LIGGGHTS® - User Forum

Hello,

I want to calculate the dissipation energy of particle collision in ball mill over time. I am not able find any command.

"The damping energy is the dissipated energy due to in-elastic contacts between particles and particle/balls/walls and is physically more related to particle breakage"

The specific damping energy at contact i is given by
Wm=
t
∫ F_dn * dε_n/m_i
0
, where F_dn is the normal damping force, dε_n the normal displacement over a whole contact period t and m_i is the mass of the particles.

Thank you.

Hey everyone,

I'm a beginner to LIGGGHTS and C++. I'm currently looking to modify LIGGGHTS to compute and store frictional dissipation at the contacts.

This was supposed to be an easy simulation but I am stuck here.
1) I am inserting particles in cylinder for few seconds
2) After insertion I want to settle it and make a packing in cylinder. My main aim is to fill cylinder more than 80% and make packing tighter.

When I run my script, simulation goes well. But while visualizing it, I see that particles are not piling up in cylinder instead, it penitrate my cylinder buttom and goes out.

I did used f f f boundary condition but I am still not able to fix it.

For sure, my mesh file does have solid buttom.

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: