LIGGGHTS® - User Forum

Hi all,

I am new to LIGGGHTS. After modifying the .stl file, I am getting the following error just after the code executes the fix command:

"fix cad1 all mesh/surface file screw.stl type 2 scale 1.0 curvature 1e-05
ERROR: Input line quote not followed by whitespace"

My script was working fine just with the old STL. Also, there is no problem in the new STL, as I used that in my earlier scripts.

Any ideas on what might be the reason behind this??

Thanks & Regards,
Aashish

I am generating the particles in box and let them settle down. Once the particle settle down, I unfix the gravity earlier defined and using fix/freeze comand to stick the particle to the base so that I can have bumpy base. Now I tilt the gravity to 25 degree but freeze layer is also flowing Can any one please tell what's wrong with the my code?
#Simple chute wear test

atom_style granular
atom_modify map array
boundary p p f
newton off

communicate single vel yes

units si

region reg block 0.0 0.1 0.0 0.1 0.0 0.15 units box

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