LIGGGHTS® - User Forum

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.

Dear LIGGGHTS users,

I'm wondering how can I fix the walls in the simulation to prevent their movement (not from the beginning, at the certain point of my analysis).

Thank you!
Bee