LIGGGHTS® - User Forum

Hello
So far, i am able to generate fibers in random orientation using LIGGGHTS-flexible fibers.
However I wish to generate fibers with a preferred orientation, i.e. fiber crientation should follow a probability distribution of the form: f(theta)= 1/pi -A*cos(2theta). Whare A is a user defined parameter (=0 for random distribution).
Is there a way to implement above in liggghts

Thanks
Shubham

Hello
I am currently using LIGGGHTS-flexible fiber version
For my research needs, I have to make changes in the granular bond model (may be bond_gran2) such that it also incorporates elasto-plastic effects.
Unfortunately, I am not very fluent in C/C++ , however, I can code in python environment.
Is there a way that I can write my custom code code in python and run it with LIGGGHTS?

Hi,

I am performing a biaxial compression simulation where I have a granular array surrounded by 4 extremely large granules to mimic a wall. In this simulation, I start off by fixing the left and bottom "walls" (big granules) and compress the array by adding a force (fix addforce) to move the top and right wall to compress the system. The force I use is to get a desired pressure in the confined state. Up to here all is good. I get a stress state which has the desired pressure. I add viscosity to dampen out the kinetic energy.

Hi,
I hope you are doing great.
Let's assume I have a dump called mydump, that prints the system state every 40 steps.
Later my system evolves and stops if a given condition happens (I use an if inside the run command). Many times this stop happens at some intermediate step, not multiple of 40, so the last system state is not dumped with mydump.
Can I call the dump command explicitly inside the if? right now I am just copying the full dump inside the if and using a write_dump, but this duplicates a lot of instructions than are difficult to keep in sync .

Hello
I am relatively new to LIGGGHTS-Flexible fiber version. I was going through the tutorials about using the restart files.
I some tutorial folders I found: main LIGGGHTS file, read_restart and write_restart files.
Can you please let me know (or direct me to a place where I can learn) about the meaning and how to use these different kinds of restart files.

Thank you very much

Shubham

Hi all,

1) Could you please explain the meaning of output of the following commands:
compute cpgl all pair/gran/local pos vel force (https://www.cfdem.com/media/DEM/docu/compute_pair_gran_local.html)
and dump dmp3 all local/gran/vtk 200 post/forcechainvtk*.vtk cpgl (https://www.cfdem.com/media/DEM/docu/dump_local_gran_vtk.html)?

Hello,
I am new to the field of simulation with LIGGGHTS. I have already done some tutorials and could already successfully import STL files here. I have a problem when importing a very large and complex geometry of a casting (many curves and different diameters).

Hello
I have a question regarding "Flexible fiber version'
I want to carry out an axial vibration test on a flexible fiber. Based on the chosen inter-particle distance (lattice spacing), we can discretize the fiber eithe closely packed or loosely packed. Please refer to the picture attached for quick reference.
Keeping one end fixed, if we axially pull the other end and release, vibrations are expected. My question is as follows:

Dear All,

the link which points to the syntax highlighting file is wrong. Can anybody send a usable link to the syntax file?

Thanks in advance, Feri

I'm running the same calculation (particles dropped in a box) on the same PC (4 core i7) using 4 threads in openmpi. Results are as expected the same, but calculation time varies drastically (up to 30%).
Commands are supplied from the same input file.
I'm using LIGGGHTS-PUBLIC 3.8.0

Anyone can explain why that could be?