LIGGGHTS® - User Forum

Hallo,

as i am beginner to the LIGGGHTS. Therefore, I have a basic question regarding simulation time.

I am trying to compute the contact force acting the container wall. The container is under harmonic motion (Wiggle) and is partially filled with steel spherical particles.

If i set the following variable for time step:

hello,

I have a body (mesh) in my system, that I would like to let it have a specific (linear) movement but according to an equation that represents the acceleration and deceleration of it.

The equation is represented by 3 parts, each standing for a time phase, and they are in terms of a variable z.

I want to write a loop, that considers the increase of z by a certain increment that I define and includes three parts representing each equation within a certain time phase.

May you please suggest a way to define such a loop.

Thank you for your support.

Hello everyone,

label loop_growth

run ${grow_every2}

variable curr_dia2 equal ${start_dia2}+step*${grow_rate_dia2}
variable new_z1 equal ${z1}+(${curr_dia2}-${start_dia2})/2
change_box all z final 0.0 ${new_z1} units box

if "${curr_dia2} > ${end_dia2}" then
"jump SELF done_growth"
else
"jump SELF loop_growth"
endif

label done_growth

Dear Colleagues,

I am trying to implement a shear test simulation and i am using a hex lattice to create upper wall and bottom wall.
The issue i have, when i start my simulation there is no contact between the particles and between the particles and the walls.
i tried several things to fix the issue but i couldn't.
any help will be really appreciated.

I attached the input file for check.

Best
Saeed

Hello, I am trying to simulate a mix of grains. For which I have written all desired variables in the in.script. However, while uploading the files, I get:
ERROR: Invalid syntax in variable formula (/build/liggghts-T4i5up/liggghts-3.8.0+repack1/src/variable.cpp:1645)
If anyone can tell me what's wrong in my script, I'll be thankful.

Hello,
I am trying to simulate granular flow around a horizontal tubes of a particle heat exchanger and validate the results with the experimental results of Bartsch et at(https://www.sciencedirect.com/science/article/pii/S0038092X19300982) but I am getting zigzag velocity profile at any z plane but in their results they are getting a nice velocity profile. If anyone can help me regarding this problem then it will be thankful to you.

Hi,

I am attempting to compile LIGGGHTS on Ubuntu 20.04.

My Makefile.user has the following flags and paths set:

Created orthogonal box = (-0.4 -0.05 -0.05) to (0.35 0.1 0.4)
2 by 1 by 2 MPI processor grid
ERROR on proc 0: Cannot open mesh file mesh/Box.stl (../input_mesh_tri.cpp:115)
--------------------------------------------------------------------------
MPI_ABORT was invoked on rank 0 in communicator MPI_COMM_WORLD
with errorcode 1.

Hello,
I am the beginner in LIGGGHTS and I am trying to get the particle distribution/ volume fraction of any local region of the DEM simulation domain. I came to know in the forum that it can be done by Voro++ but I don't have any idea how to use it. Can anybody help me in this regard? It will be really great help if anyone can do.

error:

Primary job terminated normally, but 1 process returned
a non-zero exit code. Per user-direction, the job has been aborted.
mpirun detected that one or more processes exited with non-zero status, thus causing
the job to be terminated. The first process to do so was:

Process name: [[5963,1],4]
Exit code: 1

In my understanding, liggghts use domain-based decomposition for parallelizing. In my case, some of the same set of elements are processed by different processors. Please suggest some way to avoid that.