this bottom wall? This must be uniform, vectors pointing downwards (assuming flat or constant hFill) and sum of all field must be equal to weight of all particles.

hi i need to charge particles the set command charges atom or molecules i need granules charged to insert them in an electric field to change the particles directions if anyone could help me it would be great i could not find a solution i wanna perform the same thing as in the electrostatic example in the site https://www.cfdem.com/electrostatics thanks in advance hope someone helps me i am stuck for weeks on this thank you in advance

I'm trying to run a simulation like that in Podlozhnyuk et al. (2017) Fig. 7, where superquadric particles are piled up in a container. However, in a small test with 138 I find that the particles fall towards the bottom surface then start to 'dance around' and they never come to rest (see attached animation). I've tried altering the simulation parameters, including adding coefficient of rolling friction, but the problem still occurs. Could anyone suggest what might be incorrect or missing in the script (below).

Many thanks !

Liggghts version 3.8.0

Hi,all

I need to define two “pair_style” using “pair_style hybrid”,however,I faced an error.

ERROR:Incorrect args for pair coefficients

Here is the part of my input script.

pair_style hybrid gran model Hooke tangential history gran cohesion easy/capillary/viscous
pair_coeff * *

Thank you.

Hi,

i have the common task to track the mixing status in my apparatus. For this i need to find the number of particles Type 1 and Type 2 in specific regions. Lets say i want to have cylinders and count the number of particles in them every 10000th time step and print the result to a file, How can i do that? Is there a way to do that in the input file?

Thanks and kind regards

hello everyone hope ur all well i am stuck on a problm i am trying to make a script to push or attract particles using an electrostatic field but i have a problme the same error keeps popping and i could not resolve the problm i know it is not a big problm for some of you but it is for me and i would apreciate any tips on how to improuve my script to reach my goal it is far from finnished thank you all

ERROR: Numeric index is out of bounds (../force.cpp:786)

#falling particles in electric field

Hello Team,

Greetings. I hope, you are all doing good. I'm working on homogeneous simple shear simulation using the following two methods.

I'm trying to use rRESPA with a fix, however without the fix_modify respa options in lammps I'm unsure how to set the loop to apply fix forces at. Does anyone have any experience with this in LIGGGHTS? I see many fixes, such as fix_efield have rRESPA infrastructure in their code.

Thanks,
Thomas Leps

Hello everyone, I want to obtain a densest sample with equal sized spheres. I am using radius expansion method，and there is a factor named alpha target，referring to the packing density after expansion(I guess)，and I want to know the maximum value of this factor that can be used,thanks.
Best regards.
Zhao

hello everyone i hope ur all doing well i am a new ligggths user i need help i want to add an electrostatic field to attract granuls or push them if possible with positive and negative voltage to make a granular separation i am trying to modify the chute wear scrit by adding efield command but it's not working getting the following error thank you all

atom_style hybrid charge granular
atom_modify map array
boundary f f f
newton off

communicate single vel yes

units si