LIGGGHTS® - User Forum

Hi, All

I'm a new user of LIGGGHTS, and am now here seeking for some help.
I am currently coding a simulation for compression triaxial tests.
I understand that using 'fix particledistribution/discrete', we are able to insert particles according to specific fraction of diameters.
However, I wonder if there is any approaches to present the whole particle size distribution curve for various particle diameters in a simulation?

Thank you.

Best Regards,
Renge

Hi all,
I am new in LIGGGHTS. Would you please guide me?

1- Can I install LIGGGHTS on windows? how?

2- Is it free?

3- Should I write my own code? or there are some pre-set code?

4- I want to study and see the movement of non spherical particles (needle shape) in pipeline containing fluid would you please guide me? can LIGGGHTS be helpful?

Regards,

Taher

Hi all,

I am running a simple case with 2 particles bouncing in a closed box.
At certain time, I can see there is a gap between particles and the wall but still it detects as a contact which seems to be wrong. (visualization in paraview )

I am writing the history of contact-area in the dump files called "localwall.contact" . You might be able to view this file when you run it.
In my case, it happens at 9579, 28851,48123 time-steps and so on i.e it happens for every 19272 time-steps after the first wrong detection.

Dear users,
I'm using LIGGGHTS to perform SPH simulations, and I would like to start the simulation with:

boundary f f p #periodic boundary in z direction

run it for couple of steps, and after that change the boundaries to:

boundary f f f # all fixed boundaries

and run it.

I tried with:

.
.
.
run 1e5
change_box all boundary f f f remap units box
run 1e5

but it does not work. In the output file I get a message:

.
.
.
Changing box ...
Setting up run ...

Hi, all

Are there any commands in LIGGGHTS that is similar to the "local damping" in PFC?
I want to use this command because the simulation is a quasi-static problem. By adopting local damping, the simulation could be greatly sped up without losing accuracy.

Many thanks,

Liu

Hello everybody,

I'm working on a very simple test-case (see input file below). Two particles, one on the top of the other with a normal spring between them (pair_style gran model/hooke/stifness) are compacted in one direction (fix comp all deform 1 z trate -1).

In the dump file, I get the expected positions and forces (components z and fz), but the velocity in the z direction (vz) is 0 for both particles at all time steps.

What am I doing wrong?

Thanks for your help.

Robin

Hi all,

I am trying to restart the simulation by changing the data file by using "read_restart tmp.restart.120000" command (120000 is the last iteration where I stopped my simulation)

But I was getting this error:

ERROR: Cannot read_restart after simulation box is defined (../read_restart.cpp:75)

Can anyone please help me in fixing this?

Thank you.

Dear users and developers,

I am simulating a simple container with an inlet and outlet (both have much smaller diameters than container diameter). I insert
particles at the upper side (in the inlet) and they fall under gravity through the container and out to the outlet.
The system boundaries are fixed and particle tracking is set to "lost" so to save computational cost (I am not interested in particles exiting the outlet, only while they are inside is what matters).

I wonder what is the difference between these two types. The sph examples available with LIGGGHTS use the 'sph' type, but the examples in SPH LAMMPS userguide use the 'meso' type.