LIGGGHTS® - User Forum

Hi,

When I want to create a particle at a desired location, an error is encountered.

create_atoms 1 single ${x1} ${y1} ${z1} units box, where x1, y1 and z1 are variables.
ERROR: Variable for set command is invalid style

create_atoms 1 single v_x1 v_y1 v_z1 units box
ERROR: Expected floating point parameter in input script or data file.

I also check the value of the variables by print.

print "The x1 is ${x1}"
The x1 is -0.0035

print "The y1 is ${y1}"
The y1 is 0

I am trying to simulate a deformable particle and I was wondering what you have experienced as a good atom_style to use.

Because I thought that the atom_style bond or body (from Lammps) would suffice, but both appear to be non-existent in the Public version of Liggghts. At least, I thought that atom_style bond would, but when using I obtain the error message "ERROR: Invalid atom style (../atom.cpp:432)".

Hence, what would you think is a good atom_style to use for a deformable (donut like shaped) particle?

Hello,

I'm developing a transfer chute simulation wich has more than a million particles in the scenery, and is taken a lot of time for running.

It's a symmetric problem, so I would like to know if LIGGGHTS has a function like symmetry plane, or something like that.

Best regards!

I would like some help on how to visualize your mesh in paraview and how to manage the output file concerning the mesh from LIGGGHTS.

For my output files I always use the following type of commands:

# Concerning a Continuous Blending Machine (CBM)
dump dmp all custom 1000 post/dump*.CBM id type type x y z ix iy iz vx vy vz fx fy fz omegax omegay omegaz radius

1. Whenever am I trying to run simulation using the hooke/stiffness model with the code give below the particles are passing through the zwall which they shouldn't. Can anyone please clarify that what is wrong with this code?

2. Can I define new model instead of using the predefined model for granular contact ?

3. While using the absolute_damping off in hooke/stiffness model, Is it possible to change the given formula for gamma_n i.e. from given formula (gamma_n-specified)*(m_effective) to (gamma_n_specified)* (m_effective)^(0.5).

There are predefined granular models provided in the LIGGGHTS Docs. Can I define the new model to use instead of using given models.
I want to use hooke/stiffness model but with a little modification. Can I do that ?

on doc page for gran model hooke/stiffness given description is

{
gran model hooke/stiffness

Syntax:

model hooke/stiffness [other model_type/model_name pairs as described here ] keyword values

zero or more keyword/value pairs may be appended to the end (after all models are specified)

Hi

I am new to LIGGGHTS and would like to ask the possibility of using this tool for DEM analysis of fibre reinforced clay soils where we need to define physico-chemical interactions between two clay particles (i.e., Van der waals and double layer forces) . Is this package suitable for this purpose?

I will be really pleased if experts can give me an idea.

Kind Regards
Mehdi

I just started out with LIGGGHTS and after running some of the standard tutorials, I found this Bin Flow turorial, which should work but is not working for me at the moment

Included is my case folder and when running this I get the following error:

Hello, (warning: new to liggghts.....)
I would like to add bonds to the particles from the hopper drain example.
Specifically I would like to bond multiple atoms together to create a ridged
group with the ability to break if a certain force is exerted on the bond.

I have attached a txt file that contains the tutorial script with added changes and both the input file
and script for the attempt at using atom style hybrid bond granular

Any help is greatly appreciated.