LIGGGHTS® - User Forum

Plz see attached triaxial simulation

Problem : Particle are not compressing during the simulation.

Any COMMENT/help will be highly appreciated! Thanks

Hello,

I am trying to model a packed bed situation with a bottom wall of temperature 1000K and allow conduction through the bed. (This would involve inter-particle conduction as well).

I have been trying to add in a fix heat/gran/conduction value to allow for particle-wall conduction with no luck (no heat transfer happens at all). Can someone help me out? I am quite new to LIGGGHTS. I have attached my base code which has a heat source and sink which I do not want either - just conduction due to the heated wall.

Thanks

Hello everybody,

in LAMMPS documentation it is recommendet to use colloid and yukawa/colloid for DLVO potential.
I'm trying to use DLVO in LIGGGHTS (CFDEMcoupling) and now I stuck with the equations in colloid.
In LIGGGHTS only colloides are calculated, solvent is done by continuum. Does this mean the equations for colloid-solvent and solvent-solvent are not considered? Or is it computed with information transfered in the coupling?
Is there any hint, documentation or literature?

Thank you.

Henrik

Hi All,

I have a small question. Is the output results of LIGGGHTS simulation with same conditions differ? If say three or so same cases, same set-up, same conditions and same configuration are run, will there be any deviation?

Thank you.

I want to create cylinder(at coordinates 0, y,0) of radius 12.25 cm and o.74 cm height for region to insert particles. but its not creating at exact position.

Please help me. Code below

### Initialization

# Preliminaries
soft_particles yes
units cgs
atom_style sphere
boundary p p p
newton off
communicate single vel yes

# Domain
region reg block -1 1 -1 1 -1 1 units box
create_box 3 reg

### Setup

Hello everyone,

Right now I conducting a undrained triaxial test. The top and bottom walls are moving closer to compress the particles by "fix move/mesh" command and then the position of the side walls can be calculated. But I am confused on how to control the position of the side wall. I searched in the forum and found that in the old version of LIGGGHTS, the position of side walls can be controlled by "fix move/mesh/gran variable" command, but now this command doesn't exist anymore. Does anyone know how to control the side walls?

Thank you so much!

Dear LIGGGHTS users,
In LIGGGHTS for the integration of the velocity and the position we use a velocity Verlet scheme. This choice is motivated by the fact that we need to have a global conservation of the energy in our system. That’s why it is important to use a symplectic integration scheme.

Im getting these error. Please help me to solve this

Hello Friends

I am doing a small exercise to match the axial direction stress (sigma_zz) using the following two commands
(1) ave/time
(2) stress/atom

In order to calculate the axial stress from ave/time, perhaps I need to divide the z-direction force with piston area.
And from stress/atom command, I guess, will get directly the axial stress (sigma_zz) by using the following snippet

I'm setup a simulation where I'm pouring particles into a geometry to form a stack of particles. The particles are the agglomerating together with a cohesion model and I notice that the computational resources is increasing with increased number of particles (as one would expect).

For many of these particles they will not move anymore since they are just agglomerated together and have many contacts so I would like to skip the calculation on these particles and just freeze them instead such that Liggghts does not calculate the contact forces and they will then just act as a wall.