LIGGGHTS® - User Forum

Dear friends,
Could some body please let me know how can I apply rotation and translation (at the same time) to a moving mesh imported from a stl file. Any response will be truly appreciated.
Regards,
Carlos

Hi all,

I'm trying to set up a sim with a region of fixed temperature particles at the top and bottom, and particles that have variable temperature in between. The docs suggest I do not include adiabatic particles in the heat/gran fix. So I've set up a lattice of (4200) particles and defined regions as:

region upper block INF INF INF INF ${upper_limit} INF units box
region lower block INF INF INF INF INF ${lower_limit} units box
region middle union 2 upper lower side out

group thermal_group region middle
3000 atoms in group thermal_group

Hi everybody,
I would like to start the shear test using LIGGGHTS.
Could you help me in doing it.
I was using velocity command for the control of temperature. So far no success. I came to know about the shear test from the following message.
Many thanks in advance.
Samantaray

Tue, 11/30/2010 - 17:18 — tshan

Dear all,

I have already done some triaxial tests and simple shear tests, but I want to know the contact normal among the particles and then realise them in paraview to further generate the force-chain.

Hi Chris,
Could you give hints about the calculation of neighbors in LIGGGHTS?
I am using the following commands in the programme.
lattice fcc 0.0013
neighbor 0.00125 bin

It is creating
Total # of neighbors = 48418
Ave neighs/atom = 24.209
Neighbor list builds = 27

Hi

i need create 2 atoms with different youngsModulus parametr.

i try this:

fix m1 all property/global youngsModulus peratomtype 5.e7 5.e6

create_atoms 1 single 0.0 0.0 10.0
set atom 1 density 2000 diameter 2.0

create_atoms 2 single 5 0.0 10.0
set atom 2 density 2000 diameter 2.0

So i get that ERROR: Invalid atom type in create_atoms command
What's wrong?

Thanks
jikra

Hi, all

I just got an error with the 'fix' when running the LIGGGHTS examples:

fix m1 all property/global youngsModulus peratomtype 5.e6
ERROR: Invalid fix style

It seems the property/global is a LIGGGHTS style for the 'fix'.
The LAMMPS examples were done well, without any error, perhaps the LIGGGHTS was not invoked properly??

Any help is appreciated.

Hi everyone,

I'm trying to set up a simulation with 3 spheres clumped together, exactly as seen in LIGGGHTS Features > Non-spherical particles > Example - pouring a continuous stream of non-spherical particles, where can be seen particles made of 3 spheres glued together.

I'm exploring some possibilities to do a modification of this study http://www.nt.ntnu.no/users/skoge/prost/proceedings/ecce6_sep07/upload/1... by simulating a packed bed with non-spherical particle as my PhD study. My idea is starting with 3 spheres glued and then move on with different particle geometries.

Hi all,

I have so far been running LIGGGHTS with more-or-less "large" particles (mm/cm), but now want to move towards the size that interests me, around ~1 µm or so. However, if I try to use fix particletemplate/sphere and fix particledistribution/discrete to generate small particles I get an error which seems to arise from a hard-coded limit:

if(volume_expect < 1e-12) error->all("Fix template/sphere: Volume expectancy too small");

in fix_template_sphere.cpp.

Hi. I want to use mesh/tet and insert/pack features.
I use in.insert_pack example file as basic for my simulation.
But I get an error when I use own insertion region geometry file instead of test.vtk:

LIGGGHTS 1.4.1 based on lammps-10Mar10
Created orthogonal box = (-1 -1 -1) to (1 6 2)
1 by 4 by 1 processor grid
Fix particledistribution/discrete (id pdd1): distribution based on mass%:
pts1: d=5.000000e-02 (max. bounding sphere) mass%=30.000000%
pts2: d=3.000000e-02 (max. bounding sphere) mass%=70.000000%

Hi all,

I had a look at the gran/hook/history/simple pair_style today. I thought that this pair_style should make you able to directly set the values for kn, kt, gamman and gammat depending on the contact-partners. So I was wondering why the values for the damping coefficients (gamman and gammat) are multiplied by meff. The same modification is done for wall-contacts.

I think that should be changed otherwise you have to take the multiplications into account when you set the values in the input-script.

Regards,

Yansan