LIGGGHTS® - User Forum

Hello, recently i used Liggghts Version 2.1.1 to do some simulations, howver I found two problems.
First, I found the simulation using Version 2.1.1 was very, very slow, I guess it was probaly about 6 times slower than the simualtion suing Version 1.5.1.
I don't know if anyone has similar problem.

Second, i met "insert region" problem when there were four materials in the simulation, it seems Liggghts didn't recoginze my definition of insert region
however, there was no such problem for the simulation with three materials. I attached my input file, maybe someone can help me with it.

error message

=======================================================================
LIGGGHTS (Version LIGGGHTS-PUBLIC 2.0.7, compiled 2012-08-25-16:06:53 by spe based on LAMMPS 20 Apr 2012)
Created orthogonal box = (-0.85 -0.08 -0.08) to (0.01 0.08 0.14)
1 by 1 by 1 MPI processor grid

Reading STL file 'barrel.stl'
Solid body detected in STL file
End of solid body detected in STL file.

Reading STL file 'screw.stl'
Solid body detected in STL file
End of solid body detected in STL file.

Hi All,

I want to learn how to set up the model of A rotary drum shown in the LIGGGHTS Feature, moving mesh. Is this model in the liggghts examples? or How can I find it?

Thanks,

Kun

Hi,

Hello,

I have met a problem by using restart. i have three related files. First one is for generating particles using "insert/pack", the second one is for making all paritlces settled in a box, the thrid one is for moving mesh box using "fix move/mesh" as follows:

"fix shear1 all move/mesh mesh top linear 0.005 0 0"

however I got following error message:

"ERROR: Illegal fix move/mesh command, illegal mesh ID provided (fix_move_mesh.cpp:63)"

acutally, i defined the mesh "box" in all three files using "fix mesh/surface/stress".

I just had a quick question. I hope it's okay. I am trying to do a comparison of the various forces present within my granular simulations and want to plot these in an excel spreadsheet.

I am using the gran/hertz/history pair_style but I am having problems seeing how the cohesionEnergyDensity is used. I cannot find mention of it in the manual so if anyone could point me in the right direction, or better yet let me know the equation that it appears in that would be really helpful for me!

Thanks!

Paul

Hi,

There were these two posts a while back:

node/100
node/193

but no updates since. I think that there is plenty of interest in the geomechanics community for stress control and membrane walls and I am wondering if these are still in the development pipeline.

Thanks,
Joe

Hi,

I'd like to set up a simulation with some clumped particles. In Version 1.5.3 my script startet with:

atom_style hybrid granular molecular

But if I want to start a simulation in Version 2.1 with:

atom_style hybrid granular molecular
or
atom_style hybrid sphere molecular

In both cases there is the message ERROR: Invalid atom style (atom.cpp:343).
Why this happens? Should i compile with some extra packages?

Best regards, Niels

I'm trying to run a simulation that uses two different atom types for the particles and for the walls. My code was based on a code that took its material properties from the meshGran tutorial in LIGGGHTS - ie, small young's modulus, only one atom type. I could get that code to run to completion (this simulation would fill up my hopper with particles and then empty them out in 150000 time steps, roughly 5 minutes).

Hello,

I am working on a rotating blade moving into a granular medium and would like to compute the force/torque exerted by the particles on the mesh. I use Liggghts version 2.1.1 and the fix "mesh/surface/stress".

My problem is that the output is invariably zero (see the helix.txt output file).
Can somebody help me finding the origin of the problem ?

The interesting part of my code is:


fix cad1 all mesh/surface file blade.stl type 1 scale 10 move 0. 0. 0.3
(insert particles and run some timesteps)